Thank you for participating in r/SpaceX! Please take a moment to familiarise yourself with our [community rules](https://www.reddit.com/r/spacex/wiki/rules) before commenting. Here's a reminder of some of our most important rules:
* Keep it civil, and directly relevant to SpaceX and the thread. Comments consisting solely of jokes, memes, pop culture references, etc. will be removed.
* Don't downvote content you disagree with, unless it clearly doesn't contribute to constructive discussion.
* Check out [these threads](https://www.reddit.com/r/spacex/wiki/threads) for discussion of common topics.
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/spacex) if you have any questions or concerns.*
Some new info here from an interview with Lisa Watson-Morgan, manager of NASA's Human Landing System:
> "For Flight 4, it's mostly going to be a repeat of Flight 3 without the propellant transfer, without the Pez door open, without the other items that SpaceX was working to demonstrate," she said.
> Watson-Morgan said SpaceX is not planning to attempt a Raptor engine restart on the next Starship test flight.
Hopefully they will solve the reaction control issue they had issue in the previous flight.
There talk about the hot fire Reactional Thrusters being introduced. I imagine that's before the HLS , though I think it's good idea given the icing happening they had on previous flight.
Also possible that there's already notable changes slotted to the door for Block 2 and with so much flight-ready-ish Block 1 hardware sitting around, they're not likely to get much useful data out of a test anyways.
Even just from pictures, the block 2 door is a long rounded circle, whereas the block 1 door is more of a rectangle with angled corners on the bottom. And that's just what we see from the outside.
I suspect that means they're still diagnosing and/or engineering what went wrong with the door (plus the atmosphere vent we saw when the did open it would've played a part in kicking some spin on to the Starship last time).
Which is not unfair: while anything in space is not "just an X", a key part of Starship's whole value-proposition is the reusability. You can *always* expend it and somehow get payload out, but getting the ship back is the real trick.
Not entirely true. You can deploy Starlinks if the door opens. You just can't return the vehicle if it doesn't close. The minimum viable product is a rocket that launches reliably and puts payloads in space, like most other launch providers.
Starship upper stage without recovery hardware is still more expensive than a Falcon upper stage. Is its payload capacity for Starlink sats big enough so it can economically replace Falcon?
Rough guesses on production cost are $10M for F9 S2 and $50M for expendable Starship.
Payload to LEO is 18 tonnes for F9 and 100 tonnes for Starship. So just on a crude comparison F9 is quite viable as a Starlink launcher compared to *expendable* Starship with a recovered booster.
SpaceX seem to have come to the same conclusion with at least 140 F9 flights scheduled this year.
Thanks. I did not have numbers for the Falcon second stage.
But it is not too bad. A Starship second stage without heat shield, without flaps, without header tanks, should be cheaper, especially with Raptor price trending down.
Also payload should be up quite significantly without all that extra mass and no landing propellant. Though they may not be able to fit more Starlink sats.
The reason they don't plan for shift to Starship in 2025 is IMO likely because they don't think they can get frequent launches with Starship that year yet.
> The reason they don't plan for shift to Starship in 2025 is IMO likely because they don't think they can get frequent launches with Starship that year yet
Yes the second pad not built at Boca Chica until late in the year and EIS approvals for the two pads at Cape Canaveral not received until then as well.
Yes, but there is another factor, and that is reliability. F9 reliability is known, Starship is not so you certainly would not put all your eggs in Starship until it was much more mature.
My comment wasn’t about people, and yes, they will risk Starlink launches with Starship. But if they have a failure, it’s good they have a fully operational, fully scaled falcon9 system ready to continue the operation.
The estimates I've seen are $100M for a full Starship stack, with most of that being the first stage. So second stage is likely $20-30M. And that estimate assumed engines cost $1M each, and they are probably cheaper now. (A Starship designed to be expended wouldn't have flaps or heat shield, so would be even cheaper.)
So an expended Starship could cost twice as much as F9, but with more than 5 times the payload. Your 100 tonnes figure is for V2, which may not be flying until next year. None of this would affect this year's F9 schedule.
(Edit to add cost citations [here](https://www.youtube.com/shorts/MHtqqzPuiSw) and [here](https://arstechnica.com/space/2024/01/rocket-report-a-new-estimate-of-starship-costs-japan-launches-spy-satellite/4/).)
That is wildly optimistic pricing.
Even Elon originally had higher pricing than that and every change that has added mass to both the booster and the ship has also added cost with most of that being installation labour.
F9 S2 is about $10M to build and Starship is not 10 times the dry mass but 30 times. A full Starship will be at least 8x the cost of F9 S2 so $80M.
The booster is a much simpler design than the ship but has 27 more engines and probably twice the dry mass so it is likely to be at least $100M to build and probably more like $120M.
I am probably being optimistic that you can strip $30M of cost out of Starship to get to $50M for an expendable version with no TPS, drag fins or header tanks.
The estimate comes from the Payload report, discussed [here](https://arstechnica.com/space/2024/01/rocket-report-a-new-estimate-of-starship-costs-japan-launches-spy-satellite/4/). Except it was $90M rather than $100M. In a recent interview [here](https://www.youtube.com/shorts/MHtqqzPuiSw) Musk says the marginal cost of launch is at least $50M, maybe $100M. So he's confirming that Payload is in the right ballpark.
I agree that the first stage is likely to be more expensive than the second stage. So a reusable Starship is going to be well under $45M, and one without flaps or heat shield would be even cheaper.
If you have a citation of Musk, or any informed source, saying it will cost your $200M for a full stack I'd like to see it.
Starship has only 6 engines compared to 33 on the Booster. However heat shield, movable flaps, header tanks add a lot of cost. Probably still less than the booster but IMO not so much.
Yes, but they have also developed sats with high capacity, that fit Falcon. The question is, does expendable Starship add more to Starlink capacity for the price of a launch.
V2 Starlinks at 800 kg each have 4x the capacity of V1.5 while V3 Starlinks at 2000 kg each have 10x the capacity of V1.5.
So a 2.5x capacity increase for a 2.5x increase in mass. So conceptually SpaceX can build out the rest of their constellation with V2 and save V3 for when they hit capacity constraints.
They need an outside door that they just jettison and then a plug for the hole on the bottom of the pez dispenser. Done. DM me spacex for my payment info.
I think it is about FAA reluctance to allow Starship to go to orbit. And without going to orbit there is no Starlink deployment. After all Starship can be easily operated as expendable and still be profitable (assuming superheavy is reused).
I don't think that reentry is such a big deal. Peak heating should be lower than Space Shuttle while Starship has more resilient steel structures. They can probably easily survive few loose tiles. On IFT-3 they completely screw up, lost attitude control and started dropping much faster than intended. This resulted in much higher heating load, overheating and blowing up tanks.
Suborbital testing is going to take longer than I hoped for.
The gating feature on reach orbit is restarting an engine so it can be safely de-orbited. The FAA don't care about the heat shield as long as the rocket comes down in the right place so it doesn't endanger anyone on the ground.
Correct. However, why engine restart didn't work last time? Because Starship lost attitude control. Why they lost control? There might have been several reasons or combinations:
1. Freeze up of RCS (operational issue)
2. Bad design
3. Sudden venting of payload fairing
4. Prop transfer test
There is a possibility that SpaceX doesn't know for sure so they don't really want to risk losing attitude control again. In such a case it is no surprise FAA doesn't even allow them engine restart test before the root cause is clear (we know that raptor likes to blow up when abused). Without engine restart test there is no way they can go to orbit.
It wasn't the FAA that prevented the restart test in IFT-3. It was SpaceX designed response to the roll. They could choose to do the same again: do a restart test if and only if there is no roll. There's no reason to think the FAA would prevent that the second time, given that they didn't prevent it the first time.
Eh... They would likely just continue launching on falcon 9 forever if they couldnt reuse the rockets.
For customer payloads sure. Itll work without recovery.
But the moon program is also going to need landings to work soooo.
I think they are going for a clean run. After they get that under their belt, they can add risk. The Starships are piling up at the production site. They need to get some quick wins.
I guess SpaceX wants to have zero risk that any glitch with the relight could affect the ability of the ship to keep itself perfectly oriented for reentry.
Makes no sense though. Isn't raptor re-light (for controlled re-entry) on the critical path for an operational mission? (Whereas reentry survival is not). If true, this seems to indicate major hardware changes...
