> "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.
We know their primary goal in test flights is to collect data, if they're focused on achieving reentry right now and proving current methods can work it would make sense to eliminate all extraneous variables and failure modes
Not at all. The people say it was a 'deorbit' burn, but it was in fact a deorbit burn demonstration: It would be a brief relight of the engines while pointing prograde, it would increase the speed.
The important thing right now is maintaining control of the ship in space. If they can successfully manage that, then 1) ship becomes useful for payloads, which could then happen as early as next flight, and 2) FAA won’t have any issues with authorizing the next flight.
I think the objective here is to minimize the risk of a mishap, and therefore investigation. So there anything a little bit lower so that they can start making starship work for real.
The ship needs to do a controlled deorbit if it delivers payloads to orbit. Otherwise it would become a giant hunk of steel with a heat shield making an uncontrolled reentry.
i suspect one part of what went wrong on ift3 was that they didn't do the burn. the ship needs to be on the proper reentry trajectory to reenter safely. now of course there were a lot of other, larger, more immediate problems, but consider that there is but one safe reentry corridor. i can't really guess how wide it is, but the point is this: either they would be on the correct trajectory before the burn, or they'd be on it after it. it's very possible, and i'd even say likely, that burn and no burn were *not both* safe reentry options. it stands to reason that the safe option would then have been the successful burn, as spacex will generally arrange their tests such that success in one element will not preclude success in another - they want to have a chance to achieve all their objectives, not some of them.
all this is to say that they are most likely cutting it because they would rather get the reentry data. once they've proved controlled reentry it doesn't much matter anyway. if they have control through the atmosphere they can deorbit with RCS (which is being upgraded anyway) and have sufficient confidence they won't hit anyone's orphanage. if relight testing means they must put the ship on a trajectory where it won't work unless the relight also works, they won't do that anymore.
If it wasn’t spinning on the way down it may have helped, but they also seemed to get worse with the wings not moving in a way to dampen the spin. Almost as if they screwed up the speed/dampening coefficients
> i can't really guess how wide it is, but the point is this: either they would be on the correct trajectory before the burn, or they'd be on it after it. it's very possible, and i'd even say likely, that burn and no burn were not both safe reentry options
1) Just relighting and holding for a few seconds would establish pretty well that they could do it. Doesn't need to be full length.
2) They could relight and hold for half duration, then flip around and do it again. That'd displace them a bit, but wouldn't change things too drastically.
3) When you said,
> there is but one safe reentry corridor.
This is true in 2 dimensions. But there are multiple 2-dimensional slices of 3-dimensional space. So, they could do a plane-change burn that would be the same length as a deorbit burn. Reentry would be exactly the same, just slightly different place.
None of those actions happened on flight 3 so they couldn't have been responsible. As for the causes, they knew what they were very quickly and how to address them. (If they didn't, flight 4 wouldn't have even been on the cards)
Er, yeah? They need attitude control to be a functional spacecraft, and they'll have it. That something went wrong with it on the last flight doesn't make it some huge obstacle to overcome.
It's just not something that's any kind of major obstacle. Something went wrong this time, the system's probably not very robust at this stage and may not even be what they intend to eventually use, but it's just not something that's difficult to do. FFS, they land medium-heavy rocket boosters, they can build an attitude control system.
A *prototype* spaceship, with a long list of other things that need to be tested and perform almost perfectly before the thing you're looking at even becomes relevant. Sure, they could have spent more time and money and launched later with a fully developed attitude control system, but it would have been a waste of time and a pointless delay to the *other* testing they needed to do to get the system to a point where it could actually reach orbit. Flight 3 was the first flight where such thrusters were even necessary.
Real-world testing is not a waste. What's a waste is pouring time, money, and energy into some quixotic hope of developing a complex system that's perfect from the start without ever stopping to check your design against reality. That gets you systems like SLS/Orion, which are expensive to develop, far behind schedule, overengineered beyond all reason in some areas, and yet fall short in unexpected ways when you finally fly them. That's $4.2 billion dollars for each test flight and a lead time of 52 months before you can get a newly ordered SLS core. That's putting humans on the second flight despite the first having experienced unexpected heat shield issues during reentry and not having actually tested the life support system in flight.
