Commercial Crew - Discussion Thread 1

[Ike17055]

>
And if you are talking about the LAS how many tests have been conducted in the past? How many tests of the planned SpaceX or ULA LAS are there? It seems the LAS has minimal test data that it actually works.

SpaceX performed a Crew Dragon pad abort test 3 years ago, which is spot on the situation under discussion. An in-flight abort test at MaxQ is to be performed after the DM-1 uncrewed mission to ISS.

Pad abort test


Mashup of pad abort synched over the AMOS-6 failure. Do yourself a favor and turn off the audio.

one pad abort from a standstill is not a robust testing regimen, and if the premise is now that LAS is the main means of "protection" of the crew, you are going to need aq lot more assurances that abort is better than  a "maybe."

[abaddon]

With all the scrutiny regarding the fueling before/after crew boarding in SpaceX's proposed transportation architecture, I wonder if anyone has considered Boeing not conducting an in-flight abort test to be problematic?  Every US manned system except for Gemini and the Space Shuttle (neither of which included a LAS) has had or will have a LAS in-flight abort test, except for CST-100.

I know that an in-flight abort was not a required milestone, and SpaceX chose to submit a proposal with one while Boeing did not.  Of course, SpaceX submitted a proposal with fueling after boarding and it was accepted...

Apparently ASAP is fine launching on a system that is only tested in the most benign regime (pad escape) which, ironically, is the least likely environment it will ever be used in, due to the fueling before boarding and the low likelihood of an issue on pad after fuel loading when in stable replenish.

[Ike17055]

The point about no launch abort for Boeing has been raised before, and on its surface seems to be a good question. So have we ever heard justification for why the CC milestones never included a launch abort requirement?  How much might this decision have depended on the flight history of Atlas V, or does the introduction of new flight dynamics with the crew capsule added to the stack constitute enough design change that abort scenarios are not sufficiently known?

[envy887]

An abort has a high likleihood of resulting in serious injury or even death of crew. There is no "easy" ejection, and no "easy" abort.  Employing the LAS is not just an alternative way of deboarding the craft. It brings its own (substantial) risks.

Extraordinary claims require ext ordinary evidence. Care to provide some?

I never said it was always safe. I said it was a decent chance of survival. Even a slim chance of survival is infinitely better than the guaranteed no chance of survival both astronauts and pad crew have when something happens during boarding.

it's not an extraordinary claim. A basic understanding of the dynamics of abort, even unscientific can tell you that it is a dangerous situation. Very dangerous.You cannot predict with reliability how an abort unfolds, at least not as neatly as the pad abort tests where no real emergency exists.  yes, a chance of survival is better than no chance, but it is vastly nsufficient to build your entire lauch operations sequence around.

Nobody is building the prop load operation sequence around the abort capability, just as nobody is building the in-flight sequence around the abort capability. Having to use the abort system means automatic loss of mission and a very bad day. It's a backup system and can't be used to justify lower design margins on the primary and secondary systems.

...
 if the premise is now that LAS is the main means of "protection" of the crew, you are going to need aq lot more assurances that abort is better than  a "maybe."

It's not.

The main means of protection is a well-qualified and thoroughly tested pre-launch operational sequence.

Nope. you are engaged in what is called "motivational reasoning," a form of bias that is akin to rationalization.  Youand others here are ignoring all other facts put before you, and creating a strawman argument that everyone else is just "against the future." NASA does not have the luxury of such bias.  Until new designs prove themselves, you cannot attribute the positive attributes, such as a history of no explosions, to the new design. The posts stating that SpaceX is building a history is valid. But their practice still contradicts the baseline that the customer (NASA) has established for certification. It will be NASA's call ultimately whether that tanking/testing qualifies for certification. But SpaceX runs a huge risk if NASA decides it is not. SpaceX would do well in this circumstance to remember the old saying, "the customer is always right."

You are the one doing exactly that by saying that because load-then-board has been baselined for 50 years, it should be used on CC vehicles. Historical data form other dissimilar vehicles is virtually useless for justifying risk decision.

The only relevant launch data to any risk analysis on CC is from Atlas V and Falcon 9. Everything else is anecdotal at best.

[saliva_sweet]

it seems you are confirming my thesis, that greater reliance on LAS puts a premium on a more robust test regimen for LAS.

How much greater really? The LAS as currently tested is perfectly fine for flight apparently. A way more dynamic and dangerous phase than tanking as most would agree. Lasts about 20 minutes. Tanking is 30 minutes, about the same time.

[abaddon]

Back on page 52 I asked why this issue and these potential abort tests were occurring so late in the game- is that an unfair assumption? Where's Little Joe?

Abort tests occurring late are fine, as long as they are before a crewed flight, which they are.  In fact, the later the better, because that means the systems are as close to ready as possible.

As for Little Joe, for SpaceX it makes sense to use an F9, which is even better than a proxy rocket.  Orion will use an Orbital-ATK provided rocket more along the lines of LJ.  Boeing, as mentioned previously, does not have an in-flight abort milestone.