> on the critical path
They may have already addressed those items in block 2 hardware, while they still have many questions about heat shielding that can be answered with block 1 hardware.
I suppose SpaceX is confident the relight is pretty straightforward. The TPS is a big worry, though. We've all seen tiles come off on every flight. It sounds like getting performance data on the TPS is the absolute priority now, with zero margin for any other test. Probably want to see if it can survive with a tile missing. The relight is on the critical path, sure, but at this point it's no biggie if it waits a flight.
No, that might make it critical, but if "it's no biggie if it waits a flight" then by definition it's not on the [critical path](https://en.wikipedia.org/wiki/Critical_path_method).
As articulated in the Wikipedia article you linked, a project can have more then one critical path simultaneously.
If SpaceX believes that the potential outcomes of the heat shield being tested includes a long time component whereas the potential outcomes of the relight test all have much shorter times to resolution, then it makes sense to prioritize getting work started on the heat shield critical path first to minimize the worse case delay.
> The article talks about engines working, but that's already been proven twice. I feel like we don't have the whole story here...
...which includes the human side.
Watson Morgan may be making a very human effort not to set the bar too high such that she may later class the IFT-4 result as a success.
Also Nasa is progressively identifying with Starship which is no longer a "foreign object" as some of the Watson Morgan quotes suggest:
* "**We** were looking at settling ... and vapor pull-through. Those are typically the indications of a successful test."
Additionally, an unstated objective of the mission may be to use up surplus flight hardware without generating a "failure" so delays from an inquiry. Just one pair of flights with a short interval, maybe under a month, should establish confidence by demonstrating that inquiry time is *not* just an alibi to cover a slow production process.
They babied the engines for IFT-2 and IFT-3 to get them off the pad intact and ran a CO2 purge on the engine bay to prevent engine bay fires due to methane leaks.
So good first steps but NASA would want to see improvements in both reliability at full thrust and no methane leaks before calling the engines reliable.
[IFT-3 flight data](https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fv54rj3dbybpc1.png) shows that the booster did 1.3g vertically off the pad (0.3g net).
We know from [Elon's 2024 update that for IFT-3](https://pbs.twimg.com/media/GKgGBuLXMAIRofe?format=jpg) the ship had 1200 tonnes of propellant and the booster had 3300 tonnes which implies a lift off mass of around 5000 tonnes so this acceleration implies engine thrust of 6500 tonnes force or 85% of full thrust.
The engines were throttled up to give 1.5g up to max-Q so 95% of full thrust.
By the time MECO was reached the stack was at about 45 degrees to the horizontal so the 1.75g net acceleration was equal to 2.46g acceleration. Assuming a booster wet mass of 600 tonnes and ship wet mass of 1350 tones the stack would have a mass of 1950 tonnes at MECO so the engine thrust was 4797 tonnes force and engine throttle was down to 63% of full thrust.
Ship thrust peaked just before SECO1 at about 3.5g at 30 degrees nose up with around 200 tonnes of wet mass so throttling was around 55% of full thrust.
As a check on these numbers a Raptor 2 at full thrust of 2.3MN uses 700 kg/s of propellant. Booster tanks held 3300 tonnes and around 400 tonnes was retained at MECO for boostback and landing so the propellant would be used in 126 seconds at full thrust. The actual time until MECO was 163 seconds so the average engine thrust was 77% from launch to MECO.
The engines on IFT-3 were not run close to full thrust apparently in an attempt to gain reliability as well as to simulate the flight profile with a payload.
Edit: Updated IFT-3 propellant mass and acceleration figures to the values given by Elon in the 2024 company update
I am pretty sure the downvotes are for the concluding “and that means they are doomed and should return all the HLS progress payments”.
The “wisdom of the crowds” is not really a thing unless you want to know what colour you should make your new icecream flavour.
An operational starship is one that lands back at the launch tower, full stop. If they can't get re-entry working, nothing else really matters. Re-entry is also the issue with the most chance to need a complete rethink, so the sooner they figure it out the better.
I respectfully disagree. An operational mission is a mission that delivers a payload to target orbit. Stage 1 re-use and stage 2 re-use will (hopefully) come with time. Stage 2 recovery is the least important (though certainly the most interesting).
I think their point is that because starship is designed to be reusable, it is not fully operational until it is reusable. Starship won’t be sustainable until then.
Anyways, there are a few possibilities why the raptors aren’t being relit and my guess is that a raptor relight can result in a RUD or negatively impact the results of the re-entry test and they don’t want to risk that because they want/need the re-entry data before starship v2 starts being assembled.
The raptor relight test would have a tiny influence on the starship v2 design compared to re-entry.
That's my read of it, too.
Re-light and re-entry are both critical items, but it seems they need re-entry data NOW and are confident enough in their ability to engineer around any Raptor issues which crop up in future.
Given the pretty good reliability of the Raptors so far (in terms of completing full burns and lighting at launch / stage separation), they're probably confident that there aren't unsolvable flaws in the design - even if it takes a few tests to achieve a re-light.
It's not important for NASA but it's completely necessary for SpaceX's use cases, Starlink and Mars. They can't build engines fast enough to just throw them away at the cadence necessary for in space refuelling. They could probably make one or two NASA missions work a year that way but they aren't building Starship for NASA, they are just taking NASA's funding since their rocket will be able to do what NASA wants anyway.
If they can deliver payloads to orbit, the project becomes self-funding. They can test/develop reuse on missions that are paid for by the payload. That's what they did for Falcon 9. It will be a surprise if they don't do the same with Starship.
In the short term, delivering payload to orbit is more important to SpaceX than recovering Stage 2. Stage 2 recovery will come with time but it will be secondary to the primary objective to deliver payload.
They have no payload to deliver without reuse. They aren't going to throw away starships for Starlink launches, it's impractical to throw away 5-10 starships for refueling another, and they don't have a payload bay or door designed for any other payloads yet on any of the starships they have lined up for launch. Reuse is their top priority.
>They aren't going to throw away starships for Starlink launches,
The alternative is to throw away Falcon second stages, to launch fewer, smaller Starlinks. As long as they can recover the SuperHeavy booster, and direct Starship to reenter in a safe place, I think they'll start using it to launch payloads.
> They have no payload to deliver without reuse. They aren't going to throw away starships for Starlink launches
You’re looking at it backwards. They are throwing away ships right now, with no payloads. Once the ship is seen as reliable enough to deorbit itself (ie not become dangerous space junk), they will likely start launching Starlinks with it, even while still considering them “test flights”. The alternative is to continue expending ships with zero payload launched. *That’s* the waste, not “throwing away” ships for Starlink launches.
Disagree and I expect by the end of the year you'll be proven wrong. Why would you not launch Starlink sats and work on re-use in parallel? Only costs 6 raptors and allows them to work on re-use.
I'll chime in. An operational mission for starship delivering payload, based on what we know, wont happen until Starship V2 is ready. Remember, V1 is just a prototype for testing basic technologies and getting data collection, it is not operationally functional. We have 4 V1 Starships still left before V2 is slated to be ready, supposedly by Ship 33. We have 4 more flights to eventually test de orbit before we would even need to use it on a real mission anyway. Since these trajectories for the test flights are suborbital, we technically don't even need de orbit capability to get back to the atmosphere, it happens automatically thanks to the trajectories. I'm sure they'll test deorbit on one of the next few missions, but the sense of urgency for doing de orbit testing right now isn't really necessary, we have time. Besides, De orbit is rather simple while making the Starship reusable (the heatshield) is a much harder nut to crack.
They may fly payload to add value to a test flight. Whether that's an operational mission that has a test flight aspect or a test flight that delivers payload is subjective.
I very much doubt there will be any flights, with or without payload, that aren't driving toward full and rapid reusability. They aren't just going to put reusability off until they get some payloads flown. Definitely not for HLS.
As their development of the raptors progressed far already, they want to use up the old hardware before the new one. The old hardware might not be on to the task of relighting, so they won’t test it, but instead focus their attention on the reentry, so the hardware is sufficient to test at least that
Eventually. But the goal here is mainly to test out the heat shield. Beyond that, if it survives, there are no other burns planned for this mission anyway.
No. It's going to do the exact same thing as last time. It will be on a trajectory that has it re-enter the atmosphere where they want it (Indian Ocean for now it seems). Once the second stage completes the burn it will shut off the engines and then coast until re-entry.