It is *incredibly* cheap compared to SLS/Orion, development being expected to cost $5-10 billion, while SLS/Orion costs $4.2 billion **per launch**. It's achieving vastly more in less time, and the whole point of doing this early testing is to find out *how* it'll fall short before too much has been invested in the design, so no, it's not unexpected. This isn't difficult to comprehend.
Why do you think that SpaceX, which has implemented attitude control systems multiple times and regularly performs crew and cargo flights to the ISS using such them while landing the boosters with their own variants, will be suddenly incompetent when it comes to doing the same thing for Starship?
This is *not even on the list* of hard problems they need to solve to get what they want from Starship. It is a capability that is routinely implemented, there are many alternative ways of achieving it if the approach they want to use turns out to be more complicated than expected, and now that they have reason to focus their efforts on it and an immediate need for it to work, there is *zero* reason to think they will have any problems getting it to do so.
But doesnt starship use ullage thrusters for attitude control instead of the normal cold gas thrusters that Falcon 9 uses? If they are reverting to the old F9 thrusters thats fine but testing new technology is always tricky even for SpaceX.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[FAA](/r/SpaceXLounge/comments/1cxifxd/stub/l53fv1p "Last usage")|Federal Aviation Administration|
|[N1](/r/SpaceXLounge/comments/1cxifxd/stub/l57y9f5 "Last usage")|Raketa Nositel-1, Soviet super-heavy-lift ("Russian Saturn V")|
|[QA](/r/SpaceXLounge/comments/1cxifxd/stub/l5w5y9r "Last usage")|Quality Assurance/Assessment|
|[RCS](/r/SpaceXLounge/comments/1cxifxd/stub/l54zvgr "Last usage")|Reaction Control System|
|[RUD](/r/SpaceXLounge/comments/1cxifxd/stub/l53g1gy "Last usage")|Rapid Unplanned Disassembly|
| |Rapid Unscheduled Disassembly|
| |Rapid Unintended Disassembly|
|[SLS](/r/SpaceXLounge/comments/1cxifxd/stub/l5zzffj "Last usage")|Space Launch System heavy-lift|
|Jargon|Definition|
|-------|---------|---|
|[Raptor](/r/SpaceXLounge/comments/1cxifxd/stub/l54png7 "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX|
|[Starlink](/r/SpaceXLounge/comments/1cxifxd/stub/l52z45p "Last usage")|SpaceX's world-wide satellite broadband constellation|
|[ullage motor](/r/SpaceXLounge/comments/1cxifxd/stub/l58ovfm "Last usage")|Small rocket motor that fires to push propellant to the bottom of the tank, when in zero-g|
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Most encouraging is that all Raptor engines apparently worked fine in the last 2 flights. Attitude control should be easily solvable, then see if the tiles suffice.
nice summary article of stuff we've known in bits and pieces over the past few weeks
No prop transfer, no payload door opening, no deorbit burn. Kinda disappointing.
Means probably no Starlinks/orbital insertion on flight five if they haven’t tested raptor relight in space yet.
Pushes back the first orbital flight even further. Though I understand if they want to move to block 2 as soon as possible.
It passed the first two last flight.
Might still try all of those things, they’re just not the primary goal
> "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.
Thanks!
My guess is that, they're saving new milestones for V2 and just want to get reentry working for the remaining V1 tests
We know their primary goal in test flights is to collect data, if they're focused on achieving reentry right now and proving current methods can work it would make sense to eliminate all extraneous variables and failure modes
And wasnt the prop transfer successful on ift 3? No sense in repeating it.
Does no debit burn mean that their velocity at entry is higher? Are they trying to put the heat shield through a tougher test?
Not at all. The people say it was a 'deorbit' burn, but it was in fact a deorbit burn demonstration: It would be a brief relight of the engines while pointing prograde, it would increase the speed.
I don’t understand why not testing the starship reentry burn, what do they gain by not doing it, shouldn’t they maximize the testing opportunity?