[abaddon]

How much might this decision have depended on the flight history of Atlas V

I don't see how flight history matters?  It is not possible to infer never needing the LAS in-flight no matter how successful the rocket is, or there wouldn't be a LAS at all.

or does the introduction of new flight dynamics with the crew capsule added to the stack constitute enough design change that abort scenarios are not sufficiently known?

Given that the program had to (expensively) modify the dynamics of the system with the addition of the "skirt" partway through development, I'd think they'd be more concerned about this.  I can only assume without any other data that ASAP is satisfied with the modeling and projections of the effectiveness of the LAS without an in-flight test.

[envy887]

.yes they are. the argument here has been that "even if fuel and go is more dangerous (and we don't know if it is or isn't) then the launch abort system will carry the astronauts away safely"...just read the previous posts.

That is not SpaceX's argument. They are saying that LAS is only part of the equation. Lower total exposure to risky events, and greater commonality with the well-tested F9 systems also make it safer than a modified F9.

[envy887]

How much might this decision have depended on the flight history of Atlas V

I don't see how flight history matters?  It is not possible to infer never needing the LAS in-flight no matter how successful the rocket is, or there wouldn't be a LAS at all.

or does the introduction of new flight dynamics with the crew capsule added to the stack constitute enough design change that abort scenarios are not sufficiently known?

Given that the program had to (expensively) modify the dynamics of the system with the addition of the "skirt" partway through development, I'd think they'd be more concerned about this.  I can only assume without any other data that ASAP is satisfied with the modeling and projections of the effectiveness of the LAS without an in-flight test.

Last we heard the abort stability was still a concern:

Boeing is addressing a risk that its abort system may not meet the program’s requirement to have sufficient control of the vehicle through an abort.

https://www.gao.gov/assets/700/691589.pdf

[Ike17055]

How much might this decision have depended on the flight history of Atlas V

I don't see how flight history matters?  It is not possible to infer never needing the LAS in-flight no matter how successful the rocket is, or there wouldn't be a LAS at all.

or does the introduction of new flight dynamics with the crew capsule added to the stack constitute enough design change that abort scenarios are not sufficiently known?

Given that the program had to (expensively) modify the dynamics of the system with the addition of the "skirt" partway through development, I'd think they'd be more concerned about this.  I can only assume without any other data that ASAP is satisfied with the modeling and projections of the effectiveness of the LAS without an in-flight test.

The skirt at least appears to be similar to the configuration used for their A-V satellite launches using the fairing. they may be seeing similar results from the simulations for Starliner?  ideally, flight testing would seem to be preferrable from a data standpoint.

[Ike17055]

.yes they are. the argument here has been that "even if fuel and go is more dangerous (and we don't know if it is or isn't) then the launch abort system will carry the astronauts away safely"...just read the previous posts.

That is not SpaceX's argument. They are saying that LAS is only part of the equation. Lower total exposure to risky events, and greater commonality with the well-tested F9 systems also make it safer than a modified F9.

the SpaceX defense is that it simply isn't an issue (due to commonality). NASA says "maybe it is." Posters on this forum are the ones caiming that LAS is what makes it adequate, not SpaceX in any official capacity. My premise is that those claims are wrong because LAS is not a guarantee, in the manner they are describing.

[envy887]

Nobody is building the prop load operation sequence around the abort capability, just as nobody is building the in-flight sequence around the abort capability. Having to use the abort system means automatic loss of mission and a very bad day. It's a backup system and can't be used to justify lower design margins on the primary and secondary systems.

i can't tell what you are talking about. The question has always been "how much do you want to count on a clean abort to balance off any added risk of a tanking problem?"  we know way too little about abort reliability to make such a trade.

Fix your quotes, please.

"We" aren't making the trade. NASA and SpaceX are, and they certainly have more data than we do.

However, the LAS is almost certainly not the primary justification for allowing load and go, since the probability of using the LAS has to be less than or equal to the acceptability of loss of mission and vehicle. Avoiding LOMV is highly desirable, almost as desirable as avoiding LOCV, so the primary justification will be the very high reliability of the qualified fueling systems and processes.

[jak Kennedy]

>
And if you are talking about the LAS how many tests have been conducted in the past? How many tests of the planned SpaceX or ULA LAS are there? It seems the LAS has minimal test data that it actually works.

SpaceX performed a Crew Dragon pad abort test 3 years ago, which is spot on the situation under discussion. An in-flight abort test at MaxQ is to be performed after the DM-1 uncrewed mission to ISS.

one pad abort from a standstill is not a robust testing regimen, and if the premise is now that LAS is the main means of "protection" of the crew, you are going to need aq lot more assurances that abort is better than  a "maybe."

Yes I know about the two aborts SpaceX has completed. My point is that with only 2 tests it is deemed safe and Boeing will have only 1 test. Why make such a big argument against Fuel and Go when so little testing has been performed for the LAS.