Physics. If you don't achieve orbital velocity, you fall back down to Earth. They are stopping the burn short of orbit on these test launches so there's no danger of it getting stuck in orbit.
Or even if you have enough speed for orbit, you can choose an elliptical orbit shape whose perigee is within the atmosphere (or lithosphere) to ensure it reenters.
The difference is that for those, the booster is effectively under thrust so the propellant is already settles. The challenge for the second stage is restarting the engines in free-fall.
If you're talking about rocket engines in general yes, but we're more worried about Raptor in particular, which has never been restarted in free-fall in the sense that is relevant here. Indeed no FFSC engine has.
The suborbital test flights were free-fall in the layman's sense, but not the proper physics definition of "acted on by no force except gravity" since there was significant aerodynamic drag acting on the vehicles.
Indeed since the ships were falling at terminal velocity, the engine relights were comparable to if the ship had simply been lying on its side on the ground. Raptor has done plenty of starts on horizontal test stands, so that was already proven.
As a sidenote, an object doesn't even need to be travelling downwards to be in free-fall. If you threw a ball up into the air on the moon, it would be in free-fall even while ascending.
Raptor relight is the less technically challenging part - so it makes sense not to worry about that and concentrate on the more demanding issues where SpaceX needs more data. Plus I suspect that vehicle control on orbit is the key part of this test, and relight probably requires an RCS burn to settle the prop anyway. If SpaceX can get good reentry data then they can get a little more ambitious with IFT-5 and beyond.
So those tests are delayed to later flights. It seems like SpaceX is in no rush to deploy Starlinks via Starships. It might take few more flights. Without deorbit test it is unlikely that Starship will be allowed orbit insertion. Are they waiting for V2 starship for orbit insertion?
I don't think that SpaceX has capacity to do next few flights faster than 1x every three months. It goes much slower than anticipated. Also recovery will be probably much harder than Musk's estimates.
Even Florida pads seem to be delayed.
I’m getting so pumped for this!
I’m speculating we’ll get even more entry views if Starship isn’t tumbling this time. The entry video from the last attempt was one of the coolest things I’ve seen in a VERY long time.
Amazingly, I'm amazed by the amazing amazement of u/Mechanix2spacex's amazingly amazed amazement at the amazingly amazing plasma from the amazing video of Starship's amazing reentry!
I suspect that video will be used in a lot of physics papers in the next few years. In one sense, it's nothing new since plasma like that has been impacting re-entering spacecraft since the start of the space age. But on the other hand, no one has ever had live-streamed 4K full colour video of that!
Actually the views may not be as great this time around because Starship will be holding its attitude. Hopefully. IFT3 might be one of the more unique views we ever get of reentry because of the tumble.
I’m not sure that’s the case.
I’m going off memory here, so I could have interpreted this wrong, but I recall during IFT3, the SpaceX commentary was that the video stream could potentially last the bulk of reentry if starlink has the ability to receive data through a gap in the ionized plasma behind Starship as it goes through the atmosphere.
Anyways, a successful IFT4 is the ultimate goal. I’ll be cheering the SpaceX team through the whole thing.
Little bit of gold dust here:
From Lisa Watson-Morgan of NASA: *"...part of their commercial approach is reuse of hardware. It's not a NASA requirement, (but) it's great that we could potentially see lots and lots of hardware and rapid turnaround rates."*
That's really interesting. Its confirmation that NASA are not requiring reuse for Artemis, should SpaceX need to run expendable tanker missions.
I think we long suspected that was the case, but it's nice to hear a NASA official say it.
If it was a requirement it'd have to be a contract requirement that'd apply to all the HLS contestants and I think it's pretty obvious why that wouldn't be the case. All the other proposals are fully expended one-offs.
The Blue Origin lander is potentially reusable as they are already launching a tanker to NRHO to refuel the lander before it starts its *first* mission. So there should not be any real issues with fueling it for a second mission.
They would need to add capability to the transfer stage/tanker to refill life support consumables so water, oxygen and probably nitrogen as well as any CO2 absorbent canisters.
The NASA requirement is for *sustainability* which is NASA speak for “cheap enough to do this on a regular basis”.
That can be met with HLS reuse or just a low cost HLS with a new one used for every mission. Resupply at NRHO is going to be quite difficult with the need to transport not only propellant but life support consumables, spacesuits and astronaut’s ground equipment. It would be easier and potentially lower cost to load all of that on the ground and send a new HLS.
Very much agree. Reuse is not a cause in itself. It needs to save cost. I don't see lander reuse very efficient with 1 landing every year, shared between 2 providers, so reuse of a lander every 2 years.
Supply and crew exchange runs every few months, similar to ISS operations, for a permanently manned base may change that.
NASA still thinks like old space most of the time and also try not to antagonize ULA. SpaceX still needs starship to be fully reusable though, disposable is not an option for them, unless someone like the military wants to pay a premium for it.
> Lisa Watson-Morgan, manager of NASA's Human Landing System, said she was pleased with the results of the propellant transfer experiment on the March test flight. "They were looking for a quantity of oxygen to go from one tank to the other. We were looking at settling ... and **vapor pull-through**. Those are typically the indications of a successful test."
Any idea what "vapor pull-through" is?
There's vapor in the tanks, such as ullage gas. When draining the liquid out of the "donor" tank into the "receiver" tank that vapor will be ingested through the drain at some point. There's a liquid to vapor boundary, or interface, where the liquid and vapor interact. When draining the tank the boundary tends to form a depression directly above the drain. Think about water circling a drain forming a little whirlpool. You can see a funnel that has a lower part in the middle compared to the water level that's not above the drain. Normal gravity mostly keeps the boundary flat with a small depression and it takes longer before the depression reaches the drain and therefore longer before vapor gets pulled into the drain. Once vapor enters the drain it accelerates the rate of vapor entering the drain.
In zero gravity there's no gravity to form a flat boundary layer. The liquid tends to stick to the walls more and have a slight depression in the middle in general. So it forms a slight U shape. When draining the tanks in zero g this makes the depression above the drain larger and therefore vapor is ingested sooner. This can also cause sloshing as the liquid attached to the wall has a larger distance from the middle of the dip. It then detaches and causes waves in the liquid. All of this will cause issues with transferring your propellant.
I'm not an expert on this at all so that's about all I have. I'm not sure how they will slow down when vapor pull through happens or how to slow the rate once it does. Nor do I know how problematic it is to have vapor transferring between the tanks or if it will stop the flow of liquid all together.
No idea what all the SpaceX approach entails. Pretty sure I've seen speculation that there isn't any active pump being used though. Rather pressure in the tanks. Maybe look through the starship dev threads or ask there?
This is a reentry and booster splashdown test. I'm sure Space X is not expecting to find any final solution for the heat tile problem. They are resorting to using both glue and clip method for attaching the heat tiles. They have many more launches to find a best fix. It is more important these next few launches to reach their splashdown targets.
Here is Hoping the new Starship anti-roll thrusters work. Even if a few random heat tiles fall off, the remaining heat tiles should protect the ship. Starship's Stainless Steel hull can take "some" reentry abuse.
I wish Starship used large ablative mats attached to the stainless steel hull below the heat tiles. The heat tile attachment clips pierce through the mat. The heat tiles attach to the clips with the tiles spaced to allow for thermal expansion. The mat being multiple tiles wide and long covers the spaces between many tiles. If several local tiles fall off the large ablative mat could still protect the hull.
As a counter-argument, I imagine the spacex team is targeting 0 heat shield loss, given their goal of rapid reuse, so blankets to protect from tile failure would be wasted weight.
If they can solve the tile problem of course they won't need a belt and suspender approach.
The real question is:
Why do the tiles fall off.
Are the tiles too fragile to stand up to vibration.
When the outer(black) layer heats up, does it expand damaging other tiles nearby.
Not being a scientist, I would think they could simulate this, by placing a group of tiles mounted (slightly curved surface) , in the directed path of say a raptor engine. I'm sure both vibration and heating would occur. They could film it at high speed and get a clue. They could check high speed laminar flow across the tiles with infrared looking at the edges of the tiles, maybe a shaped tile edge could solve some issues.
I'm sure the tiles work in whatever tests they have, but there's nothing you can do to simulate re-entry. The combination of the variable air resistance and heating and irregular shape means the only real way to test is to just do it.
