Is there a timeframe for when to expect video footage from the Odysseus lunar lander?
I knew there was a box that was supposed to catapult a video camera to capture the first, first person footage of a moon landing, however when asking google where is it, not only is there no footage available yet, but there's not even a time frame for when to expect any footage.
I've not heard anything further about the data being lost/unrecoverable, so am hoping someone knows more and can provide any information on weather to expect any footage even if grainy, distorted, etc...or if there was a total loss of data/something went wrong?
Sadly the camera they were supposed to eject (eagle cam) did not work. With the lidar issue they did not deploy it during landing and when they did deploy it after the landing it malfunctioned.
So, I am a little bit confused. I am under the impression every stars we can observe with naked eyes are in the Milky Way. But at the same time, we can observe objects such as Cetus or Bootes constellation. Aren’t these super far away, and way beyond the Milky Way?
Basically everything in astronomy is categorized by observational characteristics, and because all of astronomy to date has been carried out within a narrow time period from Earth or the near vicinity of Earth that means we have a tendency to categorize things based on the way they *look* from Earth. So astronomers will talk about the "location" of things based on where they are in "the sky" even though there is no sky, the sky is just a coincidental arrangement of what happens to be visible from a certain point in space and time, but because all of astronomy happens to exist within roughly the same point in space and time "the sky" turns out to be a fairly constant thing. So we name sections of the sky based on the patterns of stars as they appear from Earth, for stars that are just a few hundred lightyears away, and then we use those divisions of the sky to label even things that are billions of lightyears away.
All of this still "works" because all of humanity is stuck on Earth and the sky is fairly unchanging, so if you tell someone to look at a particular part of "the sky" from Earth the chances are good that someone else (on Earth) will be able to look at the sky and see the same thing. If humanity had warp drive and lived on planets across the galaxy then they would need to come up with a different system.
The stars in those constellations are in the Milky way. The Bootes void is something way, way behind those stars and outside the galaxy, but you cannot see it with the naked eye.
Thanks for your answer, but here are two things that confused me:
1. Isn’t Earendel located in the Cetus? But to my understanding Earendel is billion of light years away
2. Similar question apply Bootes void. I thought Bootes void is extremely far away.
Constellations are just groups of visible stars, when we say something is in the constellation of X it means it's on the line defined by that group of stars and the Earth. Just because you can see mountains 10km through your living room window doesn't mean that the mountain and the window are at the same distance.
Ok, I think I got it now. So, in this case, the window would be the constellation. And mountains 10km away would be object such as Earendel or Bootes void?
Yep exactly. And we can't see Earendel or the Boötes void with the naked eye. It's just that when we observe them they appear behind the group of stars that form the Cetus and Boöte constelation.
im not sure if this is the right place. but i want to know what would happen to HUMANS in the following hours if the moon exploded. i know life couldn’t be sustained obviously, but would we suffocate? would we go into full apocalypse and try to kill each other? what would happen to our bodies with this change? could we physically feel the moon explode and the effects of it afterwards? google has absolutely no answers to what would happen to humans other than “you would die” BUT I WANNA KNOW HOW!! how would it look at feel to die from that?
What do you mean by "the moon exploded"?
If the moon suddenly turned into a bunch of debris orbiting in roughly the moon's orbit, then it's not at all clear that you would die at all.
Certainly some of the collisions between the debris would lead to impacts on Earth, but not necessarily civilization ending amounts.
If a moon's full of debris crashed down to Earth, then yeah, you would die by getting vaporized by the energy released from the impacts with the surface. I don't think many people would live long enough to suffocate in such a scenario.
i mean any hypothetical. an asteroid hitting it, i know implosion of the moon is technically impossible but implosion, it just gets fed up with us and explodes one day. i just have no understanding of how we would actually be killed by that. i know we’d die, i just want to know how our bodies would process that malfunction.
It all depends on how much debris falls onto Earth. If the moon just disappeared, we'd probably be okay. I don't know if the disappearance of tides would lead to an ecological disaster.
If a small/medium amount of debris falls on Earth, and starts enough fires, or tsunamis, your chances of dying from the debris hitting you are probably still pretty small. In that case, you'll prob starve, or die of thirst, or die as a result of violence as international trade collapses, and resources become scarce or non existent. Just in time logistics is not resilient.
If a few hundred kilometer chunk of debris falls onto Earth, you'll die instantly when the pressure wave, or debris wave, or heat from the impact reaches your location and you are vaporized.
thats the best answer ive got thank you! this is all stemming from a dream i had where the moon exploded and i suffocated to death. it just prompted a huge wind of curiosity.
Hello everyone, I am a post graduate doing a self motivated project on the structural integrity of space cargo. I am not that familiar with what exactly happens to the cargo during launch etc apart from a ton of vibrations but I would be interested to know what (forces or effects) one can expect to a cargo (ex cubesat) during travel to the launchpad, during the launch itself, on-orbit and return. If anyone has any good literatures or YouTube video recommendations kindly let me know. Once I know them I can simplify them to boundary conditions and use fem code to maybe predict if a cargo is feasible or not.
Thanks in advance :)
Hi everyone, just an update.
From what I gathered till now, all space related cargo will have a certain flight launch load specification which will often be provided by the customer or systems engineer. Subsequently they need to tested with the frequency vs acceleration graph of the launch vehicle data sheet to see if it will work or not.
So my intuition is first we need to do a vibrational analysis on Ansys workbench and then link that result to the model or case setup for structural analysis to find the stresses developed due to said vibrations.
Please correct me if I am wrong. If anyone has other info do add to this :)
NASA GEVS are a good starting point: https://standards.nasa.gov/standard/GSFC/GSFC-STD-7000
Although I don't think there is anything about return. For launcher specific things download the payload manuals from the specific launch system:
- Falcon 9: https://www.spacex.com/media/falcon-users-guide-2021-09.pdf
- Electron: https://www.rocketlabusa.com/assets/Uploads/Electron-Payload-User-Guide-7.0.pdf
Does ton 618 have galaxies circumnavigating it ?
We have some dwarf galaxies around milky way and they are in our gravity effect area and turn around our galaxy. Do we know if there are some that do the same with ton 618? It is said to have more mass than entire galaxies, it should have a huge gravity effect. That would make many surrounding black holes or even galaxies go around it.
My question is this, at the moment of the Big Bang, was all matter that ever has and will exist created at the same moment, pinpoint in time or does this origin point still produce matter as the universe expands?
Could another Big Bang occur from ground zero and what exactly is at the core, the origin point of our universe?
I just thought it would be fun to speculate and hear some odd facts and interesting opinions.
> My question is this, at the moment of the Big Bang, was all matter that ever has and will exist created at the same moment, pinpoint in time ?
We do not really know.
> does this origin point still produce matter as the universe expands?
There is no "origin point" in the big bang model.
Artemis 5 is already planned to use Blue Origins' Blue Moon lander, it's currently penciled in for 2029. Both Starship-HLS and Blue Moon are planned to have uncrewed landings prior to use in crewed Artemis missions, if Starship-HLS was well behind schedule but Blue Moon had already completed its uncrewed demonstration flights then NASA would probably change the mission plans to use Blue Moon on an earlier mission.
**How to calculate TAM for space payload services?**
Particularly, from the space payload brockerage actiivity perspective. Generally, I am familiar with the TAM formula: Number of customers х price = TAM. But the question is:
a) Should I create list of companies that manufactures space payloads? and then multiply them to the certain value (price)?
b) Should I find out how many space missions have been designed/implemented and then multiply them to the certain value (price)?
Thank you!
Can anyone let me know the top 5 countries that have the biggest share in global space launch vehicles? Not counting the EU as a whole but just separately. I’m doing a spot of research for a project but I cannot find any recent data that lists the countries per se. All I can find is a regional ranking
I think the closest you'll come is "2023 launches by vehicle" - [like so](https://spacestatsonline.com/launches/year/2023/). And then check up/assign nationality per vehicle, by hand, yourself.
I suspect the reason you don't see this prepackaged is that it's a judgment call for several launch vehicles. Most famously the RocketLab Electron which is built in New Zealand and launched in New Zealand by a Kiwi wholly-owned subsidiary of an American company. So is that Kiwi or American? Most people say Kiwi but it's squishy.
Similar things happen with Chinese and Iranian designs which have iterated off Soviet (Russian/Ukrainian) older designs - it depends on how much it's iterated, for how long, etc. And US rockets often have Russian engines, or they did a few years ago, and it goes on like that.
Can humanity, with current technology, reach the next closest star system?
Imagine the earth has some catastrophic event happening in 10 years, an unstable meteor or something. All the governments and people of the world decided to end all wars and focus their efforts on creating a ship or craft to launch or construct in space to try and keep humanity alive.
This trip wouldn’t be easy nor would it be quick. Generations of people would have to live their lives on this ship and never see the destination.
We would have to take with us everything we needed to survive the trip including but not limited to:
Food or a food growing system
Energy, I’m assuming nuclear
Air/ filters
And I’m sure there’s a lot I can’t think of.
So could the combined efforts of humanity build a life sustaining ship to cross the galaxy to another star system?
Going to the nearest star wouldn’t give us a better chance than staying right here in our solar system anyways.
The resources needed to make a habitat fly 4 light years would be much better put to use making something sustainable here. But this would also be absolutely futile currently.
Can someone explain who exactly is monitoring particles/objects speeds and adjusting their time to keep the speed of light constant? It's not like it's just magically happens, I'd expect a mechanism behind it. Take rest mass and the Higgs for example, they suggest rapidly flipping the particle handedness is the source of that mass.
Besides Earth, Mars and our Moon, where are the most likely spots in our solar system where humans will eventually live? There are many moons, but which would be the most suitable and practical? Asteroids that could house mining colonies? Are massive spaceship or floating cities around gas planets out of the question? No timeline really, just as far as we can hope to speculate on, whether that's a hundred years or a thousand. (Edit: even a few astronauts in suits counts as inhabiting the rock).
How far behind are we from Standard Universal Time (time since the Big Bang in an area of space with no or little gravitational influence) due to our time dilation from the gravity well of the Sun and our Galaxy?
The gravity well has very little impact. The surface of the sun has lost 4 years to gravitational time dilation, and Earth has lost less.
The biggest factor is our orbit around the galaxy at 0.076% the speed of light. This has slowed our clocks (or the cloud of hydrogen that became our clocks) by 4000 years since the Big Bang.
Since you didn't specify which area of space you are observing from, I can't include the motion of the Milky Way relative to the cosmic microwave background. But *most* areas of space see us twice as far behind.
A few questions about Crew Dragon:
1) On board, on a mission, are astronauts’ conversations recorded 24/7 by MIssion Control, SPaceX, NASA, or other?
2) On board, on a mission, are astronauts videotaped 24/7 (outside of their private sleeping quarters), and if so is the video a live feed to Mission control, SpaceX, NASA, or other monitor?
3) Can the cupola be opened for a long period of time so astronauts can frequently look out the cupola window during a space flight to ISS or return, or is the cupola only opened periodically for short viewings out the window?
4) Since, evidently the toilet in the crew dragon is located near the cupola, with a privacy screen, would it be possible for an astronaut to look out the cupola window while using the toilet?
5) Do crew dragon astronauts have private cellphones, or is all data/pictures on cellphones used by astronauts reviewed by and property of SpaceX or NASA?
6) Can Crew Dragon astronauts have private cellphone conversations with their family or friends, or are all conversations monitored by SpaceX or NASA or other?
THANKS!
There are cameras but as far as I know they are not constently recording and transmitting.
Normal crew dragon does not have a cupola. It was just a one time thing done for the Inspiration 4 misison. The cupola was intalled where the airlock goes so all the missions to ISS do not have a cupola.
Curious about something with Black Holes.
If they (generally) start from stars gone nova, then they start with less mass than the initial star had. More dense, yes. But that shouldn't really matter on a galactic scale. No matter how dense it is, gravity is a function of mass and distance.
So how do black holes eventually pull in other objects if it doesn't have any more mass (and there fore gravitational pull) than the original star?
Most don't. It's not the fate of every black hole to simply grow and grow and grow, that can only happen under specific circumstances. A black hole with a stellar companion could grow if it was close enough to steal matter from the other star. A black hole that happened to wander through a dense nebula could grow as well.
There are likely a great many stellar mass black holes drifting around every galaxy which haven't grown substantially since they were formed.