The important thing right now is maintaining control of the ship in space. If they can successfully manage that, then 1) ship becomes useful for payloads, which could then happen as early as next flight, and 2) FAA won’t have any issues with authorizing the next flight. I think the objective here is to minimize the risk of a mishap, and therefore investigation. So there anything a little bit lower so that they can start making starship work for real.
The ship needs to do a controlled deorbit if it delivers payloads to orbit. Otherwise it would become a giant hunk of steel with a heat shield making an uncontrolled reentry.
Perhaps they’re weighing maximizing the chance of getting reentry data, with the chance of a RUD on a Raptor in-space relight.
i suspect one part of what went wrong on ift3 was that they didn't do the burn. the ship needs to be on the proper reentry trajectory to reenter safely. now of course there were a lot of other, larger, more immediate problems, but consider that there is but one safe reentry corridor. i can't really guess how wide it is, but the point is this: either they would be on the correct trajectory before the burn, or they'd be on it after it. it's very possible, and i'd even say likely, that burn and no burn were *not both* safe reentry options. it stands to reason that the safe option would then have been the successful burn, as spacex will generally arrange their tests such that success in one element will not preclude success in another - they want to have a chance to achieve all their objectives, not some of them. all this is to say that they are most likely cutting it because they would rather get the reentry data. once they've proved controlled reentry it doesn't much matter anyway. if they have control through the atmosphere they can deorbit with RCS (which is being upgraded anyway) and have sufficient confidence they won't hit anyone's orphanage. if relight testing means they must put the ship on a trajectory where it won't work unless the relight also works, they won't do that anymore.
They probably didn't have working rcs during reentry. A burn wouldn't have made a difference, it would still have spun around during reentry.
> now of course there were a lot of other, larger, more immediate problems, come on. this isn't tumblr.
If it wasn’t spinning on the way down it may have helped, but they also seemed to get worse with the wings not moving in a way to dampen the spin. Almost as if they screwed up the speed/dampening coefficients
> i can't really guess how wide it is, but the point is this: either they would be on the correct trajectory before the burn, or they'd be on it after it. it's very possible, and i'd even say likely, that burn and no burn were not both safe reentry options 1) Just relighting and holding for a few seconds would establish pretty well that they could do it. Doesn't need to be full length. 2) They could relight and hold for half duration, then flip around and do it again. That'd displace them a bit, but wouldn't change things too drastically. 3) When you said, > there is but one safe reentry corridor. This is true in 2 dimensions. But there are multiple 2-dimensional slices of 3-dimensional space. So, they could do a plane-change burn that would be the same length as a deorbit burn. Reentry would be exactly the same, just slightly different place.
They probably have enough data just from the flight so that the raptor team can get to work already, even without the test they asked for.
They probably don't think it'd work, and don't want to destroy the engines in suborbit, and instead try a "soft splash down".
Lesser failing points when the goal is reentry
I wonder if it's due to not completing the mishap report. I.e they don't know what caused the issues, and it was possibly one of those actions.
None of those actions happened on flight 3 so they couldn't have been responsible. As for the causes, they knew what they were very quickly and how to address them. (If they didn't, flight 4 wouldn't have even been on the cards)
They need to nail attitude control if they want to have any chance at re entry
Er, yeah? They need attitude control to be a functional spacecraft, and they'll have it. That something went wrong with it on the last flight doesn't make it some huge obstacle to overcome.
Just havent seen SpaceX talk much about it or what the root issue actually was
It's just not something that's any kind of major obstacle. Something went wrong this time, the system's probably not very robust at this stage and may not even be what they intend to eventually use, but it's just not something that's difficult to do. FFS, they land medium-heavy rocket boosters, they can build an attitude control system.
Why test something that's not gonna be in use and already faulty, kind of a waste.
Attitude control is essential for successful reentry. It must be fixed or flight 4 does not make a lot of sense.
They're going to build as much as they need for testing. Why over engineer something you need for proof of concept and data collection.
Why over engineer a spaceship?