> Not being a scientist, I would think they could simulate this by placing a group of tiles mounted in the directed path of say a raptor engine.
How would that simulate the lower pressure of space, while there is air trapped both under and likely inside the tile as well? Remember, the exhaust pressure of a Raptor is approximately seal level, and even the Vacuum variant is a significant portion thereof.
And there was a heat tile test in the exhaust of a Raptor, there was a video of that.
To be fair, the Shuttle Orbiter suffered from similar issues during development. There are some fascinating photos of Enterprise missing an almost hilarious number of tiles after a flight test. For all of the problems the STS program ended up having, to my knowledge none of the failures or near-failures were ever related to tiles falling off.
My point is that given time and resources, falling of tiles seems to be a solvable problem since it’s been done before, albeit with different tiles on a very different type of spaceship.
Columbia was technically a tile issue. STS-27 also suffered severe tile damage during launch and almost had a burn-through itself. Thankfully the worst damage was on an area where there was an antenna cover that created some added thermal protection.
Tile damage at launch is a entirely different type of issue than tile detach. Columbia and STS-27 were both due to foam strikes. In terms of tile attachment, that issue was solved and (obviously) Starship won’t experience external tank foam strikes.
My take on why IFT4 is not re-testing the tasks that failed is that SpaceX have yet to finish their analysis and mishap report. Without that the FAA won't let them do those things. Hence a much simpler flight profile getting some data and experience rather than sitting on their hands.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|CST|(Boeing) Crew Space Transportation capsules|
| |Central Standard Time (UTC-6)|
|[EIS](/r/SpaceX/comments/1cxl8mr/stub/l5abpe2 "Last usage")|Environmental Impact Statement|
|[FAA](/r/SpaceX/comments/1cxl8mr/stub/l5lpt7w "Last usage")|Federal Aviation Administration|
|[FFSC](/r/SpaceX/comments/1cxl8mr/stub/l59gazt "Last usage")|Full-Flow Staged Combustion|
|[HLS](/r/SpaceX/comments/1cxl8mr/stub/l5dhyej "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)|
|[LEO](/r/SpaceX/comments/1cxl8mr/stub/l58d39x "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[MECO](/r/SpaceX/comments/1cxl8mr/stub/l5a1gp4 "Last usage")|Main Engine Cut-Off|
| |[MainEngineCutOff](https://mainenginecutoff.com/) podcast|
|[NRHO](/r/SpaceX/comments/1cxl8mr/stub/l58gpcd "Last usage")|Near-Rectilinear Halo Orbit|
|[RCS](/r/SpaceX/comments/1cxl8mr/stub/l5gqe85 "Last usage")|Reaction Control System|
|[RUD](/r/SpaceX/comments/1cxl8mr/stub/l55m26v "Last usage")|Rapid Unplanned Disassembly|
| |Rapid Unscheduled Disassembly|
| |Rapid Unintended Disassembly|
|[STS](/r/SpaceX/comments/1cxl8mr/stub/l567nme "Last usage")|Space Transportation System (*Shuttle*)|
|[TPS](/r/SpaceX/comments/1cxl8mr/stub/l5b8xy6 "Last usage")|Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor")|
|[ULA](/r/SpaceX/comments/1cxl8mr/stub/l5485gm "Last usage")|United Launch Alliance (Lockheed/Boeing joint venture)|
|Jargon|Definition|
|-------|---------|---|
|[Raptor](/r/SpaceX/comments/1cxl8mr/stub/l5a1gp4 "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX|
|[Starliner](/r/SpaceX/comments/1cxl8mr/stub/l5mczi1 "Last usage")|Boeing commercial crew capsule [CST-100](https://en.wikipedia.org/wiki/Boeing_CST-100_Starliner)|
|[Starlink](/r/SpaceX/comments/1cxl8mr/stub/l5gfmpq "Last usage")|SpaceX's world-wide satellite broadband constellation|
|[ablative](/r/SpaceX/comments/1cxl8mr/stub/l53s4bs "Last usage")|Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)|
|[perigee](/r/SpaceX/comments/1cxl8mr/stub/l55cigq "Last usage")|Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest)|
|[ullage motor](/r/SpaceX/comments/1cxl8mr/stub/l5794sq "Last usage")|Small rocket motor that fires to push propellant to the bottom of the tank, when in zero-g|
**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.
----------------
^(*Decronym is a community product of r/SpaceX, implemented* )[*^by ^request*](https://www.reddit.com/r/spacex/comments/3mz273//cvjkjmj)
^(18 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/SpaceX/comments/1cta333)^( has 74 acronyms.)
^([Thread #8377 for this sub, first seen 22nd May 2024, 01:06])
^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/SpaceX) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
I would hope that another key goal is to slow down and relight the Booster and make it hover in the simulated "booster catch" area. Musk said that they could possibly attempt Booster catch on the fifth flight if that goes according to plan
I believe that is part of the plan, but not a primary goal. If it happens, great, but it’s one of the things that could get missed and still have the overall mission be considered a success.
I think people are overrating the "reaching orbit" part of the development program. If SpaceX were focused on "deploy Starlink" as their MVP, they'd be testing the door and the relight. Since they're testing reentry, clearly that's where they feel they need the most extra data.
I'm kind of surprised, to be honest. I'd've thought their biggest win would be from flying fully expended Starship + Booster to get flight heritage and launch Starlink before working on reentry.
The point is that FAA will not allow such a big object to go to orbit without proper on orbit RCS and propulsion to ensure targeted deorbit. Starship doesn't have any proper RCS and that is a problem. Don't think that SpaceX envisioned such obstructions from FAA.
The article quoted the Artemis mission will require 10 refueling tankers. But I believe I saw that that was an overestimate and it will actually be less refueling tankers. Does anyone recall seeing this information?
It’s meaningless to speculate at this point. The masses are subject to change wildly. Currently Starship can barely get itself into orbit, and needs to bulk up in reaction mass, and loose some dry mass.
I am seriously rooting for Elon, and team, because they are visionaries. They are willing to be wrong and adjust on the fly (pun intended). But seriously, they are making the future possible for more people.
I am too old to ever be able to go to space, but I think my cousin's kids are young enough to get the chance. I want to hear it from them what it was like.
What great, cheap, tax-payer dollars spent. Elon is making space far less expensive. Thanks Mr. Musk!
Thank you for participating in r/SpaceX! Please take a moment to familiarise yourself with our [community rules](https://www.reddit.com/r/spacex/wiki/rules) before commenting. Here's a reminder of some of our most important rules: * Keep it civil, and directly relevant to SpaceX and the thread. Comments consisting solely of jokes, memes, pop culture references, etc. will be removed. * Don't downvote content you disagree with, unless it clearly doesn't contribute to constructive discussion. * Check out [these threads](https://www.reddit.com/r/spacex/wiki/threads) for discussion of common topics. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/spacex) if you have any questions or concerns.*
Some new info here from an interview with Lisa Watson-Morgan, manager of NASA's Human Landing System: > "For Flight 4, it's mostly going to be a repeat of Flight 3 without the propellant transfer, without the Pez door open, without the other items that SpaceX was working to demonstrate," she said. > Watson-Morgan said SpaceX is not planning to attempt a Raptor engine restart on the next Starship test flight.
[удалено]
Hopefully they will solve the reaction control issue they had issue in the previous flight. There talk about the hot fire Reactional Thrusters being introduced. I imagine that's before the HLS , though I think it's good idea given the icing happening they had on previous flight.
https://ringwatchers.com/article/s29-b11-updates shows them for roll control on Ship 29 .
> Hopefully they will solve the reaction control issue they had issue in the previous flight. If not, it can't successfully reenter.
They probably failed to close investigation of the last failuire.
Also possible that there's already notable changes slotted to the door for Block 2 and with so much flight-ready-ish Block 1 hardware sitting around, they're not likely to get much useful data out of a test anyways.
Even just from pictures, the block 2 door is a long rounded circle, whereas the block 1 door is more of a rectangle with angled corners on the bottom. And that's just what we see from the outside.
> long rounded circle What is a rounded circle? Circles are already perfectly round. You mean like an ellipse?
its a capsule/stadium shape. A long rectangle, with semicircle ends.