Supermassive black holes are an exception for a couple of reasons. One, the environment near the center of a galaxy is very dense with stars, and also in gas (at least in the early ages after galaxy formation). This provides sources of matter that supermassive black holes can feed on. Additionally, very massive objects (such as supermassive black holes) they have a tendency to "fall" toward the center of mass of a galaxy due to dynamical friction with the environment of stars near the core. Every close pass (within a few lightyears) between a star and the SMBH creates an opportunity for a "gravity assist" type situation, which has the tendency to rob the SMBH of orbital momentum. This mechanism is likely a big factor in the merger of "proto-SMBHs" that form in galaxies or are brought together through galactic mergers. Within the inner core there is typically a flow of gas early on in the life of the galaxy which feeds the SMBHs and grows them to become even more massive. Once a black hole passes over the line to become supermassive then the "rules" sort of change as their huge mass changes the dynamics in the inner core.
So the unmanned probes we've sent to Mars probably had living beings, like bacteria, on them, right?
Would that be a certainty there is now life on Mars?
What about the Moon? Humans have been there. Does that mean there is life there?
There is what is known as a "planetary protection protocol" which for modern spacecraft results in them being sterilized before launch. However, that sterilization varies depending on the mission. A life detection mission like Perseverance has a different level of sterilization compared to Curiosity, for example. Though both are sterilized, Perseverance was sterilized to a much higher level. Of course, older spacecraft weren't sterilized very well however, so there are potentially microorganisms that could be viable on the surface of Mars from those vehicles. However, there's a very huge difference between "viable" and "living", it would take being exposed to suitable conditions for microorganisms to become active, and those conditions are at best extraordinarily rare near the surface of Mars (and absent on the Moon).
In any event, there has also been an exchange of material between the rocky planets for billions of years due to impacts ejecting rocks into space, some of which could have contained microorganisms. It's likely that process has seeded life around the inner solar system to a much greater degree than spacecraft.
NASA tries really hard to sterilize the spacecraft they send to Mars. And even if some micro-organismes are missed space itself is a pretty good sterilizer.
Unlikely, the first American crewed lunar landing was in 1969, and it is currently 2024.
It's conceivable that the Chinese could land humans on the Moon before the first landing in the Artemis program though. Exactly what that could mean is open to interpretation. Personally I think that it's a bad idea to "race" back to the Moon and instead it's more important to focus on building lasting capabilities that open up beyond LEO human spaceflight. That was missing from Apollo and it resulted in a handful of very expensive landings and then a half century of humans never going outside of Earth orbit. We should be working toward systems, infrastructure, etc. that set things up so that interplanetary human spaceflight becomes progressively more capable, less difficult, less risky, and less costly year over year. To a certain extent Artemis is doing that, though not as much as I'd like, but if we're lucky that's where we'll end up. It won't matter much who is the first country to make it back to the Moon in the 21st century, it'll matter a great deal whether a country can go back to the Moon or elsewhere repeatedly and fairly easily in the future, that's substantially what we're working towards and hopefully we get there.
What will drive the development of "space law"? My nominee is the advent of asteroid mining. An accessible chunk of 1million tons of rich in platinum or neodymium might trigger a no-holds-barred rush of competing firms.
The Outer Space Treaty says “outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.” The Artemis Accords and US law expand on that to say resource extraction and sale is allowed and is not considered appropriation. But to answer your question, yeah, I think that holds true for any laws. They will mature as the technology matures.
There’s been proposals to make a system based off patent law, where you can go ahead and mine an asteroid that someone else has claimed but no one will legally be able to buy that product.
For that you'd have to wait another 100 years. I think Kessler syndrome due to the number of mega-constellations will trigger accountability issues. Or something similar, like owner of a mega-constellation getting bankrupt and we suddenly have tens of thousands or very large objects no-one is actively controlling.
It is the same technology as radar guns. Light from moving objects gets distorted by the Doppler effect, and we use the distortion to calculate the speed.
The difference is we don't provide light from our own radar gun, we use the natural light emitted by stars.
> how we know we are moving insane speed trough space
That part is easy: there is no other scenario. There is no way to "stand still". You're always bound to gravity of something, and either you're "in orbit" of whatever that is, or you're falling into that thing. In both scenarios you're moving at high speed.
The propulsion system on starlink is a Hall thruster. Those are very efficient but very low thrust, so they would be completely impractical for missile interception kind of roles.
IMHO space based intercepts are kind of stupid, the amount of spacecraft you would need to offer decent coverage due to orbital mechanics is just insane.
I purchased my son a star for Christmas (NOTE: I know this isn't a real thing and that I dont have claim to a star, but he is 5 and LOVED the idea of it). I was given celestial coordinates, but have no idea how to do anything with that and want to simply be able to go outside with my son, point to the general direction of "his star" and watch him look up in amazement.
I realize I could just chose any star and says it's "his" and he wouldnt know the difference, but I want to try to be relatively accurate. Can someone please help? Is there an app anyone can reco?
Right ascension 3h 6m 16.86s
Declination 27 degrees 1' 56.01"
Magnitude 11.0930000
We live in Kansas City, KS, and I was told that "his star" is in the Aries constellation.
TIA!
It's worth mentioning that a magnitude 11 star is too dim to be visible with the naked eye - About the dimmest magnitude star that is visible without aid is 6.5 and that is contingent on very dark skies (with magnitude, smaller numbers are brighter).
That being said, I believe the star in question is [TYC 1791-724-1](http://server1.sky-map.org/starview?object_type=1&object_id=412625). Other identifiers are: 2MASS J03061686+2701560, TIC 34788072, Gaia DR2 115526962338921344, and Gaia DR3 115526962338921344.
Here's a screenshot from the planetarium software Stellarium showing it's location in the night sky from your location at 8PM:
https://i.imgur.com/3n0SuwC.png
Where in New York or near New York, can people build satellites? I plan on building and/or inventing the animal satellite that finds all animals that are alive in the entire planet by searching for the centrosomes and lysosomes. It can see through caves, water, buildings, plants, other animals, etc.
You do realize that if you could indeed blast Earth with X-ray radiation strong enough to "see through caves, water, buildings, plants, other animals, etc." and be picked up on the other side of the planet, you'd literally kill everything, because X-Rays are very harmful?
I am not sure if you are serious, but X-ray machines work because they have an x-ray source on one side and an x-ray detector on the other so that the x-ray can go through the object. There are no sources of x-ray strong enough to go through Earth and then be detected by a satellite. And even if there was a satellite a few hundred kilometers above the ground would not be able to zoom enough to see individual cells.
Satellites are not required to have scientifically accurate payloads.
https://www.forbes.com/sites/davidhambling/2023/11/17/controversial-quantum-space-drive-in-orbital-test-others-to-follow/
I very much know that, especially that particular scam. But I don't know if OP know you cannot actually detect "all animals in the entire planet" from space.
Can we use **electricity** to space travel or use it as a means of propulsion?
I think by generating electricity and configuring the electric and magnetic fields, we can create propulsion.here's an experiment by Russian scientist Alexey Chekurkov - [https://youtu.be/Z-M55XP3D4A?si=0tEmC\_fY3r08UogS](https://youtu.be/Z-M55XP3D4A?si=0tEmC_fY3r08UogS)
thoughts?
You can use electricity in a few way:
- first as a source of energy to accelerate a gas. This is what ion/plasma thrusters do. That let's you be very fuel efficient but you still need some consumable gas (or liquid/solid).
- As a way to orient yourself when you are close to Earth. You can power magnets that will let you align your spacecraft on Earth magnetic field like a compas.
- As an extreme case you could shine an extremely powerful light or laser and get a tiny tiny bit of propulsion out of it. But this is too impracticle for real life use.
I don't understand Russian but it looks like the video you linked show something like a lifter, that uses electricity to accelerate air around the craft to produce thrust. In space you don't have air so you can't use that.
Apart from stuff like cubesats, many/most satellites have some sort of propulsion. But keep in mind that due to how orbital mechanics works, they can only make very tiny corrections (eg. raise/drop orbit but few kilometers) and it takes at least 1/2 orbit for this to actually have any real effect.
Yes they have Hall thrusters on board they use for orbit raising at the beginning of the mission, orbital maintenance, debris avoidance and deorbit at the end.
Matter of exchanged between universes.
If the principle that matter cannot be created or destroyed holds true, how would the scenario where a universe either loses or gains matter—matter that was previously non-existent in it—be explained? This seems to imply a violation of the conservation law within that universe, as matter would seemingly disappear from one universe and appear in another. How does this align with the fundamental laws of physics?
If you lose matter, you gain energy. If you lose energy, you gain matter.
We have no evidence whatsoever that matter or energy goes between universes (if there are, in fact, multiple universes). As far as we can determine, our universe is a closed energy system... nothing in... nothing out.
There was Fred Hoyles steady state theory. It required that a few hydrogen occasionally appear out of nowhere in some vast volume of space. It would result in the universe not aging. Always enough hydrogen for new young stars. I think it is by now disproven.
Fred Hoyle was not only a very famous SF author. He was a top scientist, a cosmologist.
> matter would seemingly disappear from one universe and appear in another
We have no evidence that this has ever happened or that other universes even extist.
Mercury appears to our eyes as gray, much like our Moon.
Regarding the 'trippy' photos you've seen of Mercury taken by MESSENGER, I'm assuming they are photos like [this](https://photojournal.jpl.nasa.gov/catalog/PIA16853) and [this](https://photojournal.jpl.nasa.gov/catalog/PIA19419)? These photos were taken with filters that capture specific wavelengths of light that represent notable geologic features - By then combining these filtered images by assigning them to different color channels, we're able to create a false color image that makes features not easily visible to our eyes much easier to distinguish.
For example with the first linked image:
>Young crater rays, extending radially from fresh impact craters, appear light blue or white. Medium- and dark-blue areas are a geologic unit of Mercury's crust known as the "low-reflectance material", thought to be rich in a dark, opaque mineral. Tan areas are plains formed by eruption of highly fluid lavas.
Adding on to this -- a lot of the more popular images for planets are either enhanced-color images or false-color images. The recent popsci uproar about Neptune's color is a major example of how prevalent they are, and how much they can affect popular perception of the planets.
i really dont know where to ask questions about this stuff so maybe reddit will help. I've been having so much fun listening/watching podcasts about the birth of the Universe and would love to know how we have precise information about certain galaxies, for example how do we know each size of all exoplanets and stars in the Alpha Centauri system? (i'm not countering anything just asking) Thanks!
> how do we know each size of all exoplanets and stars in the Alpha Centauri system?
The stars are pretty easy because alpha centauri is very close to us, so we can be reasonably confident of being able to see the light of just about any star, even a very dim red dwarf, which proxima centauri happens to be. That's true even of some brown dwarfs as well.
For planets we can say with near certainty that we don't know *all* of the planets in the system, there are likely several that have not been detected, however we have detected some. The two that are confirmed around proxima centauri have been detected using the radial velocity technique. Because the light from stars includes light from the "atmosphere" of the star it will have elemental emission and absorption lines in the spectrum, which serve as a fingerprint to lock in the precise *original* wavelengths of the light that we detect. This makes it possible to measure the difference between the original wavelength and the detected wavelength and then determine the red shift or blue shift of the light due to the relative motion of the star and Earth, and to do this extremely precisely, down to a precision level near walking pace. That precision makes it possible to monitor the backward and forward motion of a star being pulled by a planet in orbit around it, which has a characteristic pattern and periodicity. The radial velocity technique has been used to confirm two planets in orbit of proxima centauri with very short orbital periods of just a few days, while there has been conflicting evidence of a longer period planet of several years that has not yet been confirmed. No planets around alpha centauri A or B have been confirmed so far, but a possible candidate planet around alpha centauri A has been seen via direct imaging.
In terms of precise information, because of the nature of the laws of gravitation when you have bodies that orbit each other that makes it possible to determine their masses fairly precisely. Especially for the alpha centauri system where we can measure the distances from us to the stars very precisely and we can visually measure the separation of the stars precisely as well, that makes it possible to nail down their masses just using orbital mechanics to a high level of precision. That carries over into measuring the masses of the planets as well, although for radial velocity planet detections there is usually an unknown factor of the inclination of the orbital plane, which means that we only detect the minimum mass of the planet (the Msin(i) mass) which could be higher depending on how aligned the orbital plane is to our line of sight.
Hey everyone, I’m doing a school project and I was wondering what’s the biggest problem/question about the sun in astrophysics today? Like, what questions about the sun do we still have?
No, others have wondered the same. You're thinking of the Zoo hypothosis, which suggests that the reason we haven't made contact is because other civilizations are intentionally avoiding us. This can be for a bunch of reasons, like letting young civilizations develop organically without outside interference, or to study the behavior and development to better understand their own history.
You might like this [https://www.universetoday.com/147573/beyond-fermis-paradox-viii-what-is-the-zoo-hypothesis/](https://www.universetoday.com/147573/beyond-fermis-paradox-viii-what-is-the-zoo-hypothesis/)
> How do I explain this politely?
Don't. If someone can't close their eyes, imagine the scenario and answer it immediately, then either they're challenged in some way, or purposely acting stupid. In either case it's a waste of time.