[Chris Bergin]

Only brought here because Jim was showing he is the world champion at showing a lack of civility (again!) but is this all a rehash of the rehashed points made in the Washington Post?

I guess that worked for them, but it doesn't work for us. We locked that thread for a reason and it wasn't so it could spread on to this one.

Make your closing remarks and I'll start a new thread.

[Eerie]

Do we know how critical the disagreement  between NASA and SpaceX really is? From a technical POV, can't SpaceX just do it the way NASA wants?

[Welsh Dragon]

An abort has a high likleihood of resulting in serious injury or even death of crew. There is no "easy" ejection, and no "easy" abort.  Employing the LAS is not just an alternative way of deboarding the craft. It brings its own (substantial) risks.

Extraordinary claims require ext ordinary evidence. Care to provide some?

I never said it was always safe. I said it was a decent chance of survival. Even a slim chance of survival is infinitely better than the guaranteed no chance of survival both astronauts and pad crew have when something happens during boarding.

it's not an extraordinary claim. A basic understanding of the dynamics of abort, even unscientific can tell you that it is a dangerous situation. Very dangerous.You cannot predict with reliability how an abort unfolds, at least not as neatly as the pad abort tests where no real emergency exists.  yes, a chance of survival is better than no chance, but it is vastly nsufficient to build your entire lauch operations sequence around.

I note your lack of evidence for your claim, and your appeal to the common sense fallacy.  Fact remains: there is no abort option during boarding after fuelling. Even a flawed abort option is better than none. Nobody is building any sequence around anything. But even if they were, you have a choice between building a sequence around an inherently survivable situation with no abort options or building a sequence around a option to abort (however potentially flawed) throughout. I'd pick the latter over the former any day. The bolded alone suggests you really agree with me, otherwise that statement would make no sense.

[Coastal Ron]

Do we know how critical the disagreement  between NASA and SpaceX really is?

I think this is the core question, since NASA makes the final decision, and SpaceX has to know what that is well in advance in order to stay on schedule.

The ASAP is an advisory board, and Congress is full of politicians that can elevate issues into the public space, so it's not like NASA can dismiss concerns out of hand. But NASA is responsible for making the final decision.

Hard to know what NASA is telling SpaceX though, and it's not like we have good visibility into SpaceX either.

From a technical POV, can't SpaceX just do it the way NASA wants?

I don't know if we have enough information to make informed guesses, but it's possible that SpaceX has designed their systems so that densified propellant is a requirement, not an option. And since densified propellant can't be kept cold enough on the pad while installing crew after fueling, that could mean that NASA is faced with a hard decision about SpaceX:

A. NASA continues to validate SpaceX designs, processes and procedures for 'fuel-n-go' so that they can justify their approval of this process.

B. NASA decides that 'fuel-n-go' is not going to be acceptable, and eliminates SpaceX as a crew transportation provider.

Am I missing an option if SpaceX can't do crew load after fueling with densified propellant?

[woods170]

The point about no launch abort for Boeing has been raised before, and on its surface seems to be a good question. So have we ever heard justification for why the CC milestones never included a launch abort requirement?  How much might this decision have depended on the flight history of Atlas V, or does the introduction of new flight dynamics with the crew capsule added to the stack constitute enough design change that abort scenarios are not sufficiently known?

Emphasis mine.
I see you managed to overlook my answer to that question entirely:

https://forum.nasaspaceflight.com/index.php?topic=35717.msg1818598#msg1818598

In short: NASA only required the pad abort and in-flight abort modes to be modeled. No actual test flights required. The pad abort tests from SpaceX and Boeing are entirely voluntary, as is the in-flight abort test from SpaceX.

NASA didn't require those abort tests because it deemed computer modeling of the aborts to be sufficient.

[woods170]

Do we know how critical the disagreement  between NASA and SpaceX really is? From a technical POV, can't SpaceX just do it the way NASA wants?

No, SpaceX can't without doing major mods to the launch procedures, fueling procedures, GSE and the vehicle and engines itself.

Switching to the deep cooled propellants was, for all practical intentions and purposes, a one-way trip. Going back to "regular-temperature" propellants has a very substantial price-tag. One that won't be covered by what SpaceX is getting for CCtCAP.

[woods170]

I don't know if we have enough information to make informed guesses, but it's possible that SpaceX has designed their systems so that densified propellant is a requirement, not an option. And since densified propellant can't be kept cold enough on the pad while installing crew after fueling, that could mean that NASA is faced with a hard decision about SpaceX:

A. NASA continues to validate SpaceX designs, processes and procedures for 'fuel-n-go' so that they can justify their approval of this process.

B. NASA decides that 'fuel-n-go' is not going to be acceptable, and eliminates SpaceX as a crew transportation provider.

Am I missing an option if SpaceX can't do crew load after fueling with densified propellant?

No. Those are the options. Either NASA certifies (or waivers) "fuel-n-go" or Crew Dragon won't be certified at all.