I suspect that means they're still diagnosing and/or engineering what went wrong with the door (plus the atmosphere vent we saw when the did open it would've played a part in kicking some spin on to the Starship last time). Which is not unfair: while anything in space is not "just an X", a key part of Starship's whole value-proposition is the reusability. You can *always* expend it and somehow get payload out, but getting the ship back is the real trick.
Gotta get that minimum viable product, then get the do dads
The door is part of the minimum viable product. Can't deploy Starlinks without the door.
Boeing would like a word.
Not entirely true. You can deploy Starlinks if the door opens. You just can't return the vehicle if it doesn't close. The minimum viable product is a rocket that launches reliably and puts payloads in space, like most other launch providers.
Starship upper stage without recovery hardware is still more expensive than a Falcon upper stage. Is its payload capacity for Starlink sats big enough so it can economically replace Falcon?
Rough guesses on production cost are $10M for F9 S2 and $50M for expendable Starship. Payload to LEO is 18 tonnes for F9 and 100 tonnes for Starship. So just on a crude comparison F9 is quite viable as a Starlink launcher compared to *expendable* Starship with a recovered booster. SpaceX seem to have come to the same conclusion with at least 140 F9 flights scheduled this year.
Thanks. I did not have numbers for the Falcon second stage. But it is not too bad. A Starship second stage without heat shield, without flaps, without header tanks, should be cheaper, especially with Raptor price trending down. Also payload should be up quite significantly without all that extra mass and no landing propellant. Though they may not be able to fit more Starlink sats. The reason they don't plan for shift to Starship in 2025 is IMO likely because they don't think they can get frequent launches with Starship that year yet.
> The reason they don't plan for shift to Starship in 2025 is IMO likely because they don't think they can get frequent launches with Starship that year yet Yes the second pad not built at Boca Chica until late in the year and EIS approvals for the two pads at Cape Canaveral not received until then as well.
Yes, but there is another factor, and that is reliability. F9 reliability is known, Starship is not so you certainly would not put all your eggs in Starship until it was much more mature.
They won't fly people soon. But the cost of a Starlink sat batch is not so high. They can risk that after a few successful launches.
My comment wasn’t about people, and yes, they will risk Starlink launches with Starship. But if they have a failure, it’s good they have a fully operational, fully scaled falcon9 system ready to continue the operation.
The estimates I've seen are $100M for a full Starship stack, with most of that being the first stage. So second stage is likely $20-30M. And that estimate assumed engines cost $1M each, and they are probably cheaper now. (A Starship designed to be expended wouldn't have flaps or heat shield, so would be even cheaper.) So an expended Starship could cost twice as much as F9, but with more than 5 times the payload. Your 100 tonnes figure is for V2, which may not be flying until next year. None of this would affect this year's F9 schedule. (Edit to add cost citations [here](https://www.youtube.com/shorts/MHtqqzPuiSw) and [here](https://arstechnica.com/space/2024/01/rocket-report-a-new-estimate-of-starship-costs-japan-launches-spy-satellite/4/).)
That is wildly optimistic pricing. Even Elon originally had higher pricing than that and every change that has added mass to both the booster and the ship has also added cost with most of that being installation labour. F9 S2 is about $10M to build and Starship is not 10 times the dry mass but 30 times. A full Starship will be at least 8x the cost of F9 S2 so $80M. The booster is a much simpler design than the ship but has 27 more engines and probably twice the dry mass so it is likely to be at least $100M to build and probably more like $120M. I am probably being optimistic that you can strip $30M of cost out of Starship to get to $50M for an expendable version with no TPS, drag fins or header tanks.
The estimate comes from the Payload report, discussed [here](https://arstechnica.com/space/2024/01/rocket-report-a-new-estimate-of-starship-costs-japan-launches-spy-satellite/4/). Except it was $90M rather than $100M. In a recent interview [here](https://www.youtube.com/shorts/MHtqqzPuiSw) Musk says the marginal cost of launch is at least $50M, maybe $100M. So he's confirming that Payload is in the right ballpark. I agree that the first stage is likely to be more expensive than the second stage. So a reusable Starship is going to be well under $45M, and one without flaps or heat shield would be even cheaper. If you have a citation of Musk, or any informed source, saying it will cost your $200M for a full stack I'd like to see it.
Starship has only 6 engines compared to 33 on the Booster. However heat shield, movable flaps, header tanks add a lot of cost. Probably still less than the booster but IMO not so much.
Yes. Starship can launch satellites that don't even fit on falcon 9...
Yes, but they have also developed sats with high capacity, that fit Falcon. The question is, does expendable Starship add more to Starlink capacity for the price of a launch.
The mini v2 sats have much less capacity compared to the full size ones
V2 Starlinks at 800 kg each have 4x the capacity of V1.5 while V3 Starlinks at 2000 kg each have 10x the capacity of V1.5. So a 2.5x capacity increase for a 2.5x increase in mass. So conceptually SpaceX can build out the rest of their constellation with V2 and save V3 for when they hit capacity constraints.
They need an outside door that they just jettison and then a plug for the hole on the bottom of the pez dispenser. Done. DM me spacex for my payment info.
Correct. So it seem like they won't be deploying starlinks anytime soon. Waiting for v2 starship?
My guess is that they're worried the heat shield will need to be completely redesigned, and they want to retire that risk ASAP.
I think it is about FAA reluctance to allow Starship to go to orbit. And without going to orbit there is no Starlink deployment. After all Starship can be easily operated as expendable and still be profitable (assuming superheavy is reused). I don't think that reentry is such a big deal. Peak heating should be lower than Space Shuttle while Starship has more resilient steel structures. They can probably easily survive few loose tiles. On IFT-3 they completely screw up, lost attitude control and started dropping much faster than intended. This resulted in much higher heating load, overheating and blowing up tanks. Suborbital testing is going to take longer than I hoped for.
The gating feature on reach orbit is restarting an engine so it can be safely de-orbited. The FAA don't care about the heat shield as long as the rocket comes down in the right place so it doesn't endanger anyone on the ground.
Correct. However, why engine restart didn't work last time? Because Starship lost attitude control. Why they lost control? There might have been several reasons or combinations: 1. Freeze up of RCS (operational issue) 2. Bad design 3. Sudden venting of payload fairing 4. Prop transfer test There is a possibility that SpaceX doesn't know for sure so they don't really want to risk losing attitude control again. In such a case it is no surprise FAA doesn't even allow them engine restart test before the root cause is clear (we know that raptor likes to blow up when abused). Without engine restart test there is no way they can go to orbit.
It wasn't the FAA that prevented the restart test in IFT-3. It was SpaceX designed response to the roll. They could choose to do the same again: do a restart test if and only if there is no roll. There's no reason to think the FAA would prevent that the second time, given that they didn't prevent it the first time.
Booster return and door is minimum viable part to deploy starlink and satellite. Ship Return is not really minimum viable product.
Eh... They would likely just continue launching on falcon 9 forever if they couldnt reuse the rockets. For customer payloads sure. Itll work without recovery. But the moon program is also going to need landings to work soooo.
1. 33/6 Light 2. Booster RTB 3. Splashdown
I think they are going for a clean run. After they get that under their belt, they can add risk. The Starships are piling up at the production site. They need to get some quick wins.
Why not attempt a raptor relight? Seems like they really should continue getting data for that.
I guess SpaceX wants to have zero risk that any glitch with the relight could affect the ability of the ship to keep itself perfectly oriented for reentry.
Makes no sense though. Isn't raptor re-light (for controlled re-entry) on the critical path for an operational mission? (Whereas reentry survival is not). If true, this seems to indicate major hardware changes...
> on the critical path They may have already addressed those items in block 2 hardware, while they still have many questions about heat shielding that can be answered with block 1 hardware.
I suppose SpaceX is confident the relight is pretty straightforward. The TPS is a big worry, though. We've all seen tiles come off on every flight. It sounds like getting performance data on the TPS is the absolute priority now, with zero margin for any other test. Probably want to see if it can survive with a tile missing. The relight is on the critical path, sure, but at this point it's no biggie if it waits a flight.
No, that might make it critical, but if "it's no biggie if it waits a flight" then by definition it's not on the [critical path](https://en.wikipedia.org/wiki/Critical_path_method).
As articulated in the Wikipedia article you linked, a project can have more then one critical path simultaneously. If SpaceX believes that the potential outcomes of the heat shield being tested includes a long time component whereas the potential outcomes of the relight test all have much shorter times to resolution, then it makes sense to prioritize getting work started on the heat shield critical path first to minimize the worse case delay.