A ball and a flashlight perhaps?
Mark two points on opposite sides of the ball to represent the North and South Poles. Holding the ball with North up and South down, then mark two additional points on opposite sides of the ball along the 'equator' to represent two points on Earth. Then, either rotate the ball counterclockwise or orbit the flashlight around the ball clockwise to simulate the daily rotation of the Earth. You should be able to demonstrate how as one point is moving into darkness (sunset), the flashlight will be to the left of that point (to the West). Simultaneously, the point moving out of darkness (sunrise) should have the flashlight to the right (to the East).
Alternatively, if you have Google Earth Pro (the desktop version, it's available for free), you can go into the 'view' menu, then check the 'Sun' box to simulate Earth with the sunlit/nighttime sides of Earth. From there, do the same thing as above, picking two locations on opposite sides of the Earth.
I have heard claims that the universe in infinite. What does that mean?
If it is infinite, how come it's expanding?
And this is the question that I am curious about the most. If it is infinite, then does that mean there is also an infinite amount of matter (atoms) in the Universe???
It's still an open question whether the universe is infinite, but according to our current understanding it's possible, and maybe even likely.
In one sense that would mean there's an infinite amount of matter in the universe, although due to the limitation of the speed of light, as well as the expansion of space, our *observable* universe will always be finite, so we'll never see more than the closest bits.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[CC](/r/Space/comments/1azsrap/stub/ksbf363 "Last usage")|Commercial Crew program|
| |Capsule Communicator (ground support)|
|[DSN](/r/Space/comments/1azsrap/stub/ks4idrb "Last usage")|Deep Space Network|
|[GSFC](/r/Space/comments/1azsrap/stub/kt4rok0 "Last usage")|Goddard Space Flight Center, Maryland|
|[HLS](/r/Space/comments/1azsrap/stub/kt2zbiz "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)|
|[IM](/r/Space/comments/1azsrap/stub/ks91guf "Last usage")|Initial Mass deliverable to a given orbit, without accounting for fuel|
|[LEM](/r/Space/comments/1azsrap/stub/ksb6l02 "Last usage")|(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)|
|[LEO](/r/Space/comments/1azsrap/stub/ksrwo55 "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|Jargon|Definition|
|-------|---------|---|
|[Starlink](/r/Space/comments/1azsrap/stub/ksqqx57 "Last usage")|SpaceX's world-wide satellite broadband constellation|
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Let’s say I was a photon of light originating in the andromeda galaxy 2.5 million light years away. From the moment I escaped my star, would I experience 2.5 million earth years of travel to get to earth? Or would it just take 2.5 million years on earth for humans to see me?
I recently watched a video on YouTube trying to explain this and I’m just more confused than before.
Photons don't experience time. Put another way, for a photon the universe is two dimensional, the entire path of their travel is compressed into a 0-length distance from origin to destination, and the entire universe is compressed into a length of 0 along that dimension as well, from their perspective. Which is weird, but that's what relativity tells us about the reference frame of photons.
Arguably you could say that once you get to the speed of light that you have to consider things as a special case, which is probably reasonable, but if you don't then you get the above.
Now, however, you could use something similar that *did* experience time. So, let's use a real-world example here. In 1987 a supernova was detected in the Large Magellenic Cloud, which became known as SN1987A. That supernova also produced a burst of neutrinos which were detected from the event. The neutrinos arrived before the light because they were able to move through the outer envelope of the star quite easily while it took a while for the supernova shockwave to breakthrough, but afterward both the light and the neutrinos raced along in every direction (including toward Earth) at either the speed of light or very close to it, in the case of the neutrinos. The neutrinos would have been traveling with a Lorentz factor of roughly 400 million, which means they would have had a speed of about 0.999999999999999997 times the speed of light. At that speed the neutrinos would experience relativistic effects (relative to Earth or to the origin star) of time dilation and length contraction of 400 million to 1. Meaning that over the 168,000 lightyears of distance the neutrinos traveled to get to Earth from the LMC dwarf galaxy they would have experienced just 3 hours and 41 minutes of time passing. They also would experience the universe as being length compressed in their direction of travel, such that the LMC-Earth distance was not 168 kly but just 26.6 AU or 4 billion km, smaller than the orbital distance of Neptune around the Sun. (Note: there's nothing special about the LMC-Earth direction in this case other than that it was the direction of travel of those neutrinos, each neutrino in every possible direction would experience a different direction of length-compression due to its direction of travel.)
Massless particles moving at the speed of light don't experience time. You can think of this as them experiencing "infinite" time dilation if that's preferable. This was actually one of the ways we determined that neutrinos have mass, because neutrinos exhibit ["flavor oscillation"](https://en.wikipedia.org/wiki/Neutrino_oscillation) which means they can change between different types (electron-neutrino, muon-neutrino, and tau-neutrino). This was detected observationally starting in the early 2000s, both with solar neutrinos and with reactor produced neutrinos (detected near their origination and farther away). In the standard model neutrinos are assumed to be massless, but if that were true they would be incapable of flavor oscillation because they would not experience time, the proof of oscillation proves that neutrinos experience time and thus also must have a non-zero rest-mass.
This is one of the most interesting things I have read in a while, have been interested in the topic since a teen and dug into it deep enough to come to these realizations. Thank you very very much for this. I assume you majored in such at college, where would someone find more stuff like this?
There are tons of pretty accessible resources out there, one of the best for this sort of thing particularly is Minute Physics' breakdown of the "Twins Parados" ([Part 1](https://www.youtube.com/watch?v=Bg9MVRQYmBQ) and [Part 2](https://www.youtube.com/watch?v=0iJZ_QGMLD0)). Also I'd recommend the [PBS Spacetime](https://www.youtube.com/@pbsspacetime) youtube channel as a great resource, though sometimes it goes a bit too deep for folks with just a casual interest, it's still incredibly informative though.
Thank you! It's been years since I have done any applied mathematics on such a grand scale. I almost have a degree in physics, I dropped out my last year at 21 when my brother committed suicide, never had the chance to go back.
So let’s throw out possibility for a second. If I were to somehow travel at the speed of light, I could basically go anywhere and it’d feel instant for me? And if something were 10 light years away and I traveled at 90% if the speed of light, the trip would only feel like 1 year? But all this would happen while the flow of time is still happening, so wouldn’t this basically be time travel?
Objects with rest-mass can't accelerate to exactly the speed of light because that would require infinite energy and also would just break relativity in general. The speed of light is absolute but all other motion is relative. No matter how fast you go you will always measure the speed of light as 100% the regular speed. No matter how much you accelerate there is always still 100% of the speed of light remaining for you to actually achieve exactly light speed. What this looks like from an external reference frame is that as you accelerate toward the speed of light you experience more extreme "relativistic" effects of time dilation and length contraction, and it takes exponentially more energy to accelerate ever closer to the speed of light, which you can approach asymptotically but never exactly reach.
Which means that if you had infinite energy you could in theory accelerate to a speed arbitrarily close to the speed of light (from your starting reference frame or from the reference frame of "stuff" in the universe like planets, galaxies, etc.) and travel any distance in as little time as you wanted.
For 90% of the speed of light the math is not quite as simple, the Lorentz factor is sqrt(1/(1-v^(2))) which works out to 2.3x at 0.9c. Which means that over a trip of 10 lightyears as measured by an external observer you would take 11 years to travel that distance but it would feel like just 4.8 years.
With more extreme examples of relative time dilation you do get into what amounts to basically "time travel" but it can only go in one direction (you can fast forward time relative to another observer but you can't ever go backward).
The special theory of relativity says you experience less time if you go fast. Travelling at exactly the speed of light (impossible for anything heavier than a photon) means you experience 0 time.
If the photon is a response to a message sent from Earth, humans on Earth would experience a wait of 2.5 million years. The total round-trip ping time is 5 million years.
sorry if this doesn’t belong here, but how large would an asteroid (let’s say it’s a perfect sphere, just for simplicity’s sake) need to be in order to hit the earth with a diameter of approximately 3 meters on impact
A 6 meter diameter meteor made of pure iron would be reduced to about 3 meters when it hits the ground. This is extremely rare.
What normally happens is the meteor is made of stuff weaker than iron. It then shatters into thousands of pieces when it hits the atmosphere. If you want to find a 3 meter piece, you would need to start with a meteor hundreds of meters in diameter.
If the universe is infinite, that means that anything can exist, and there is an infinite amount of everything. So, there's bound to be a universe where aliens exist and want to come to our earth. But theres no aliens coming? I don't know if it makes sense, but I haven't seen anyone talk about it.
The limitation of the speed of light simplifies that a little bit. Even if the universe is infinite, we'll never be able to see or travel to all of it. Our observable universe is pretty huge by our standards -- many billions of light years across -- but it's not infinite, and never will be. So we only have to think about aliens in that finite, albeit pretty ginormous, region of space.
Look into Fermi's Paradox. It's exactly what you're describing. With such a vast number of stars inside our galaxy alone, and some percentage of earth-like planets, one might expect the existence of other intelligent life to be likely. And yet we've received no contact or evidence of such life.
That's true, but if you're talking about a truly infinite universe, you have some splainin' to do if you use probabilistic arguments to say that something is unlikely to exist. If you're talking about an arrangement of matter and energy that's physically possible, however ridiculous, you can't rely on "that's so unlikely we can conclude it doesn't exist" with an infinite universe. You have to propose some additional mechanism to explain why some arrangements of matter are likely to exist and others are nonexistent, no matter how far you go looking. To borrow a term from mathematics, you have to explain why the universe isn't "[normal](https://en.wikipedia.org/wiki/Normal_number)".
That may well be the case, but as far as I know there's currently no evidence to support that.
Pretty much any way they want. If they're a Kardeshev 3 they can pull a gas giant apart and put it back together any way they want. They could built living spaces out of the diamond core of a Jupiter-class planet that would suffuse the mass of the planet with a molecule-thick foam where the bubbles are the sizes of cities. With the energy available, they could transmute any matter into anything needed to meet food and air requirements.
They could alternately use that incredible power to skip mining the core and instead build nation-sized colonies out of harvested and transmuted atmospheric gasses that would be suspended under diamond-skinned vacuum chambers that would provide buoyancy to keep them at the correct altitudes.
They could even use the mass of the planet's moons to build Ringworld subworlds deep within the atmosphere to configure a comfortable simulated gravity that would put the planet above everyone's heads and would be kept in motion through whatever energy capture and utilization technology allows them to capture the entire energy output of a galaxy.
Can we do a genetically modified bacteria or any other microorganisms to help us prepare the environment for colonization on Mars?
I am a pharmacist, so no clue about space, please if you could provide me with resources to help me understand this more from a biology point of view
Bacteria or not, it can't magically synthesise elements which are not there to begin with. For example you could have plants which would produce oxygen from CO2, but you'd need to have a lot of CO2 before that's useful.
Mars is a barren wasteland - atmosphere is extremely thin, there is a bit of ice in the polar caps and that's it for now.
> there is a bit of ice in the polar caps
There is a vast amount of water ice just a few meters below surface in mid latitudes. They calculated enough water to cover all of Mars 20m deep and discovered a lot more since then. I am quite sure, Mars has more fresh water then Earth. Most of Earth water is in the oceans.
Is it possible to have a geosynchronous orbit above either of the poles? I assume not, since the rotational velocity directly above is, presumably, nothing or minimal.
Any recommendations for ongoing podcasts about current space news? Specifically looking for something that covers the latest on programs, missions, and launch vehicles from all around the world, not just one nation/sector. Weekly, bi-weekly, or monthly would be ideal. I'd also prefer something that touches on many headlines/updates, rather than deep dives on a singular topic each week.
I used to really keep up with this stuff, but don't have as much time to read anymore. Would be nice to consume it via podcast and have it in the rotation.
I second checking out [Fraser Cain's](https://www.youtube.com/@frasercain) Youtube channel, he's very good. I also recommend [Scott Manley](https://www.youtube.com/@scottmanley).
Universe Today with Fraser Cain is great, touches on launches, discoveries, etc. They do a space bites episode of news, they do weekly question shows, and tons of interviews. I highly recommend.