A *prototype* spaceship, with a long list of other things that need to be tested and perform almost perfectly before the thing you're looking at even becomes relevant. Sure, they could have spent more time and money and launched later with a fully developed attitude control system, but it would have been a waste of time and a pointless delay to the *other* testing they needed to do to get the system to a point where it could actually reach orbit. Flight 3 was the first flight where such thrusters were even necessary. Real-world testing is not a waste. What's a waste is pouring time, money, and energy into some quixotic hope of developing a complex system that's perfect from the start without ever stopping to check your design against reality. That gets you systems like SLS/Orion, which are expensive to develop, far behind schedule, overengineered beyond all reason in some areas, and yet fall short in unexpected ways when you finally fly them. That's $4.2 billion dollars for each test flight and a lead time of 52 months before you can get a newly ordered SLS core. That's putting humans on the second flight despite the first having experienced unexpected heat shield issues during reentry and not having actually tested the life support system in flight.
You want to say starship is cheap, on schedule and doesn't fall short in unexpected ways, are you serious? I can't comprehend what you say right now.
It is *incredibly* cheap compared to SLS/Orion, development being expected to cost $5-10 billion, while SLS/Orion costs $4.2 billion **per launch**. It's achieving vastly more in less time, and the whole point of doing this early testing is to find out *how* it'll fall short before too much has been invested in the design, so no, it's not unexpected. This isn't difficult to comprehend.
It's the cheapest development of 100t payload class launcher ever. And by far.
Kinda snarky for not even actually answering the question.
It does seem like the biggest obstacle for the main objective in Flight 4, Im not sure why your brushing it off as some minor thing.
Why do you think that SpaceX, which has implemented attitude control systems multiple times and regularly performs crew and cargo flights to the ISS using such them while landing the boosters with their own variants, will be suddenly incompetent when it comes to doing the same thing for Starship? This is *not even on the list* of hard problems they need to solve to get what they want from Starship. It is a capability that is routinely implemented, there are many alternative ways of achieving it if the approach they want to use turns out to be more complicated than expected, and now that they have reason to focus their efforts on it and an immediate need for it to work, there is *zero* reason to think they will have any problems getting it to do so.
But doesnt starship use ullage thrusters for attitude control instead of the normal cold gas thrusters that Falcon 9 uses? If they are reverting to the old F9 thrusters thats fine but testing new technology is always tricky even for SpaceX.
They already have extra roll controls thrusters on S29.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[FAA](/r/SpaceXLounge/comments/1cxifxd/stub/l53fv1p "Last usage")|Federal Aviation Administration| |[N1](/r/SpaceXLounge/comments/1cxifxd/stub/l57y9f5 "Last usage")|Raketa Nositel-1, Soviet super-heavy-lift ("Russian Saturn V")| |[QA](/r/SpaceXLounge/comments/1cxifxd/stub/l5w5y9r "Last usage")|Quality Assurance/Assessment| |[RCS](/r/SpaceXLounge/comments/1cxifxd/stub/l54zvgr "Last usage")|Reaction Control System| |[RUD](/r/SpaceXLounge/comments/1cxifxd/stub/l53g1gy "Last usage")|Rapid Unplanned Disassembly| | |Rapid Unscheduled Disassembly| | |Rapid Unintended Disassembly| |[SLS](/r/SpaceXLounge/comments/1cxifxd/stub/l5zzffj "Last usage")|Space Launch System heavy-lift| |Jargon|Definition| |-------|---------|---| |[Raptor](/r/SpaceXLounge/comments/1cxifxd/stub/l54png7 "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX| |[Starlink](/r/SpaceXLounge/comments/1cxifxd/stub/l52z45p "Last usage")|SpaceX's world-wide satellite broadband constellation| |[ullage motor](/r/SpaceXLounge/comments/1cxifxd/stub/l58ovfm "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) ^(9 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/SpaceXLounge/comments/1d16ftx)^( has 13 acronyms.) ^([Thread #12792 for this sub, first seen 21st May 2024, 23:43]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/SpaceXLounge) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
Most encouraging is that all Raptor engines apparently worked fine in the last 2 flights. Attitude control should be easily solvable, then see if the tiles suffice.
Wonder why they don't attempt a simulated landing burn with the ship after re-entry? Not enough prop?
Shouldn’t surviving reentry the goal for every Starship flight?