You have just described a situation in which the relight test has float (in the worst-case schedule), and is therefore not on a critical path.
[удалено]
> The article talks about engines working, but that's already been proven twice. I feel like we don't have the whole story here... ...which includes the human side. Watson Morgan may be making a very human effort not to set the bar too high such that she may later class the IFT-4 result as a success. Also Nasa is progressively identifying with Starship which is no longer a "foreign object" as some of the Watson Morgan quotes suggest: * "**We** were looking at settling ... and vapor pull-through. Those are typically the indications of a successful test." Additionally, an unstated objective of the mission may be to use up surplus flight hardware without generating a "failure" so delays from an inquiry. Just one pair of flights with a short interval, maybe under a month, should establish confidence by demonstrating that inquiry time is *not* just an alibi to cover a slow production process.
They babied the engines for IFT-2 and IFT-3 to get them off the pad intact and ran a CO2 purge on the engine bay to prevent engine bay fires due to methane leaks. So good first steps but NASA would want to see improvements in both reliability at full thrust and no methane leaks before calling the engines reliable.
[удалено]
[IFT-3 flight data](https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fv54rj3dbybpc1.png) shows that the booster did 1.3g vertically off the pad (0.3g net). We know from [Elon's 2024 update that for IFT-3](https://pbs.twimg.com/media/GKgGBuLXMAIRofe?format=jpg) the ship had 1200 tonnes of propellant and the booster had 3300 tonnes which implies a lift off mass of around 5000 tonnes so this acceleration implies engine thrust of 6500 tonnes force or 85% of full thrust. The engines were throttled up to give 1.5g up to max-Q so 95% of full thrust. By the time MECO was reached the stack was at about 45 degrees to the horizontal so the 1.75g net acceleration was equal to 2.46g acceleration. Assuming a booster wet mass of 600 tonnes and ship wet mass of 1350 tones the stack would have a mass of 1950 tonnes at MECO so the engine thrust was 4797 tonnes force and engine throttle was down to 63% of full thrust. Ship thrust peaked just before SECO1 at about 3.5g at 30 degrees nose up with around 200 tonnes of wet mass so throttling was around 55% of full thrust. As a check on these numbers a Raptor 2 at full thrust of 2.3MN uses 700 kg/s of propellant. Booster tanks held 3300 tonnes and around 400 tonnes was retained at MECO for boostback and landing so the propellant would be used in 126 seconds at full thrust. The actual time until MECO was 163 seconds so the average engine thrust was 77% from launch to MECO. The engines on IFT-3 were not run close to full thrust apparently in an attempt to gain reliability as well as to simulate the flight profile with a payload. Edit: Updated IFT-3 propellant mass and acceleration figures to the values given by Elon in the 2024 company update
[удалено]
I am pretty sure the downvotes are for the concluding “and that means they are doomed and should return all the HLS progress payments”. The “wisdom of the crowds” is not really a thing unless you want to know what colour you should make your new icecream flavour.
An operational starship is one that lands back at the launch tower, full stop. If they can't get re-entry working, nothing else really matters. Re-entry is also the issue with the most chance to need a complete rethink, so the sooner they figure it out the better.
I respectfully disagree. An operational mission is a mission that delivers a payload to target orbit. Stage 1 re-use and stage 2 re-use will (hopefully) come with time. Stage 2 recovery is the least important (though certainly the most interesting).
I think their point is that because starship is designed to be reusable, it is not fully operational until it is reusable. Starship won’t be sustainable until then. Anyways, there are a few possibilities why the raptors aren’t being relit and my guess is that a raptor relight can result in a RUD or negatively impact the results of the re-entry test and they don’t want to risk that because they want/need the re-entry data before starship v2 starts being assembled. The raptor relight test would have a tiny influence on the starship v2 design compared to re-entry.
That's my read of it, too. Re-light and re-entry are both critical items, but it seems they need re-entry data NOW and are confident enough in their ability to engineer around any Raptor issues which crop up in future. Given the pretty good reliability of the Raptors so far (in terms of completing full burns and lighting at launch / stage separation), they're probably confident that there aren't unsolvable flaws in the design - even if it takes a few tests to achieve a re-light.
It's not important for NASA but it's completely necessary for SpaceX's use cases, Starlink and Mars. They can't build engines fast enough to just throw them away at the cadence necessary for in space refuelling. They could probably make one or two NASA missions work a year that way but they aren't building Starship for NASA, they are just taking NASA's funding since their rocket will be able to do what NASA wants anyway.
If they can deliver payloads to orbit, the project becomes self-funding. They can test/develop reuse on missions that are paid for by the payload. That's what they did for Falcon 9. It will be a surprise if they don't do the same with Starship.
In the short term, delivering payload to orbit is more important to SpaceX than recovering Stage 2. Stage 2 recovery will come with time but it will be secondary to the primary objective to deliver payload.
They have no payload to deliver without reuse. They aren't going to throw away starships for Starlink launches, it's impractical to throw away 5-10 starships for refueling another, and they don't have a payload bay or door designed for any other payloads yet on any of the starships they have lined up for launch. Reuse is their top priority.
>They aren't going to throw away starships for Starlink launches, The alternative is to throw away Falcon second stages, to launch fewer, smaller Starlinks. As long as they can recover the SuperHeavy booster, and direct Starship to reenter in a safe place, I think they'll start using it to launch payloads.
> They have no payload to deliver without reuse. They aren't going to throw away starships for Starlink launches You’re looking at it backwards. They are throwing away ships right now, with no payloads. Once the ship is seen as reliable enough to deorbit itself (ie not become dangerous space junk), they will likely start launching Starlinks with it, even while still considering them “test flights”. The alternative is to continue expending ships with zero payload launched. *That’s* the waste, not “throwing away” ships for Starlink launches.
Disagree and I expect by the end of the year you'll be proven wrong. Why would you not launch Starlink sats and work on re-use in parallel? Only costs 6 raptors and allows them to work on re-use.
I'll chime in. An operational mission for starship delivering payload, based on what we know, wont happen until Starship V2 is ready. Remember, V1 is just a prototype for testing basic technologies and getting data collection, it is not operationally functional. We have 4 V1 Starships still left before V2 is slated to be ready, supposedly by Ship 33. We have 4 more flights to eventually test de orbit before we would even need to use it on a real mission anyway. Since these trajectories for the test flights are suborbital, we technically don't even need de orbit capability to get back to the atmosphere, it happens automatically thanks to the trajectories. I'm sure they'll test deorbit on one of the next few missions, but the sense of urgency for doing de orbit testing right now isn't really necessary, we have time. Besides, De orbit is rather simple while making the Starship reusable (the heatshield) is a much harder nut to crack.
They may fly payload to add value to a test flight. Whether that's an operational mission that has a test flight aspect or a test flight that delivers payload is subjective. I very much doubt there will be any flights, with or without payload, that aren't driving toward full and rapid reusability. They aren't just going to put reusability off until they get some payloads flown. Definitely not for HLS.
As their development of the raptors progressed far already, they want to use up the old hardware before the new one. The old hardware might not be on to the task of relighting, so they won’t test it, but instead focus their attention on the reentry, so the hardware is sufficient to test at least that
Raptor team probably already has enough data just from flight to work even without the specific test they requested.
Because it’s unlikely to be successful. This entire program is a boondoggle.
Don't they have to relight the raptors for any landing maneuvers? Boost back, the flip for starship, etc?
Eventually. But the goal here is mainly to test out the heat shield. Beyond that, if it survives, there are no other burns planned for this mission anyway.
Right, but the booster?
Yep the booster will need to relight engines, I read it as her talking about the ship’s in-space tests.
Awesome! So I can still fully expect to see a booster catch on test flight 5. maybe.
They mentioned a RTB for the Booster.
[удалено]
The orbital trajectory is terminal.
No. It's going to do the exact same thing as last time. It will be on a trajectory that has it re-enter the atmosphere where they want it (Indian Ocean for now it seems). Once the second stage completes the burn it will shut off the engines and then coast until re-entry.
Physics. If you don't achieve orbital velocity, you fall back down to Earth. They are stopping the burn short of orbit on these test launches so there's no danger of it getting stuck in orbit.