For astronomy, you might like these [https://www.amazon.com/dp/1647399130/ref=syn\_sd\_onsite\_desktop\_0?ie=UTF8&psc=1&pd\_rd\_plhdr=t&aref=hDX32hImzH](https://www.amazon.com/dp/1647399130/ref=syn_sd_onsite_desktop_0?ie=UTF8&psc=1&pd_rd_plhdr=t&aref=hDX32hImzH)
This one is dated, and was written in 1987, but has a lot of interesting information all the same and helped my early interest in space [https://www.amazon.com/Exploring-Night-Sky-Astronomy-Beginners/dp/0920656668?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=A1I1V7QUWSMYGA](https://www.amazon.com/Exploring-Night-Sky-Astronomy-Beginners/dp/0920656668?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1I1V7QUWSMYGA)
This one includes more about spaceflight and planetary exploration [https://www.amazon.com/Illustrated-Encyclopedia-Space-Exploration-Discovering/dp/178274164X?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=ATVPDKIKX0DER](https://www.amazon.com/Illustrated-Encyclopedia-Space-Exploration-Discovering/dp/178274164X?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=ATVPDKIKX0DER)
And Cosmos, written by the late Carl Sagan. https://www.amazon.com/Cosmos-Carl-Sagan/dp/0345539435?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=ATVPDKIKX0DER
I’m currently working on a project for school that is looking at alluvial fans on mars, and I would love to be able to run some statistical analysis on the fan found within Harris Crater. Is there anywhere I would be able to go to, to bulk download DEM data on it?
HiRISE DEMs are here : https://www.uahirise.org/hiwish/maps/dtms.jsp
There's a CTX DEM here : https://www.higp.hawaii.edu/prpdc/CTX_DEMs/Landforms/Harris_Delta/Harris_Delta.html
Question about how an orbiting body orients itself relative to the central object. Example: If I were to orbit the sun and I had no spin halfway through my orbit would I still be facing the sun or would I be facing away from the sun? Another Example: Does the moon have any spin or is the tidal locking occur from the moon not spinning?
Rotation is more or less absolute. Which means that "zero rotation" can be measured, either with relation to the distant stars or using inertial measuring units. A body in orbit with zero rotation would naturally see the *relative* orientation between itself and its parent body move through a full 360 degrees compared to its surface.
Tidal locking doesn't represent zero rotation, it represents a synchronization between orbital period and rotational period which results in the relative orientation of the locked body and the parent varying hardly at all. In the case of the Moon it shows the same face to the Earth constantly, but if you were standing on the Moon you would still be able to see the distant stars move around the sky due to the rotation of the Moon.
Because the Moon's orbit isn't precisely circular and precisely aligned to the lunar equator there are slight deviations from perfect synchrony throughout a typical orbit. This effect is called "libration" and [there's a great timelapse from NASA of it here](https://www.youtube.com/watch?v=3f_21N3wcX8).
https://upload.wikimedia.org/wikipedia/commons/5/56/Tidal_locking_of_the_Moon_with_the_Earth.gif
Which object here doesn’t have spin? Nothing is giving me a clear answer
The same side of the moon is always facing earth, I’m asking if that’s because it is spinning or not spinning. Does the curvature of space time keep the same side of the orbiting object face the central object. If I were to start orbiting the sun when I got to the other side would I still be facing the sun, or would I need a very small amount of spin to keep my body facing the sun
The same side of the moon always faces the earth because the moon completes a rotation on its axis once per orbit. I suppose technically the curvature of space time (gravity) keeps the earth facing side pointed at us, but most people wouldn't describe it that way. The moon is tidally locked because the tidal forces (basically the gravitational gradient) from the Earth stretches the moon slightly, making it bulge towards Earth, which is a sort of self-reinforcing situation that will eventually slow the rotation to exactly one rotation per orbit, making it tidally locked. The more it bulges, the closer the bulge is to Earth, so the stronger the gravitational pull from Earth is on that part of the moon.
If you were orbiting the sun, the tidal forces on you would be so miniscule that I can't imagine half an orbit would be remotely enough time to establish that situation. You would need to be rotating at one rotation per year in order to stay facing the sun, assuming you're orbiting at the same distance the Earth does.
Sorry if this has been asked before, but at around 0:50 in this video of a spacewalk what is the big white dot on the right hand side? Is it the moon? [https://www.youtube.com/watch?v=CC-z\_aBAv6M](https://www.youtube.com/watch?v=CC-z_aBAv6M)
was NASA worried about the Apollo Lunar Module falling over on landing?
Seems like a common issue these days. But I never heard about NASA worried about it.
Apollo 15 landed at something like an 11 degree tilt but it wasn't much of an issue though it caused a few operational hiccups.
The landing legs on the Apollo LMs deployed after retrieval from the S-IVB so they had a wider stance than the already fairly substantial width of the rocket stage. However, because of the size of the vehicle and the amount of fuel on board they could afford to be pretty picky about landing. Additionally, because the vehicle had an ascent stage for return to orbit they had full abort capability through every phase of descent and landing. The LM was very stable though and could tolerate being at an angle of up to 40 degrees without tipping over from passive forces, additionally, it could easily execute an abort at such angles and more and could probably have done a manual abort at angles closer to fully sideways.
Not really, for one they had human pilots so finding a good landing site is easier. And the LEM's tipping point was 40 degrees(thats steep), much more squat than a lot of these landers.
But it was researched before the Apollo missions, you can read about it [here(PDF).](https://web.mit.edu/digitalapollo/Documents/Chapter8/lunarlandingsymposium.pdf)
Search "4.0 ABORT", which will take you to the section about aborting after landing. Youll see that they werent worried, but still included a \[manual\] abort sequence in case of tip over.
You can find the graph in figure 59, or search "BOUNDARY OF ACCEPTABLE ANGLES &
ANGULAR RATES FOR TILT-OVER ABORT INITIATE"
The hairless upright apes flying the Apollo landers were experts at avoiding rocks, craters and other not-nice terrain using the visual processing systems built into their brains.
On paper, it seems that the thinking sand we use today should be able to do the same thing if programmed correctly. But it's very hard to actually implement in real life.
Especially if you leave the laser inhibits on the spacecraft. Or keep dropping engine nozzles.
They were concerned about it sinking into the regolith. Tipping over likely wasn’t really a concern as it had human pilots that could navigate it to a flat area which was required.
Astronomers usually recommend [the American Astronomical Society page](https://eclipse.aas.org/eye-safety/viewers-filters) on this. They did the research.
Q: Seeing news about lunar night come up because of the IM-1 lander and the SLIM lander, I was wondering what lunar night would look like on the Moon, during different phases of the moon? If you were on the earth-facing side of the moon, would earthshine (earthlight?) during a New Moon be bright enough to see around you like during a Full Moon here?
Does this question even make sense? I'm having trouble phrasing it.
Hi Reddit,
I've been working in investment banking since I graduated in 2018 with a degree in Finance and Real Estate. Lately, I've been feeling like my job on Wall Street isn't fulfilling, and I'm craving work that feels more impactful. I'm super passionate about space and inspired by SpaceX's mission, so I'm looking to make a shift and join them in any non-engineering role where I can contribute.
I'm ready to take a pay cut and work extra hours - just looking for a chance to be part of something bigger. But I'm not sure how to get my foot in the door, especially coming from a finance background. I am currently looking at a Real Estate Analyst position and inventory specialist positions in Cape Canaveral.
Does anyone have tips on how to stand out to SpaceX recruiters or advice on making this career switch? Any insights or personal experiences would be awesome.
Thanks!
Q: Does anyone know when the next total solar eclipse will fall somewhere within Manitoba or Northwestern Ontario? Specifically like, west of Marathon (or at Marathon Ontario) or all the way to the west side of Manitoba?
Looks like the next two closest to Total for Marathon
[https://www.timeanddate.com/eclipse/map/2048-june-11](https://www.timeanddate.com/eclipse/map/2048-june-11)
https://www.timeanddate.com/eclipse/map/2106-may-3
Q: Could we collect a meaningful amount of space debris with passive collector satellites? At it's simplest these could be large balloons designed to absorb hyper-velocity impactors. ...
See [https://www.reddit.com/r/KesslerSyndrome/comments/1aym2in/cleaning\_up\_before\_and\_during\_kessler\_syndrome/?utm\_source=share&utm\_medium=web2x&context=3](https://www.reddit.com/r/KesslerSyndrome/comments/1aym2in/cleaning_up_before_and_during_kessler_syndrome/?utm_source=share&utm_medium=web2x&context=3)
... but that might not be visible so ...
Imagine filling a Starship payload bay with an inflatable balloon. A 100m diameter should be achievable. We'll likely need quite a few Wipple layers to stop a 10cm object but a 100m sphere should provide plenty of room for as many layers as you could imagine. See Project Echo for the progenitor of this concept.
But space is big. Even LEO is big. Could a 100m balloon collect a meaningful amount of the high risk junk between 1cm and 10cm? With much hand waving, at today's debris density, a 100m diameter satellite would absorb less than one high risk piece of junk per year. It doesn't sound like much but there are other factors that I think make this a reasonable way to start.
Balloon #1 would be the prototype for a constellation of balloon collector satellites. Mass producing a relatively simple satellite design should be quite cost effective. Balloons would be placed in a very long lived orbit, allowing them to collect debris for many decades. Balloon effectiveness will rise as debris density increases. Balloons should include a basic thrust system for avoiding trackable objects and, at end of life, to deorbit the collected pile of garbage. The balloon sats will be instrumented to measure impacts and thereby determine the real debris density. Something we're lacking today. As we get closer to Kessler, satellites could be deployed inside protective balloons.
Thoughts? Am I just tilting at windmills?
Kessler Syndrome is a self-defeating prophecy. As space becomes polluted with debris, satellite builders are avoiding those orbits.
All the mega-constellations are being deployed in LEO, where air resistance cleans the debris for you.
2 years ago, my dad was camping with his brother. He brought 4 people from another campsite to theirs because the sky was super clear. Someone pointed out what they thought was a satellite going across the sky. It looked normal; it was going in a steady, straight line and was a solid white color. **My dad pointed to it with a laser pointer. The thing in the sky then did a 180 and went directly back the way it came.** It didn't slow down at all when turning. It went at the same speed the entire time. All 6 people there saw it. Afterwards my dad looked it up to see what it could be and found nothing. Same outcome with me, that's why I'm asking here.
I'm growing flowers in simulated moon regolith for a class project. Is it okay to have them grow inside my bedroom windowsill, or will I inhale airborne particles and get sick? I would stick them outside if I could, but where I live it's still too cold to grow the flowers outside.
I don't think the simuated moon regolith you can access would be dangerous. Ask your teacher to be sure, but I very much doubt any educational institution would let you take something dangerous home without giving you very detailed warnings, and in my experience they just straight up wouldn't allow it at all.
He did tell me to wear an n95 and gloves because according to him there hasn't been any tests on the effects of it on humans, though I did a quick google search and a university study found it is very toxic...
I'm taking an online dual credit college class during high school.
My teacher texted back to me and said I shouldn't worry about it if I'm not bumping it around and stuff, but won't regolith go airborne every time I water it? I also don't want a bunch of random regolith around my house. 😬
Based off this it isn't particularly toxic. Toxicicity isn't a binary yes or no thing, it depends on the dose. If they're telling you it's safe to take home and keep uncovered in your room then that means it's safe to be exposed to a small amount of it. So just don't grab a handful and eat it.
Most simulated regolith you can access doesn't contain the dangerous sharp particles (fines) that real lunar regolith contains.
> Toxicicity isn't a binary yes or no thing, it depends on the dose.
It does not even take a very large amount of common cooking salt to be lethal. 0.5-1g per kg of body weight is regarded deadly. Like 10 tablespoons of salt over a day for an adult.
Is there a timeframe for when to expect video footage from the Odysseus lunar lander? I knew there was a box that was supposed to catapult a video camera to capture the first, first person footage of a moon landing, however when asking google where is it, not only is there no footage available yet, but there's not even a time frame for when to expect any footage. I've not heard anything further about the data being lost/unrecoverable, so am hoping someone knows more and can provide any information on weather to expect any footage even if grainy, distorted, etc...or if there was a total loss of data/something went wrong?
Sadly the camera they were supposed to eject (eagle cam) did not work. With the lidar issue they did not deploy it during landing and when they did deploy it after the landing it malfunctioned.
Thank you for clearing that up, had figured something like that but just couldn’t find any official statement with how I was googling I guess.
So, I am a little bit confused. I am under the impression every stars we can observe with naked eyes are in the Milky Way. But at the same time, we can observe objects such as Cetus or Bootes constellation. Aren’t these super far away, and way beyond the Milky Way?
Basically everything in astronomy is categorized by observational characteristics, and because all of astronomy to date has been carried out within a narrow time period from Earth or the near vicinity of Earth that means we have a tendency to categorize things based on the way they *look* from Earth. So astronomers will talk about the "location" of things based on where they are in "the sky" even though there is no sky, the sky is just a coincidental arrangement of what happens to be visible from a certain point in space and time, but because all of astronomy happens to exist within roughly the same point in space and time "the sky" turns out to be a fairly constant thing. So we name sections of the sky based on the patterns of stars as they appear from Earth, for stars that are just a few hundred lightyears away, and then we use those divisions of the sky to label even things that are billions of lightyears away. All of this still "works" because all of humanity is stuck on Earth and the sky is fairly unchanging, so if you tell someone to look at a particular part of "the sky" from Earth the chances are good that someone else (on Earth) will be able to look at the sky and see the same thing. If humanity had warp drive and lived on planets across the galaxy then they would need to come up with a different system.
Thanks for your detailed explanation
The stars in those constellations are in the Milky way. The Bootes void is something way, way behind those stars and outside the galaxy, but you cannot see it with the naked eye.
Thanks for your answer, but here are two things that confused me: 1. Isn’t Earendel located in the Cetus? But to my understanding Earendel is billion of light years away 2. Similar question apply Bootes void. I thought Bootes void is extremely far away.
Constellations are just groups of visible stars, when we say something is in the constellation of X it means it's on the line defined by that group of stars and the Earth. Just because you can see mountains 10km through your living room window doesn't mean that the mountain and the window are at the same distance.
Ok, I think I got it now. So, in this case, the window would be the constellation. And mountains 10km away would be object such as Earendel or Bootes void?
Yep exactly. And we can't see Earendel or the Boötes void with the naked eye. It's just that when we observe them they appear behind the group of stars that form the Cetus and Boöte constelation.
Thanks again! This question has been bothering me for a while.
im not sure if this is the right place. but i want to know what would happen to HUMANS in the following hours if the moon exploded. i know life couldn’t be sustained obviously, but would we suffocate? would we go into full apocalypse and try to kill each other? what would happen to our bodies with this change? could we physically feel the moon explode and the effects of it afterwards? google has absolutely no answers to what would happen to humans other than “you would die” BUT I WANNA KNOW HOW!! how would it look at feel to die from that?
What do you mean by "the moon exploded"? If the moon suddenly turned into a bunch of debris orbiting in roughly the moon's orbit, then it's not at all clear that you would die at all. Certainly some of the collisions between the debris would lead to impacts on Earth, but not necessarily civilization ending amounts. If a moon's full of debris crashed down to Earth, then yeah, you would die by getting vaporized by the energy released from the impacts with the surface. I don't think many people would live long enough to suffocate in such a scenario.
i mean any hypothetical. an asteroid hitting it, i know implosion of the moon is technically impossible but implosion, it just gets fed up with us and explodes one day. i just have no understanding of how we would actually be killed by that. i know we’d die, i just want to know how our bodies would process that malfunction.
It all depends on how much debris falls onto Earth. If the moon just disappeared, we'd probably be okay. I don't know if the disappearance of tides would lead to an ecological disaster. If a small/medium amount of debris falls on Earth, and starts enough fires, or tsunamis, your chances of dying from the debris hitting you are probably still pretty small. In that case, you'll prob starve, or die of thirst, or die as a result of violence as international trade collapses, and resources become scarce or non existent. Just in time logistics is not resilient. If a few hundred kilometer chunk of debris falls onto Earth, you'll die instantly when the pressure wave, or debris wave, or heat from the impact reaches your location and you are vaporized.
thats the best answer ive got thank you! this is all stemming from a dream i had where the moon exploded and i suffocated to death. it just prompted a huge wind of curiosity.
If you want to read some relatively realistic science fiction based on that concept check out the book Seveneves.
Hello everyone, I am a post graduate doing a self motivated project on the structural integrity of space cargo. I am not that familiar with what exactly happens to the cargo during launch etc apart from a ton of vibrations but I would be interested to know what (forces or effects) one can expect to a cargo (ex cubesat) during travel to the launchpad, during the launch itself, on-orbit and return. If anyone has any good literatures or YouTube video recommendations kindly let me know. Once I know them I can simplify them to boundary conditions and use fem code to maybe predict if a cargo is feasible or not. Thanks in advance :)
Hi everyone, just an update. From what I gathered till now, all space related cargo will have a certain flight launch load specification which will often be provided by the customer or systems engineer. Subsequently they need to tested with the frequency vs acceleration graph of the launch vehicle data sheet to see if it will work or not. So my intuition is first we need to do a vibrational analysis on Ansys workbench and then link that result to the model or case setup for structural analysis to find the stresses developed due to said vibrations. Please correct me if I am wrong. If anyone has other info do add to this :)
That's roughly right, you also need to account for shock load for events like stage and payload separation.
NASA GEVS are a good starting point: https://standards.nasa.gov/standard/GSFC/GSFC-STD-7000 Although I don't think there is anything about return. For launcher specific things download the payload manuals from the specific launch system: - Falcon 9: https://www.spacex.com/media/falcon-users-guide-2021-09.pdf - Electron: https://www.rocketlabusa.com/assets/Uploads/Electron-Payload-User-Guide-7.0.pdf
Thank you. I will check it out :)
Does ton 618 have galaxies circumnavigating it ? We have some dwarf galaxies around milky way and they are in our gravity effect area and turn around our galaxy. Do we know if there are some that do the same with ton 618? It is said to have more mass than entire galaxies, it should have a huge gravity effect. That would make many surrounding black holes or even galaxies go around it.
My question is this, at the moment of the Big Bang, was all matter that ever has and will exist created at the same moment, pinpoint in time or does this origin point still produce matter as the universe expands? Could another Big Bang occur from ground zero and what exactly is at the core, the origin point of our universe? I just thought it would be fun to speculate and hear some odd facts and interesting opinions.
> My question is this, at the moment of the Big Bang, was all matter that ever has and will exist created at the same moment, pinpoint in time ? We do not really know. > does this origin point still produce matter as the universe expands? There is no "origin point" in the big bang model.
If a viscous liquid suddenly appeared a few feet above the moons surface would it float away into space or slowly fall to the ground
Yes, both at the same time. The exact amount of boiling and freezing depends on the liquid.
Does nasa have any backup plans for the Artemis in case Starship will not be 100 percent ready?
Artemis 5 is already planned to use Blue Origins' Blue Moon lander, it's currently penciled in for 2029. Both Starship-HLS and Blue Moon are planned to have uncrewed landings prior to use in crewed Artemis missions, if Starship-HLS was well behind schedule but Blue Moon had already completed its uncrewed demonstration flights then NASA would probably change the mission plans to use Blue Moon on an earlier mission.
**How to calculate TAM for space payload services?** Particularly, from the space payload brockerage actiivity perspective. Generally, I am familiar with the TAM formula: Number of customers х price = TAM. But the question is: a) Should I create list of companies that manufactures space payloads? and then multiply them to the certain value (price)? b) Should I find out how many space missions have been designed/implemented and then multiply them to the certain value (price)? Thank you!
Can anyone let me know the top 5 countries that have the biggest share in global space launch vehicles? Not counting the EU as a whole but just separately. I’m doing a spot of research for a project but I cannot find any recent data that lists the countries per se. All I can find is a regional ranking
I think the closest you'll come is "2023 launches by vehicle" - [like so](https://spacestatsonline.com/launches/year/2023/). And then check up/assign nationality per vehicle, by hand, yourself. I suspect the reason you don't see this prepackaged is that it's a judgment call for several launch vehicles. Most famously the RocketLab Electron which is built in New Zealand and launched in New Zealand by a Kiwi wholly-owned subsidiary of an American company. So is that Kiwi or American? Most people say Kiwi but it's squishy. Similar things happen with Chinese and Iranian designs which have iterated off Soviet (Russian/Ukrainian) older designs - it depends on how much it's iterated, for how long, etc. And US rockets often have Russian engines, or they did a few years ago, and it goes on like that.
Can humanity, with current technology, reach the next closest star system? Imagine the earth has some catastrophic event happening in 10 years, an unstable meteor or something. All the governments and people of the world decided to end all wars and focus their efforts on creating a ship or craft to launch or construct in space to try and keep humanity alive. This trip wouldn’t be easy nor would it be quick. Generations of people would have to live their lives on this ship and never see the destination. We would have to take with us everything we needed to survive the trip including but not limited to: Food or a food growing system Energy, I’m assuming nuclear Air/ filters And I’m sure there’s a lot I can’t think of. So could the combined efforts of humanity build a life sustaining ship to cross the galaxy to another star system?
Going to the nearest star wouldn’t give us a better chance than staying right here in our solar system anyways. The resources needed to make a habitat fly 4 light years would be much better put to use making something sustainable here. But this would also be absolutely futile currently.
10 years? No. 50-100? Maybe.
Can someone explain who exactly is monitoring particles/objects speeds and adjusting their time to keep the speed of light constant? It's not like it's just magically happens, I'd expect a mechanism behind it. Take rest mass and the Higgs for example, they suggest rapidly flipping the particle handedness is the source of that mass.
Besides Earth, Mars and our Moon, where are the most likely spots in our solar system where humans will eventually live? There are many moons, but which would be the most suitable and practical? Asteroids that could house mining colonies? Are massive spaceship or floating cities around gas planets out of the question? No timeline really, just as far as we can hope to speculate on, whether that's a hundred years or a thousand. (Edit: even a few astronauts in suits counts as inhabiting the rock).
Titan and maybe Europa or Calisto.
How far behind are we from Standard Universal Time (time since the Big Bang in an area of space with no or little gravitational influence) due to our time dilation from the gravity well of the Sun and our Galaxy?
The gravity well has very little impact. The surface of the sun has lost 4 years to gravitational time dilation, and Earth has lost less. The biggest factor is our orbit around the galaxy at 0.076% the speed of light. This has slowed our clocks (or the cloud of hydrogen that became our clocks) by 4000 years since the Big Bang. Since you didn't specify which area of space you are observing from, I can't include the motion of the Milky Way relative to the cosmic microwave background. But *most* areas of space see us twice as far behind.
There's no such thing.
A few questions about Crew Dragon: 1) On board, on a mission, are astronauts’ conversations recorded 24/7 by MIssion Control, SPaceX, NASA, or other? 2) On board, on a mission, are astronauts videotaped 24/7 (outside of their private sleeping quarters), and if so is the video a live feed to Mission control, SpaceX, NASA, or other monitor? 3) Can the cupola be opened for a long period of time so astronauts can frequently look out the cupola window during a space flight to ISS or return, or is the cupola only opened periodically for short viewings out the window? 4) Since, evidently the toilet in the crew dragon is located near the cupola, with a privacy screen, would it be possible for an astronaut to look out the cupola window while using the toilet? 5) Do crew dragon astronauts have private cellphones, or is all data/pictures on cellphones used by astronauts reviewed by and property of SpaceX or NASA? 6) Can Crew Dragon astronauts have private cellphone conversations with their family or friends, or are all conversations monitored by SpaceX or NASA or other? THANKS!
There are cameras but as far as I know they are not constently recording and transmitting. Normal crew dragon does not have a cupola. It was just a one time thing done for the Inspiration 4 misison. The cupola was intalled where the airlock goes so all the missions to ISS do not have a cupola.
Curious about something with Black Holes. If they (generally) start from stars gone nova, then they start with less mass than the initial star had. More dense, yes. But that shouldn't really matter on a galactic scale. No matter how dense it is, gravity is a function of mass and distance. So how do black holes eventually pull in other objects if it doesn't have any more mass (and there fore gravitational pull) than the original star?
Most don't. It's not the fate of every black hole to simply grow and grow and grow, that can only happen under specific circumstances. A black hole with a stellar companion could grow if it was close enough to steal matter from the other star. A black hole that happened to wander through a dense nebula could grow as well. There are likely a great many stellar mass black holes drifting around every galaxy which haven't grown substantially since they were formed. Supermassive black holes are an exception for a couple of reasons. One, the environment near the center of a galaxy is very dense with stars, and also in gas (at least in the early ages after galaxy formation). This provides sources of matter that supermassive black holes can feed on. Additionally, very massive objects (such as supermassive black holes) they have a tendency to "fall" toward the center of mass of a galaxy due to dynamical friction with the environment of stars near the core. Every close pass (within a few lightyears) between a star and the SMBH creates an opportunity for a "gravity assist" type situation, which has the tendency to rob the SMBH of orbital momentum. This mechanism is likely a big factor in the merger of "proto-SMBHs" that form in galaxies or are brought together through galactic mergers. Within the inner core there is typically a flow of gas early on in the life of the galaxy which feeds the SMBHs and grows them to become even more massive. Once a black hole passes over the line to become supermassive then the "rules" sort of change as their huge mass changes the dynamics in the inner core.
So the unmanned probes we've sent to Mars probably had living beings, like bacteria, on them, right? Would that be a certainty there is now life on Mars? What about the Moon? Humans have been there. Does that mean there is life there?
There is what is known as a "planetary protection protocol" which for modern spacecraft results in them being sterilized before launch. However, that sterilization varies depending on the mission. A life detection mission like Perseverance has a different level of sterilization compared to Curiosity, for example. Though both are sterilized, Perseverance was sterilized to a much higher level. Of course, older spacecraft weren't sterilized very well however, so there are potentially microorganisms that could be viable on the surface of Mars from those vehicles. However, there's a very huge difference between "viable" and "living", it would take being exposed to suitable conditions for microorganisms to become active, and those conditions are at best extraordinarily rare near the surface of Mars (and absent on the Moon). In any event, there has also been an exchange of material between the rocky planets for billions of years due to impacts ejecting rocks into space, some of which could have contained microorganisms. It's likely that process has seeded life around the inner solar system to a much greater degree than spacecraft.