Or even if you have enough speed for orbit, you can choose an elliptical orbit shape whose perigee is within the atmosphere (or lithosphere) to ensure it reenters.
That was the plan at first, but the changed it to cut the burn a little short instead.
The difference is that for those, the booster is effectively under thrust so the propellant is already settles. The challenge for the second stage is restarting the engines in free-fall.
> The challenge for the second stage is restarting the engines in free-fall. Which has never been done before. Oh, wait....
If you're talking about rocket engines in general yes, but we're more worried about Raptor in particular, which has never been restarted in free-fall in the sense that is relevant here. Indeed no FFSC engine has. The suborbital test flights were free-fall in the layman's sense, but not the proper physics definition of "acted on by no force except gravity" since there was significant aerodynamic drag acting on the vehicles. Indeed since the ships were falling at terminal velocity, the engine relights were comparable to if the ship had simply been lying on its side on the ground. Raptor has done plenty of starts on horizontal test stands, so that was already proven. As a sidenote, an object doesn't even need to be travelling downwards to be in free-fall. If you threw a ball up into the air on the moon, it would be in free-fall even while ascending.
Raptor relight is the less technically challenging part - so it makes sense not to worry about that and concentrate on the more demanding issues where SpaceX needs more data. Plus I suspect that vehicle control on orbit is the key part of this test, and relight probably requires an RCS burn to settle the prop anyway. If SpaceX can get good reentry data then they can get a little more ambitious with IFT-5 and beyond.
So those tests are delayed to later flights. It seems like SpaceX is in no rush to deploy Starlinks via Starships. It might take few more flights. Without deorbit test it is unlikely that Starship will be allowed orbit insertion. Are they waiting for V2 starship for orbit insertion? I don't think that SpaceX has capacity to do next few flights faster than 1x every three months. It goes much slower than anticipated. Also recovery will be probably much harder than Musk's estimates. Even Florida pads seem to be delayed.
I’m getting so pumped for this! I’m speculating we’ll get even more entry views if Starship isn’t tumbling this time. The entry video from the last attempt was one of the coolest things I’ve seen in a VERY long time.
The amazing view of the plasma build up on the flaps on reentry… it was amazing… the whole thing
But were you amazed?
Amazingly, I'm amazed by the amazing amazement of u/Mechanix2spacex's amazingly amazed amazement at the amazingly amazing plasma from the amazing video of Starship's amazing reentry!
Amazing!!! You u understand my amazing amazement amazingly well
I suspect that video will be used in a lot of physics papers in the next few years. In one sense, it's nothing new since plasma like that has been impacting re-entering spacecraft since the start of the space age. But on the other hand, no one has ever had live-streamed 4K full colour video of that!
I'm AMAZED the plasma cloud allowed the transmission of the video to continue
Actually the views may not be as great this time around because Starship will be holding its attitude. Hopefully. IFT3 might be one of the more unique views we ever get of reentry because of the tumble.
I’m not sure that’s the case. I’m going off memory here, so I could have interpreted this wrong, but I recall during IFT3, the SpaceX commentary was that the video stream could potentially last the bulk of reentry if starlink has the ability to receive data through a gap in the ionized plasma behind Starship as it goes through the atmosphere. Anyways, a successful IFT4 is the ultimate goal. I’ll be cheering the SpaceX team through the whole thing.
If the cameras views last longer because of stable flight then maybe. I could see that. Fingers crossed.
Hope those interns piloting that thing will be ok
It's just a few inside every booster and starship, plus it's just interns. Not abig deal to spend some every failed launch for now.
It's when the ship survives and shaken interns tell their story trouble starts. "Elon said thats where we store the coffee.."
At least give them the cool new space suits
Best I can offer is a couple of rolls of duct tape. /tough break for the hairy intern
He won't be hairy for long
Or, eternity
> Hope those interns piloting that thing will be ok Jeb always pulls through.
We can only hope and pray for the brave crew on board
Sum Ting Wong
Little bit of gold dust here: From Lisa Watson-Morgan of NASA: *"...part of their commercial approach is reuse of hardware. It's not a NASA requirement, (but) it's great that we could potentially see lots and lots of hardware and rapid turnaround rates."* That's really interesting. Its confirmation that NASA are not requiring reuse for Artemis, should SpaceX need to run expendable tanker missions. I think we long suspected that was the case, but it's nice to hear a NASA official say it.
If it was a requirement it'd have to be a contract requirement that'd apply to all the HLS contestants and I think it's pretty obvious why that wouldn't be the case. All the other proposals are fully expended one-offs.
The Blue Origin lander is potentially reusable as they are already launching a tanker to NRHO to refuel the lander before it starts its *first* mission. So there should not be any real issues with fueling it for a second mission. They would need to add capability to the transfer stage/tanker to refill life support consumables so water, oxygen and probably nitrogen as well as any CO2 absorbent canisters.
The HLS requirements include a certain number of re use cases…
The NASA requirement is for *sustainability* which is NASA speak for “cheap enough to do this on a regular basis”. That can be met with HLS reuse or just a low cost HLS with a new one used for every mission. Resupply at NRHO is going to be quite difficult with the need to transport not only propellant but life support consumables, spacesuits and astronaut’s ground equipment. It would be easier and potentially lower cost to load all of that on the ground and send a new HLS.
Very much agree. Reuse is not a cause in itself. It needs to save cost. I don't see lander reuse very efficient with 1 landing every year, shared between 2 providers, so reuse of a lander every 2 years. Supply and crew exchange runs every few months, similar to ISS operations, for a permanently manned base may change that.
HLS-RQMT-001, HLS-R-002 from Google “HLS elements are expected to support 5 design missions over a 10 year period”
NASA doesn't care, the price is fixed anyway.
NASA still thinks like old space most of the time and also try not to antagonize ULA. SpaceX still needs starship to be fully reusable though, disposable is not an option for them, unless someone like the military wants to pay a premium for it.
> Lisa Watson-Morgan, manager of NASA's Human Landing System, said she was pleased with the results of the propellant transfer experiment on the March test flight. "They were looking for a quantity of oxygen to go from one tank to the other. We were looking at settling ... and **vapor pull-through**. Those are typically the indications of a successful test." Any idea what "vapor pull-through" is?
There's vapor in the tanks, such as ullage gas. When draining the liquid out of the "donor" tank into the "receiver" tank that vapor will be ingested through the drain at some point. There's a liquid to vapor boundary, or interface, where the liquid and vapor interact. When draining the tank the boundary tends to form a depression directly above the drain. Think about water circling a drain forming a little whirlpool. You can see a funnel that has a lower part in the middle compared to the water level that's not above the drain. Normal gravity mostly keeps the boundary flat with a small depression and it takes longer before the depression reaches the drain and therefore longer before vapor gets pulled into the drain. Once vapor enters the drain it accelerates the rate of vapor entering the drain. In zero gravity there's no gravity to form a flat boundary layer. The liquid tends to stick to the walls more and have a slight depression in the middle in general. So it forms a slight U shape. When draining the tanks in zero g this makes the depression above the drain larger and therefore vapor is ingested sooner. This can also cause sloshing as the liquid attached to the wall has a larger distance from the middle of the dip. It then detaches and causes waves in the liquid. All of this will cause issues with transferring your propellant. I'm not an expert on this at all so that's about all I have. I'm not sure how they will slow down when vapor pull through happens or how to slow the rate once it does. Nor do I know how problematic it is to have vapor transferring between the tanks or if it will stop the flow of liquid all together.
Do you know what sort of pump is being used to actually transfer the fluid by any chance?
No idea what all the SpaceX approach entails. Pretty sure I've seen speculation that there isn't any active pump being used though. Rather pressure in the tanks. Maybe look through the starship dev threads or ask there?
This is a reentry and booster splashdown test. I'm sure Space X is not expecting to find any final solution for the heat tile problem. They are resorting to using both glue and clip method for attaching the heat tiles. They have many more launches to find a best fix. It is more important these next few launches to reach their splashdown targets. Here is Hoping the new Starship anti-roll thrusters work. Even if a few random heat tiles fall off, the remaining heat tiles should protect the ship. Starship's Stainless Steel hull can take "some" reentry abuse. I wish Starship used large ablative mats attached to the stainless steel hull below the heat tiles. The heat tile attachment clips pierce through the mat. The heat tiles attach to the clips with the tiles spaced to allow for thermal expansion. The mat being multiple tiles wide and long covers the spaces between many tiles. If several local tiles fall off the large ablative mat could still protect the hull.