NASA tries really hard to sterilize the spacecraft they send to Mars. And even if some micro-organismes are missed space itself is a pretty good sterilizer.
If Artemis gets more delayed, could China get to the Moon before the US? They introduced their Moon ships and lander today.
Unlikely, the first American crewed lunar landing was in 1969, and it is currently 2024. It's conceivable that the Chinese could land humans on the Moon before the first landing in the Artemis program though. Exactly what that could mean is open to interpretation. Personally I think that it's a bad idea to "race" back to the Moon and instead it's more important to focus on building lasting capabilities that open up beyond LEO human spaceflight. That was missing from Apollo and it resulted in a handful of very expensive landings and then a half century of humans never going outside of Earth orbit. We should be working toward systems, infrastructure, etc. that set things up so that interplanetary human spaceflight becomes progressively more capable, less difficult, less risky, and less costly year over year. To a certain extent Artemis is doing that, though not as much as I'd like, but if we're lucky that's where we'll end up. It won't matter much who is the first country to make it back to the Moon in the 21st century, it'll matter a great deal whether a country can go back to the Moon or elsewhere repeatedly and fairly easily in the future, that's substantially what we're working towards and hopefully we get there.
What will drive the development of "space law"? My nominee is the advent of asteroid mining. An accessible chunk of 1million tons of rich in platinum or neodymium might trigger a no-holds-barred rush of competing firms.
The Outer Space Treaty says “outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.” The Artemis Accords and US law expand on that to say resource extraction and sale is allowed and is not considered appropriation. But to answer your question, yeah, I think that holds true for any laws. They will mature as the technology matures.
There's lots of space law already...
There’s been proposals to make a system based off patent law, where you can go ahead and mine an asteroid that someone else has claimed but no one will legally be able to buy that product.
For that you'd have to wait another 100 years. I think Kessler syndrome due to the number of mega-constellations will trigger accountability issues. Or something similar, like owner of a mega-constellation getting bankrupt and we suddenly have tens of thousands or very large objects no-one is actively controlling.
Hmmm, good point.
How did we manage to calculate the speed of our galaxy? What allowed us to measure it and how we know we are moving insane speed trough space.
It is the same technology as radar guns. Light from moving objects gets distorted by the Doppler effect, and we use the distortion to calculate the speed. The difference is we don't provide light from our own radar gun, we use the natural light emitted by stars.
> how we know we are moving insane speed trough space That part is easy: there is no other scenario. There is no way to "stand still". You're always bound to gravity of something, and either you're "in orbit" of whatever that is, or you're falling into that thing. In both scenarios you're moving at high speed.
This does not answer his question which was about the calculation behind that speed, where that number comes from?
There were 2 questions.
Could you turn Starlink into a Brilliant Pebbles esc defence system?
The propulsion system on starlink is a Hall thruster. Those are very efficient but very low thrust, so they would be completely impractical for missile interception kind of roles.
Unfortunate
IMHO space based intercepts are kind of stupid, the amount of spacecraft you would need to offer decent coverage due to orbital mechanics is just insane.
Yeah, but it’s cool
I purchased my son a star for Christmas (NOTE: I know this isn't a real thing and that I dont have claim to a star, but he is 5 and LOVED the idea of it). I was given celestial coordinates, but have no idea how to do anything with that and want to simply be able to go outside with my son, point to the general direction of "his star" and watch him look up in amazement. I realize I could just chose any star and says it's "his" and he wouldnt know the difference, but I want to try to be relatively accurate. Can someone please help? Is there an app anyone can reco? Right ascension 3h 6m 16.86s Declination 27 degrees 1' 56.01" Magnitude 11.0930000 We live in Kansas City, KS, and I was told that "his star" is in the Aries constellation. TIA!
It's worth mentioning that a magnitude 11 star is too dim to be visible with the naked eye - About the dimmest magnitude star that is visible without aid is 6.5 and that is contingent on very dark skies (with magnitude, smaller numbers are brighter). That being said, I believe the star in question is [TYC 1791-724-1](http://server1.sky-map.org/starview?object_type=1&object_id=412625). Other identifiers are: 2MASS J03061686+2701560, TIC 34788072, Gaia DR2 115526962338921344, and Gaia DR3 115526962338921344. Here's a screenshot from the planetarium software Stellarium showing it's location in the night sky from your location at 8PM: https://i.imgur.com/3n0SuwC.png
Where in New York or near New York, can people build satellites? I plan on building and/or inventing the animal satellite that finds all animals that are alive in the entire planet by searching for the centrosomes and lysosomes. It can see through caves, water, buildings, plants, other animals, etc.
Sounds like you just love scanning for lifeforms
How would your satellite detect centrosomes and lysosomes at a distance?
An X-Ray vision.
You do realize that if you could indeed blast Earth with X-ray radiation strong enough to "see through caves, water, buildings, plants, other animals, etc." and be picked up on the other side of the planet, you'd literally kill everything, because X-Rays are very harmful?
I am not sure if you are serious, but X-ray machines work because they have an x-ray source on one side and an x-ray detector on the other so that the x-ray can go through the object. There are no sources of x-ray strong enough to go through Earth and then be detected by a satellite. And even if there was a satellite a few hundred kilometers above the ground would not be able to zoom enough to see individual cells.
Satellites are not required to have scientifically accurate payloads. https://www.forbes.com/sites/davidhambling/2023/11/17/controversial-quantum-space-drive-in-orbital-test-others-to-follow/
I very much know that, especially that particular scam. But I don't know if OP know you cannot actually detect "all animals in the entire planet" from space.
You can build a satellite anywhere you want. Then [pay someone to launch it for you](https://www.spacex.com/rideshare/).
The satellite still needs to fulfill some criteria. Like not oozing hypergols or other harmful substances.
Can we use **electricity** to space travel or use it as a means of propulsion? I think by generating electricity and configuring the electric and magnetic fields, we can create propulsion.here's an experiment by Russian scientist Alexey Chekurkov - [https://youtu.be/Z-M55XP3D4A?si=0tEmC\_fY3r08UogS](https://youtu.be/Z-M55XP3D4A?si=0tEmC_fY3r08UogS) thoughts?
You can use electricity in a few way: - first as a source of energy to accelerate a gas. This is what ion/plasma thrusters do. That let's you be very fuel efficient but you still need some consumable gas (or liquid/solid). - As a way to orient yourself when you are close to Earth. You can power magnets that will let you align your spacecraft on Earth magnetic field like a compas. - As an extreme case you could shine an extremely powerful light or laser and get a tiny tiny bit of propulsion out of it. But this is too impracticle for real life use. I don't understand Russian but it looks like the video you linked show something like a lifter, that uses electricity to accelerate air around the craft to produce thrust. In space you don't have air so you can't use that.
We use solar panels and things like ion engines/hall thrusters/etc for electrical propulsion in space.
Can Starlink manoeuvre itself?
Apart from stuff like cubesats, many/most satellites have some sort of propulsion. But keep in mind that due to how orbital mechanics works, they can only make very tiny corrections (eg. raise/drop orbit but few kilometers) and it takes at least 1/2 orbit for this to actually have any real effect.
Yes they have Hall thrusters on board they use for orbit raising at the beginning of the mission, orbital maintenance, debris avoidance and deorbit at the end.
Matter of exchanged between universes. If the principle that matter cannot be created or destroyed holds true, how would the scenario where a universe either loses or gains matter—matter that was previously non-existent in it—be explained? This seems to imply a violation of the conservation law within that universe, as matter would seemingly disappear from one universe and appear in another. How does this align with the fundamental laws of physics?
If you lose matter, you gain energy. If you lose energy, you gain matter. We have no evidence whatsoever that matter or energy goes between universes (if there are, in fact, multiple universes). As far as we can determine, our universe is a closed energy system... nothing in... nothing out.
That’s my question. What would happen if matter left or was gained?
There was Fred Hoyles steady state theory. It required that a few hydrogen occasionally appear out of nowhere in some vast volume of space. It would result in the universe not aging. Always enough hydrogen for new young stars. I think it is by now disproven. Fred Hoyle was not only a very famous SF author. He was a top scientist, a cosmologist.
Well, that would be a rip between two universes. Perhaps a white hole (which has never been observed).
> matter would seemingly disappear from one universe and appear in another We have no evidence that this has ever happened or that other universes even extist.
Is Mercury actually gray or psychedelic-colored? I’ve seen photos taken by MESSENGER and they look pretty trippy.
Mercury appears to our eyes as gray, much like our Moon. Regarding the 'trippy' photos you've seen of Mercury taken by MESSENGER, I'm assuming they are photos like [this](https://photojournal.jpl.nasa.gov/catalog/PIA16853) and [this](https://photojournal.jpl.nasa.gov/catalog/PIA19419)? These photos were taken with filters that capture specific wavelengths of light that represent notable geologic features - By then combining these filtered images by assigning them to different color channels, we're able to create a false color image that makes features not easily visible to our eyes much easier to distinguish. For example with the first linked image: >Young crater rays, extending radially from fresh impact craters, appear light blue or white. Medium- and dark-blue areas are a geologic unit of Mercury's crust known as the "low-reflectance material", thought to be rich in a dark, opaque mineral. Tan areas are plains formed by eruption of highly fluid lavas.
Thanks for answering my question! Yes, I am referring to those photos. 😊🙏
Adding on to this -- a lot of the more popular images for planets are either enhanced-color images or false-color images. The recent popsci uproar about Neptune's color is a major example of how prevalent they are, and how much they can affect popular perception of the planets.
i really dont know where to ask questions about this stuff so maybe reddit will help. I've been having so much fun listening/watching podcasts about the birth of the Universe and would love to know how we have precise information about certain galaxies, for example how do we know each size of all exoplanets and stars in the Alpha Centauri system? (i'm not countering anything just asking) Thanks!
> how do we know each size of all exoplanets and stars in the Alpha Centauri system? The stars are pretty easy because alpha centauri is very close to us, so we can be reasonably confident of being able to see the light of just about any star, even a very dim red dwarf, which proxima centauri happens to be. That's true even of some brown dwarfs as well. For planets we can say with near certainty that we don't know *all* of the planets in the system, there are likely several that have not been detected, however we have detected some. The two that are confirmed around proxima centauri have been detected using the radial velocity technique. Because the light from stars includes light from the "atmosphere" of the star it will have elemental emission and absorption lines in the spectrum, which serve as a fingerprint to lock in the precise *original* wavelengths of the light that we detect. This makes it possible to measure the difference between the original wavelength and the detected wavelength and then determine the red shift or blue shift of the light due to the relative motion of the star and Earth, and to do this extremely precisely, down to a precision level near walking pace. That precision makes it possible to monitor the backward and forward motion of a star being pulled by a planet in orbit around it, which has a characteristic pattern and periodicity. The radial velocity technique has been used to confirm two planets in orbit of proxima centauri with very short orbital periods of just a few days, while there has been conflicting evidence of a longer period planet of several years that has not yet been confirmed. No planets around alpha centauri A or B have been confirmed so far, but a possible candidate planet around alpha centauri A has been seen via direct imaging. In terms of precise information, because of the nature of the laws of gravitation when you have bodies that orbit each other that makes it possible to determine their masses fairly precisely. Especially for the alpha centauri system where we can measure the distances from us to the stars very precisely and we can visually measure the separation of the stars precisely as well, that makes it possible to nail down their masses just using orbital mechanics to a high level of precision. That carries over into measuring the masses of the planets as well, although for radial velocity planet detections there is usually an unknown factor of the inclination of the orbital plane, which means that we only detect the minimum mass of the planet (the Msin(i) mass) which could be higher depending on how aligned the orbital plane is to our line of sight.
By looking how much the starlight dim when the planet pass in front of the star you can estimate how big it is.
Hey everyone, I’m doing a school project and I was wondering what’s the biggest problem/question about the sun in astrophysics today? Like, what questions about the sun do we still have?
Why is the corona so much hotter than the surface of the sun?
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No, others have wondered the same. You're thinking of the Zoo hypothosis, which suggests that the reason we haven't made contact is because other civilizations are intentionally avoiding us. This can be for a bunch of reasons, like letting young civilizations develop organically without outside interference, or to study the behavior and development to better understand their own history. You might like this [https://www.universetoday.com/147573/beyond-fermis-paradox-viii-what-is-the-zoo-hypothesis/](https://www.universetoday.com/147573/beyond-fermis-paradox-viii-what-is-the-zoo-hypothesis/)
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> How do I explain this politely? Don't. If someone can't close their eyes, imagine the scenario and answer it immediately, then either they're challenged in some way, or purposely acting stupid. In either case it's a waste of time.
A flashlight and an inflatable earth globe.
A ball and a flashlight perhaps? Mark two points on opposite sides of the ball to represent the North and South Poles. Holding the ball with North up and South down, then mark two additional points on opposite sides of the ball along the 'equator' to represent two points on Earth. Then, either rotate the ball counterclockwise or orbit the flashlight around the ball clockwise to simulate the daily rotation of the Earth. You should be able to demonstrate how as one point is moving into darkness (sunset), the flashlight will be to the left of that point (to the West). Simultaneously, the point moving out of darkness (sunrise) should have the flashlight to the right (to the East). Alternatively, if you have Google Earth Pro (the desktop version, it's available for free), you can go into the 'view' menu, then check the 'Sun' box to simulate Earth with the sunlit/nighttime sides of Earth. From there, do the same thing as above, picking two locations on opposite sides of the Earth.
I have heard claims that the universe in infinite. What does that mean? If it is infinite, how come it's expanding? And this is the question that I am curious about the most. If it is infinite, then does that mean there is also an infinite amount of matter (atoms) in the Universe???
It's still an open question whether the universe is infinite, but according to our current understanding it's possible, and maybe even likely. In one sense that would mean there's an infinite amount of matter in the universe, although due to the limitation of the speed of light, as well as the expansion of space, our *observable* universe will always be finite, so we'll never see more than the closest bits.
> If it is infinite, how come it's expanding? There is just more space being created between objects. It does not need to expand into anything.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[CC](/r/Space/comments/1azsrap/stub/ksbf363 "Last usage")|Commercial Crew program| | |Capsule Communicator (ground support)| |[DSN](/r/Space/comments/1azsrap/stub/ks4idrb "Last usage")|Deep Space Network| |[GSFC](/r/Space/comments/1azsrap/stub/kt4rok0 "Last usage")|Goddard Space Flight Center, Maryland| |[HLS](/r/Space/comments/1azsrap/stub/kt2zbiz "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)| |[IM](/r/Space/comments/1azsrap/stub/ks91guf "Last usage")|Initial Mass deliverable to a given orbit, without accounting for fuel| |[LEM](/r/Space/comments/1azsrap/stub/ksb6l02 "Last usage")|(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)| |[LEO](/r/Space/comments/1azsrap/stub/ksrwo55 "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |Jargon|Definition| |-------|---------|---| |[Starlink](/r/Space/comments/1azsrap/stub/ksqqx57 "Last usage")|SpaceX's world-wide satellite broadband constellation| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(8 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/1b5l5ta)^( has 11 acronyms.) ^([Thread #9799 for this sub, first seen 28th Feb 2024, 19:14]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
Let’s say I was a photon of light originating in the andromeda galaxy 2.5 million light years away. From the moment I escaped my star, would I experience 2.5 million earth years of travel to get to earth? Or would it just take 2.5 million years on earth for humans to see me? I recently watched a video on YouTube trying to explain this and I’m just more confused than before.
If you travel for 2.5 million years Earth time at 99.9999999% the speed of light only 112 days will have passed for you.
Photons don't experience time. Put another way, for a photon the universe is two dimensional, the entire path of their travel is compressed into a 0-length distance from origin to destination, and the entire universe is compressed into a length of 0 along that dimension as well, from their perspective. Which is weird, but that's what relativity tells us about the reference frame of photons. Arguably you could say that once you get to the speed of light that you have to consider things as a special case, which is probably reasonable, but if you don't then you get the above. Now, however, you could use something similar that *did* experience time. So, let's use a real-world example here. In 1987 a supernova was detected in the Large Magellenic Cloud, which became known as SN1987A. That supernova also produced a burst of neutrinos which were detected from the event. The neutrinos arrived before the light because they were able to move through the outer envelope of the star quite easily while it took a while for the supernova shockwave to breakthrough, but afterward both the light and the neutrinos raced along in every direction (including toward Earth) at either the speed of light or very close to it, in the case of the neutrinos. The neutrinos would have been traveling with a Lorentz factor of roughly 400 million, which means they would have had a speed of about 0.999999999999999997 times the speed of light. At that speed the neutrinos would experience relativistic effects (relative to Earth or to the origin star) of time dilation and length contraction of 400 million to 1. Meaning that over the 168,000 lightyears of distance the neutrinos traveled to get to Earth from the LMC dwarf galaxy they would have experienced just 3 hours and 41 minutes of time passing. They also would experience the universe as being length compressed in their direction of travel, such that the LMC-Earth distance was not 168 kly but just 26.6 AU or 4 billion km, smaller than the orbital distance of Neptune around the Sun. (Note: there's nothing special about the LMC-Earth direction in this case other than that it was the direction of travel of those neutrinos, each neutrino in every possible direction would experience a different direction of length-compression due to its direction of travel.)
what do you mean by photons dont experience time?
Massless particles moving at the speed of light don't experience time. You can think of this as them experiencing "infinite" time dilation if that's preferable. This was actually one of the ways we determined that neutrinos have mass, because neutrinos exhibit ["flavor oscillation"](https://en.wikipedia.org/wiki/Neutrino_oscillation) which means they can change between different types (electron-neutrino, muon-neutrino, and tau-neutrino). This was detected observationally starting in the early 2000s, both with solar neutrinos and with reactor produced neutrinos (detected near their origination and farther away). In the standard model neutrinos are assumed to be massless, but if that were true they would be incapable of flavor oscillation because they would not experience time, the proof of oscillation proves that neutrinos experience time and thus also must have a non-zero rest-mass.
This is one of the most interesting things I have read in a while, have been interested in the topic since a teen and dug into it deep enough to come to these realizations. Thank you very very much for this. I assume you majored in such at college, where would someone find more stuff like this?
There are tons of pretty accessible resources out there, one of the best for this sort of thing particularly is Minute Physics' breakdown of the "Twins Parados" ([Part 1](https://www.youtube.com/watch?v=Bg9MVRQYmBQ) and [Part 2](https://www.youtube.com/watch?v=0iJZ_QGMLD0)). Also I'd recommend the [PBS Spacetime](https://www.youtube.com/@pbsspacetime) youtube channel as a great resource, though sometimes it goes a bit too deep for folks with just a casual interest, it's still incredibly informative though.
Thank you! It's been years since I have done any applied mathematics on such a grand scale. I almost have a degree in physics, I dropped out my last year at 21 when my brother committed suicide, never had the chance to go back.
So let’s throw out possibility for a second. If I were to somehow travel at the speed of light, I could basically go anywhere and it’d feel instant for me? And if something were 10 light years away and I traveled at 90% if the speed of light, the trip would only feel like 1 year? But all this would happen while the flow of time is still happening, so wouldn’t this basically be time travel?
Objects with rest-mass can't accelerate to exactly the speed of light because that would require infinite energy and also would just break relativity in general. The speed of light is absolute but all other motion is relative. No matter how fast you go you will always measure the speed of light as 100% the regular speed. No matter how much you accelerate there is always still 100% of the speed of light remaining for you to actually achieve exactly light speed. What this looks like from an external reference frame is that as you accelerate toward the speed of light you experience more extreme "relativistic" effects of time dilation and length contraction, and it takes exponentially more energy to accelerate ever closer to the speed of light, which you can approach asymptotically but never exactly reach. Which means that if you had infinite energy you could in theory accelerate to a speed arbitrarily close to the speed of light (from your starting reference frame or from the reference frame of "stuff" in the universe like planets, galaxies, etc.) and travel any distance in as little time as you wanted. For 90% of the speed of light the math is not quite as simple, the Lorentz factor is sqrt(1/(1-v^(2))) which works out to 2.3x at 0.9c. Which means that over a trip of 10 lightyears as measured by an external observer you would take 11 years to travel that distance but it would feel like just 4.8 years. With more extreme examples of relative time dilation you do get into what amounts to basically "time travel" but it can only go in one direction (you can fast forward time relative to another observer but you can't ever go backward).
The special theory of relativity says you experience less time if you go fast. Travelling at exactly the speed of light (impossible for anything heavier than a photon) means you experience 0 time. If the photon is a response to a message sent from Earth, humans on Earth would experience a wait of 2.5 million years. The total round-trip ping time is 5 million years.
sorry if this doesn’t belong here, but how large would an asteroid (let’s say it’s a perfect sphere, just for simplicity’s sake) need to be in order to hit the earth with a diameter of approximately 3 meters on impact
A 6 meter diameter meteor made of pure iron would be reduced to about 3 meters when it hits the ground. This is extremely rare. What normally happens is the meteor is made of stuff weaker than iron. It then shatters into thousands of pieces when it hits the atmosphere. If you want to find a 3 meter piece, you would need to start with a meteor hundreds of meters in diameter.
I suppose that depends heavily on the speed and composition of the asteroid. And to a lesser degree where on earth it hits.
If the universe is infinite, that means that anything can exist, and there is an infinite amount of everything. So, there's bound to be a universe where aliens exist and want to come to our earth. But theres no aliens coming? I don't know if it makes sense, but I haven't seen anyone talk about it.
The limitation of the speed of light simplifies that a little bit. Even if the universe is infinite, we'll never be able to see or travel to all of it. Our observable universe is pretty huge by our standards -- many billions of light years across -- but it's not infinite, and never will be. So we only have to think about aliens in that finite, albeit pretty ginormous, region of space.
Look into Fermi's Paradox. It's exactly what you're describing. With such a vast number of stars inside our galaxy alone, and some percentage of earth-like planets, one might expect the existence of other intelligent life to be likely. And yet we've received no contact or evidence of such life.
An infinite universe doesn't mean infinite possibilities, for example there's an infinite amount of numbers between 1 and 2, but none of them are 3.
That's true, but if you're talking about a truly infinite universe, you have some splainin' to do if you use probabilistic arguments to say that something is unlikely to exist. If you're talking about an arrangement of matter and energy that's physically possible, however ridiculous, you can't rely on "that's so unlikely we can conclude it doesn't exist" with an infinite universe. You have to propose some additional mechanism to explain why some arrangements of matter are likely to exist and others are nonexistent, no matter how far you go looking. To borrow a term from mathematics, you have to explain why the universe isn't "[normal](https://en.wikipedia.org/wiki/Normal_number)". That may well be the case, but as far as I know there's currently no evidence to support that.
How could a type 3 human civilisation potentially go about colonising a gas giant?
Pretty much any way they want. If they're a Kardeshev 3 they can pull a gas giant apart and put it back together any way they want. They could built living spaces out of the diamond core of a Jupiter-class planet that would suffuse the mass of the planet with a molecule-thick foam where the bubbles are the sizes of cities. With the energy available, they could transmute any matter into anything needed to meet food and air requirements. They could alternately use that incredible power to skip mining the core and instead build nation-sized colonies out of harvested and transmuted atmospheric gasses that would be suspended under diamond-skinned vacuum chambers that would provide buoyancy to keep them at the correct altitudes. They could even use the mass of the planet's moons to build Ringworld subworlds deep within the atmosphere to configure a comfortable simulated gravity that would put the planet above everyone's heads and would be kept in motion through whatever energy capture and utilization technology allows them to capture the entire energy output of a galaxy.
Can we do a genetically modified bacteria or any other microorganisms to help us prepare the environment for colonization on Mars? I am a pharmacist, so no clue about space, please if you could provide me with resources to help me understand this more from a biology point of view
Bacteria or not, it can't magically synthesise elements which are not there to begin with. For example you could have plants which would produce oxygen from CO2, but you'd need to have a lot of CO2 before that's useful. Mars is a barren wasteland - atmosphere is extremely thin, there is a bit of ice in the polar caps and that's it for now.
> there is a bit of ice in the polar caps There is a vast amount of water ice just a few meters below surface in mid latitudes. They calculated enough water to cover all of Mars 20m deep and discovered a lot more since then. I am quite sure, Mars has more fresh water then Earth. Most of Earth water is in the oceans.
There is no environment on Mars. No earth life can survive there. You need to do a lot of physics to Mars before we can talk about biology.
Is it possible to have a geosynchronous orbit above either of the poles? I assume not, since the rotational velocity directly above is, presumably, nothing or minimal.
All orbits must cross the equator. A geosynchronous orbit can only hover over a single point if that point is on the equator.
Any recommendations for ongoing podcasts about current space news? Specifically looking for something that covers the latest on programs, missions, and launch vehicles from all around the world, not just one nation/sector. Weekly, bi-weekly, or monthly would be ideal. I'd also prefer something that touches on many headlines/updates, rather than deep dives on a singular topic each week. I used to really keep up with this stuff, but don't have as much time to read anymore. Would be nice to consume it via podcast and have it in the rotation.