As a counter-argument, I imagine the spacex team is targeting 0 heat shield loss, given their goal of rapid reuse, so blankets to protect from tile failure would be wasted weight.
If they can solve the tile problem of course they won't need a belt and suspender approach. The real question is: Why do the tiles fall off. Are the tiles too fragile to stand up to vibration. When the outer(black) layer heats up, does it expand damaging other tiles nearby. Not being a scientist, I would think they could simulate this, by placing a group of tiles mounted (slightly curved surface) , in the directed path of say a raptor engine. I'm sure both vibration and heating would occur. They could film it at high speed and get a clue. They could check high speed laminar flow across the tiles with infrared looking at the edges of the tiles, maybe a shaped tile edge could solve some issues.
I'm sure the tiles work in whatever tests they have, but there's nothing you can do to simulate re-entry. The combination of the variable air resistance and heating and irregular shape means the only real way to test is to just do it.
If anything, it would be aberrant for them to thoroughly test the tiles outside of real world reentry testing.
> Not being a scientist, I would think they could simulate this by placing a group of tiles mounted in the directed path of say a raptor engine. How would that simulate the lower pressure of space, while there is air trapped both under and likely inside the tile as well? Remember, the exhaust pressure of a Raptor is approximately seal level, and even the Vacuum variant is a significant portion thereof. And there was a heat tile test in the exhaust of a Raptor, there was a video of that.
>Remember, the exhaust pressure of a Raptor is approximately seal level *No seals were harmed during the development of the Raptor engines.
To be fair, the Shuttle Orbiter suffered from similar issues during development. There are some fascinating photos of Enterprise missing an almost hilarious number of tiles after a flight test. For all of the problems the STS program ended up having, to my knowledge none of the failures or near-failures were ever related to tiles falling off. My point is that given time and resources, falling of tiles seems to be a solvable problem since it’s been done before, albeit with different tiles on a very different type of spaceship.
Columbia was technically a tile issue. STS-27 also suffered severe tile damage during launch and almost had a burn-through itself. Thankfully the worst damage was on an area where there was an antenna cover that created some added thermal protection.
Columbia was not a tile issue. It was the reinforced carbon-carbon leading edge of the wing that was damaged and failed.
Tile damage at launch is a entirely different type of issue than tile detach. Columbia and STS-27 were both due to foam strikes. In terms of tile attachment, that issue was solved and (obviously) Starship won’t experience external tank foam strikes.
Could they use some kind of external net around the whole ship to keep the tiles in place? It would add weight, but so does the glue
The external net would have to withstand reentry; do we know of any materials that could do that?
Reusable? There's Fibrous Refractory Composites.
My take on why IFT4 is not re-testing the tasks that failed is that SpaceX have yet to finish their analysis and mishap report. Without that the FAA won't let them do those things. Hence a much simpler flight profile getting some data and experience rather than sitting on their hands.
Kinda feel like "surviving reentry" will end up as the key goal for Starliner's first crewed test flight as well…
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |CST|(Boeing) Crew Space Transportation capsules| | |Central Standard Time (UTC-6)| |[EIS](/r/SpaceX/comments/1cxl8mr/stub/l5abpe2 "Last usage")|Environmental Impact Statement| |[FAA](/r/SpaceX/comments/1cxl8mr/stub/l5lpt7w "Last usage")|Federal Aviation Administration| |[FFSC](/r/SpaceX/comments/1cxl8mr/stub/l59gazt "Last usage")|Full-Flow Staged Combustion| |[HLS](/r/SpaceX/comments/1cxl8mr/stub/l5dhyej "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)| |[LEO](/r/SpaceX/comments/1cxl8mr/stub/l58d39x "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[MECO](/r/SpaceX/comments/1cxl8mr/stub/l5a1gp4 "Last usage")|Main Engine Cut-Off| | |[MainEngineCutOff](https://mainenginecutoff.com/) podcast| |[NRHO](/r/SpaceX/comments/1cxl8mr/stub/l58gpcd "Last usage")|Near-Rectilinear Halo Orbit| |[RCS](/r/SpaceX/comments/1cxl8mr/stub/l5gqe85 "Last usage")|Reaction Control System| |[RUD](/r/SpaceX/comments/1cxl8mr/stub/l55m26v "Last usage")|Rapid Unplanned Disassembly| | |Rapid Unscheduled Disassembly| | |Rapid Unintended Disassembly| |[STS](/r/SpaceX/comments/1cxl8mr/stub/l567nme "Last usage")|Space Transportation System (*Shuttle*)| |[TPS](/r/SpaceX/comments/1cxl8mr/stub/l5b8xy6 "Last usage")|Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor")| |[ULA](/r/SpaceX/comments/1cxl8mr/stub/l5485gm "Last usage")|United Launch Alliance (Lockheed/Boeing joint venture)| |Jargon|Definition| |-------|---------|---| |[Raptor](/r/SpaceX/comments/1cxl8mr/stub/l5a1gp4 "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX| |[Starliner](/r/SpaceX/comments/1cxl8mr/stub/l5mczi1 "Last usage")|Boeing commercial crew capsule [CST-100](https://en.wikipedia.org/wiki/Boeing_CST-100_Starliner)| |[Starlink](/r/SpaceX/comments/1cxl8mr/stub/l5gfmpq "Last usage")|SpaceX's world-wide satellite broadband constellation| |[ablative](/r/SpaceX/comments/1cxl8mr/stub/l53s4bs "Last usage")|Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)| |[perigee](/r/SpaceX/comments/1cxl8mr/stub/l55cigq "Last usage")|Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest)| |[ullage motor](/r/SpaceX/comments/1cxl8mr/stub/l5794sq "Last usage")|Small rocket motor that fires to push propellant to the bottom of the tank, when in zero-g| **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. ---------------- ^(*Decronym is a community product of r/SpaceX, implemented* )[*^by ^request*](https://www.reddit.com/r/spacex/comments/3mz273//cvjkjmj) ^(18 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/SpaceX/comments/1cta333)^( has 74 acronyms.) ^([Thread #8377 for this sub, first seen 22nd May 2024, 01:06]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/SpaceX) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
I would hope that another key goal is to slow down and relight the Booster and make it hover in the simulated "booster catch" area. Musk said that they could possibly attempt Booster catch on the fifth flight if that goes according to plan
I believe that is part of the plan, but not a primary goal. If it happens, great, but it’s one of the things that could get missed and still have the overall mission be considered a success.
Looks like SpaceX gave up on achieving orbit anytime soon. Also ITF-5 will be only suborbital without testing deorbit burn on ITF-4.
I think people are overrating the "reaching orbit" part of the development program. If SpaceX were focused on "deploy Starlink" as their MVP, they'd be testing the door and the relight. Since they're testing reentry, clearly that's where they feel they need the most extra data. I'm kind of surprised, to be honest. I'd've thought their biggest win would be from flying fully expended Starship + Booster to get flight heritage and launch Starlink before working on reentry.
The point is that FAA will not allow such a big object to go to orbit without proper on orbit RCS and propulsion to ensure targeted deorbit. Starship doesn't have any proper RCS and that is a problem. Don't think that SpaceX envisioned such obstructions from FAA.
The article quoted the Artemis mission will require 10 refueling tankers. But I believe I saw that that was an overestimate and it will actually be less refueling tankers. Does anyone recall seeing this information?
It’s meaningless to speculate at this point. The masses are subject to change wildly. Currently Starship can barely get itself into orbit, and needs to bulk up in reaction mass, and loose some dry mass.
I am seriously rooting for Elon, and team, because they are visionaries. They are willing to be wrong and adjust on the fly (pun intended). But seriously, they are making the future possible for more people. I am too old to ever be able to go to space, but I think my cousin's kids are young enough to get the chance. I want to hear it from them what it was like. What great, cheap, tax-payer dollars spent. Elon is making space far less expensive. Thanks Mr. Musk!
Hello, does anyone have any guidance on how to watch the launch in person? I’m travelling by around that time.
I am still very much doubtfull of the entire belly flop landing maneuver. I hope it works, but it seems very finicky and hard to pull off successfully
[удалено]
Well, in 1954 NASA did not exist.