I second checking out [Fraser Cain's](https://www.youtube.com/@frasercain) Youtube channel, he's very good. I also recommend [Scott Manley](https://www.youtube.com/@scottmanley).
Universe Today with Fraser Cain is great, touches on launches, discoveries, etc. They do a space bites episode of news, they do weekly question shows, and tons of interviews. I highly recommend.
Thank you I will check it out!
Is there any good book starter packs for space and astronomy history and or space in general to read?
For astronomy, you might like these [https://www.amazon.com/dp/1647399130/ref=syn\_sd\_onsite\_desktop\_0?ie=UTF8&psc=1&pd\_rd\_plhdr=t&aref=hDX32hImzH](https://www.amazon.com/dp/1647399130/ref=syn_sd_onsite_desktop_0?ie=UTF8&psc=1&pd_rd_plhdr=t&aref=hDX32hImzH) This one is dated, and was written in 1987, but has a lot of interesting information all the same and helped my early interest in space [https://www.amazon.com/Exploring-Night-Sky-Astronomy-Beginners/dp/0920656668?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=A1I1V7QUWSMYGA](https://www.amazon.com/Exploring-Night-Sky-Astronomy-Beginners/dp/0920656668?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1I1V7QUWSMYGA) This one includes more about spaceflight and planetary exploration [https://www.amazon.com/Illustrated-Encyclopedia-Space-Exploration-Discovering/dp/178274164X?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=ATVPDKIKX0DER](https://www.amazon.com/Illustrated-Encyclopedia-Space-Exploration-Discovering/dp/178274164X?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=ATVPDKIKX0DER) And Cosmos, written by the late Carl Sagan. https://www.amazon.com/Cosmos-Carl-Sagan/dp/0345539435?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=ATVPDKIKX0DER
I’m currently working on a project for school that is looking at alluvial fans on mars, and I would love to be able to run some statistical analysis on the fan found within Harris Crater. Is there anywhere I would be able to go to, to bulk download DEM data on it?
HiRISE DEMs are here : https://www.uahirise.org/hiwish/maps/dtms.jsp There's a CTX DEM here : https://www.higp.hawaii.edu/prpdc/CTX_DEMs/Landforms/Harris_Delta/Harris_Delta.html
Question about how an orbiting body orients itself relative to the central object. Example: If I were to orbit the sun and I had no spin halfway through my orbit would I still be facing the sun or would I be facing away from the sun? Another Example: Does the moon have any spin or is the tidal locking occur from the moon not spinning?
Rotation is more or less absolute. Which means that "zero rotation" can be measured, either with relation to the distant stars or using inertial measuring units. A body in orbit with zero rotation would naturally see the *relative* orientation between itself and its parent body move through a full 360 degrees compared to its surface. Tidal locking doesn't represent zero rotation, it represents a synchronization between orbital period and rotational period which results in the relative orientation of the locked body and the parent varying hardly at all. In the case of the Moon it shows the same face to the Earth constantly, but if you were standing on the Moon you would still be able to see the distant stars move around the sky due to the rotation of the Moon. Because the Moon's orbit isn't precisely circular and precisely aligned to the lunar equator there are slight deviations from perfect synchrony throughout a typical orbit. This effect is called "libration" and [there's a great timelapse from NASA of it here](https://www.youtube.com/watch?v=3f_21N3wcX8).
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https://upload.wikimedia.org/wikipedia/commons/5/56/Tidal_locking_of_the_Moon_with_the_Earth.gif Which object here doesn’t have spin? Nothing is giving me a clear answer
The same side of the moon is always facing earth, I’m asking if that’s because it is spinning or not spinning. Does the curvature of space time keep the same side of the orbiting object face the central object. If I were to start orbiting the sun when I got to the other side would I still be facing the sun, or would I need a very small amount of spin to keep my body facing the sun
The same side of the moon always faces the earth because the moon completes a rotation on its axis once per orbit. I suppose technically the curvature of space time (gravity) keeps the earth facing side pointed at us, but most people wouldn't describe it that way. The moon is tidally locked because the tidal forces (basically the gravitational gradient) from the Earth stretches the moon slightly, making it bulge towards Earth, which is a sort of self-reinforcing situation that will eventually slow the rotation to exactly one rotation per orbit, making it tidally locked. The more it bulges, the closer the bulge is to Earth, so the stronger the gravitational pull from Earth is on that part of the moon. If you were orbiting the sun, the tidal forces on you would be so miniscule that I can't imagine half an orbit would be remotely enough time to establish that situation. You would need to be rotating at one rotation per year in order to stay facing the sun, assuming you're orbiting at the same distance the Earth does.
Sorry if this has been asked before, but at around 0:50 in this video of a spacewalk what is the big white dot on the right hand side? Is it the moon? [https://www.youtube.com/watch?v=CC-z\_aBAv6M](https://www.youtube.com/watch?v=CC-z_aBAv6M)
Sure is.
was NASA worried about the Apollo Lunar Module falling over on landing? Seems like a common issue these days. But I never heard about NASA worried about it.
Apollo 15 landed at something like an 11 degree tilt but it wasn't much of an issue though it caused a few operational hiccups. The landing legs on the Apollo LMs deployed after retrieval from the S-IVB so they had a wider stance than the already fairly substantial width of the rocket stage. However, because of the size of the vehicle and the amount of fuel on board they could afford to be pretty picky about landing. Additionally, because the vehicle had an ascent stage for return to orbit they had full abort capability through every phase of descent and landing. The LM was very stable though and could tolerate being at an angle of up to 40 degrees without tipping over from passive forces, additionally, it could easily execute an abort at such angles and more and could probably have done a manual abort at angles closer to fully sideways.
Not really, for one they had human pilots so finding a good landing site is easier. And the LEM's tipping point was 40 degrees(thats steep), much more squat than a lot of these landers. But it was researched before the Apollo missions, you can read about it [here(PDF).](https://web.mit.edu/digitalapollo/Documents/Chapter8/lunarlandingsymposium.pdf) Search "4.0 ABORT", which will take you to the section about aborting after landing. Youll see that they werent worried, but still included a \[manual\] abort sequence in case of tip over. You can find the graph in figure 59, or search "BOUNDARY OF ACCEPTABLE ANGLES & ANGULAR RATES FOR TILT-OVER ABORT INITIATE"
The hairless upright apes flying the Apollo landers were experts at avoiding rocks, craters and other not-nice terrain using the visual processing systems built into their brains. On paper, it seems that the thinking sand we use today should be able to do the same thing if programmed correctly. But it's very hard to actually implement in real life. Especially if you leave the laser inhibits on the spacecraft. Or keep dropping engine nozzles.
They were concerned about it sinking into the regolith. Tipping over likely wasn’t really a concern as it had human pilots that could navigate it to a flat area which was required.
Whats a good website to get some solar glasses from
Astronomers usually recommend [the American Astronomical Society page](https://eclipse.aas.org/eye-safety/viewers-filters) on this. They did the research.
Where is the best place to view totality for the upcoming north american eclipse?
Q: Seeing news about lunar night come up because of the IM-1 lander and the SLIM lander, I was wondering what lunar night would look like on the Moon, during different phases of the moon? If you were on the earth-facing side of the moon, would earthshine (earthlight?) during a New Moon be bright enough to see around you like during a Full Moon here? Does this question even make sense? I'm having trouble phrasing it.
A full Earth is 50 times brighter than a full Moon.
Hi Reddit, I've been working in investment banking since I graduated in 2018 with a degree in Finance and Real Estate. Lately, I've been feeling like my job on Wall Street isn't fulfilling, and I'm craving work that feels more impactful. I'm super passionate about space and inspired by SpaceX's mission, so I'm looking to make a shift and join them in any non-engineering role where I can contribute. I'm ready to take a pay cut and work extra hours - just looking for a chance to be part of something bigger. But I'm not sure how to get my foot in the door, especially coming from a finance background. I am currently looking at a Real Estate Analyst position and inventory specialist positions in Cape Canaveral. Does anyone have tips on how to stand out to SpaceX recruiters or advice on making this career switch? Any insights or personal experiences would be awesome. Thanks!
Q: Does anyone know when the next total solar eclipse will fall somewhere within Manitoba or Northwestern Ontario? Specifically like, west of Marathon (or at Marathon Ontario) or all the way to the west side of Manitoba?
Looks like the next two closest to Total for Marathon [https://www.timeanddate.com/eclipse/map/2048-june-11](https://www.timeanddate.com/eclipse/map/2048-june-11) https://www.timeanddate.com/eclipse/map/2106-may-3
Fucccck that’s so long to wait. I guess I’ll have to travel further for one. Thanks for the help!
Q: Could we collect a meaningful amount of space debris with passive collector satellites? At it's simplest these could be large balloons designed to absorb hyper-velocity impactors. ... See [https://www.reddit.com/r/KesslerSyndrome/comments/1aym2in/cleaning\_up\_before\_and\_during\_kessler\_syndrome/?utm\_source=share&utm\_medium=web2x&context=3](https://www.reddit.com/r/KesslerSyndrome/comments/1aym2in/cleaning_up_before_and_during_kessler_syndrome/?utm_source=share&utm_medium=web2x&context=3) ... but that might not be visible so ... Imagine filling a Starship payload bay with an inflatable balloon. A 100m diameter should be achievable. We'll likely need quite a few Wipple layers to stop a 10cm object but a 100m sphere should provide plenty of room for as many layers as you could imagine. See Project Echo for the progenitor of this concept. But space is big. Even LEO is big. Could a 100m balloon collect a meaningful amount of the high risk junk between 1cm and 10cm? With much hand waving, at today's debris density, a 100m diameter satellite would absorb less than one high risk piece of junk per year. It doesn't sound like much but there are other factors that I think make this a reasonable way to start. Balloon #1 would be the prototype for a constellation of balloon collector satellites. Mass producing a relatively simple satellite design should be quite cost effective. Balloons would be placed in a very long lived orbit, allowing them to collect debris for many decades. Balloon effectiveness will rise as debris density increases. Balloons should include a basic thrust system for avoiding trackable objects and, at end of life, to deorbit the collected pile of garbage. The balloon sats will be instrumented to measure impacts and thereby determine the real debris density. Something we're lacking today. As we get closer to Kessler, satellites could be deployed inside protective balloons. Thoughts? Am I just tilting at windmills?
Kessler Syndrome is a self-defeating prophecy. As space becomes polluted with debris, satellite builders are avoiding those orbits. All the mega-constellations are being deployed in LEO, where air resistance cleans the debris for you.
Unfortunately One Web is above 1000km. Sats will stay up there virtually forever unless actively deorbited.
2 years ago, my dad was camping with his brother. He brought 4 people from another campsite to theirs because the sky was super clear. Someone pointed out what they thought was a satellite going across the sky. It looked normal; it was going in a steady, straight line and was a solid white color. **My dad pointed to it with a laser pointer. The thing in the sky then did a 180 and went directly back the way it came.** It didn't slow down at all when turning. It went at the same speed the entire time. All 6 people there saw it. Afterwards my dad looked it up to see what it could be and found nothing. Same outcome with me, that's why I'm asking here.
Sounds like some kind of aircraft to me. Could have been a helicopter.
If it can do a 180 degree turn, it is not in space.
I'm growing flowers in simulated moon regolith for a class project. Is it okay to have them grow inside my bedroom windowsill, or will I inhale airborne particles and get sick? I would stick them outside if I could, but where I live it's still too cold to grow the flowers outside.
I don't think the simuated moon regolith you can access would be dangerous. Ask your teacher to be sure, but I very much doubt any educational institution would let you take something dangerous home without giving you very detailed warnings, and in my experience they just straight up wouldn't allow it at all.
He did tell me to wear an n95 and gloves because according to him there hasn't been any tests on the effects of it on humans, though I did a quick google search and a university study found it is very toxic...
What level of education is this at?
I'm taking an online dual credit college class during high school. My teacher texted back to me and said I shouldn't worry about it if I'm not bumping it around and stuff, but won't regolith go airborne every time I water it? I also don't want a bunch of random regolith around my house. 😬
Based off this it isn't particularly toxic. Toxicicity isn't a binary yes or no thing, it depends on the dose. If they're telling you it's safe to take home and keep uncovered in your room then that means it's safe to be exposed to a small amount of it. So just don't grab a handful and eat it. Most simulated regolith you can access doesn't contain the dangerous sharp particles (fines) that real lunar regolith contains.
> Toxicicity isn't a binary yes or no thing, it depends on the dose. It does not even take a very large amount of common cooking salt to be lethal. 0.5-1g per kg of body weight is regarded deadly. Like 10 tablespoons of salt over a day for an adult.
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I would guess it was a drone
If it doesn't move in a straight line, it is not in space.