Commercial Crew - Discussion Thread 1

[Ike17055]

envy887 pretty much hit the nail on the head. And I still don’t understand that if NASA has a problem with loading with crew onboard how they can justify fuel transfers in space. I know they are not the same but there is minimal historic data and it doesn’t appear to be a problem.

Specious logic.  Undoubtedly, NASA would be the first to state that transfers in space would need to be tested and re-tested to be considered reliable.

[joek]

...  If everyone who supports new fueling wants to cite reliance on the LAS as their guaranteed safety net, then we better spend a lot more effort on testing the safety net.

As opposed to what?  The fact that because the alternative has not resulted in fatalities means it is better?  That is about as screwed up a justification as I have ever heard.

[Ike17055]

actually, you are just proving you have no idea what you are talking about. read the posts, dude.TEST TEST TEST Then you willl KNOW KNOW KNOW.  Denying the need to do so is the only thing that is "screwed up logic" here.

[speedevil]

actually, you are just proving you have no idea what you are talking about. read the posts, dude.TEST TEST TEST The you willl KNOW KNOW KNOW.  Denying the need to do so is the only thing that is "screwed up logic" here.

Testing once, or even five times tells you little or nothing about failures that will happen once every ten flights.

[rcoppola]

IIRC both Lightfoot and Gerst have said that NASA will let the data lead the way towards approval or lack thereof wrt fueling.

SpaceX had, what I would think, was a robust COPV 2.0 test campaign at McGregor. They'll need 7 successful Block-5 launches. They'll have all (most?) of those cores returned for further inspection and verification. And then a few of those probably re-flown, returned and inspected again with a total pre-crew launch campaign far greater than the original 7 needed for Block-5 Crew Certification.

Let the data lead the way. NASA seems to be willing to do just that. Sounds good to me.

[Ike17055]

...  If everyone who supports new fueling wants to cite reliance on the LAS as their guaranteed safety net, then we better spend a lot more effort on testing the safety net.

As opposed to what?  The fact that because the alternative has not resulted in fatalities means it is better?  That is about as screwed up a justification as I have ever heard.

the current method of record ("fuel first") has established a threshold of reliability for safety that any new practice should also have to prove it can attain.  So, to answer your question, YES, it is "better" until any new method can prove otherwise. 

[Ike17055]

actually, you are just proving you have no idea what you are talking about. read the posts, dude.TEST TEST TEST The you willl KNOW KNOW KNOW.  Denying the need to do so is the only thing that is "screwed up logic" here.

Testing once, or even five times tells you little or nothing about failures that will happen once every ten flights.

just as Challenger and Columbia reminded us...but its fallibility it does not mean to throw caution to the wind. More testing equals a higher confidence level that you are achieving reliability (not perfection). Acceptable risk is vastly differen than blind risk.

[Ike17055]

IIRC both Lightfoot and Gerst have said that NASA will let the data lead the way towards approval or lack thereof wrt fueling.

SpaceX had, what I would think, was a robust COPV 2.0 test campaign at McGregor. They'll need 7 successful Block-5 launches. They'll have all (most?) of those cores returned for further inspection and verification. And then a few of those probably re-flown, returned and inspected again with a total pre-crew launch campaign far greater than the original 7 needed for Block-5 Crew Certification.

Let the data lead the way. NASA seems to be willing to do just that. Sounds good to me.

wiser words never spoken (or posted).

[the_other_Doug]

Jim keeps repeating that the fuel load period is inherently more dangerous than a "stable" replenishment period.

From a history and experience standpoint -- not your gut feeling "so many things are changing, it's so dynamic, it just HAS to be more dangerous" argument -- why?

How many rockets have had serious problems in the past (let's be generous) 25 years during fuel loading?  Versus how many have had serious problems after fuel loading, or after engine ignition?  Or, in most cases, have had no problems at all?

I can name one (count 'em, one) example of an incident during fueling -- AMOS 6.

What others?

Again, this comes down to whether it is inherently more dangerous to a fuel a rocket -- generically, *any* rocket -- after crew boards than before.

And again, if NASA is satisfied that the AMOS 6 incident has been properly identified and mitigated (meaning the Falcon ought to be MORE safe during fuel loading than other rockets, since it has gone through a multi-million-dollar, labor-intensive review of its hardware and its fuel loading processes to mitigate any such problems in the future), what beyond "we've always done it the other way" is a logical case against boarding and then fueling?

Jim?  What other examples of what could be a crew-endangering situation have happened during fuel loading in the past 25 years?

Any?  At all?

Where is the evidence that rockets are so much more likely to blow up during fueling that SpaceX must be forced into a far different process than they have repeatedly shown, after the AMOS 6 mitigation efforts, to be safe and effective?

Sounds just like the Apollo mode decision discussion --  and Jerry Weisner's "it just HAS to be more dangerous to go LOR.  It just FEELS more dangerous.  No, I don't have actual DATA that says so, just my gut feeling.  But that's enough for me to try and stop you from using a mode I just KNOW has to be more dangerous, even if I have no data to prove it."

And we know how that one turned out...

[rayleighscatter]

So what are you saying - remove the densified propellents, change the gse, change the loading procedures all for how many flights per year  - 1/2?

Wouldn't that INCREASE the chance of something bad happens as you now have a configuration you don't regularly fly?

Saying that F9 with crew onboard should launch in a fundamentally different configuration than other F9 flights (ie nondensified propellants) potentially increases risk much more than it mitigates it.

...

If SpaceX can't manage that disparity then perhaps Astronauts aren't a cargo they should be carrying.

You edited out the context from my post.

The part you edited out said crew launches are fundamentally different.

With that context if they can't manage the fact that crewed launches are so inherently different than everything else then maybe they shouldn't be doing it.

[Kansan52]

"Let the data lead the way" sounds good but does not inspire confidence for me. Jim's comment seems (to me) reflect NASA's position (at least the decision makers there). Decision makers can ignore data that doesn't meet their position.

[envy887]

If NASA had boarded all those crews first, the record would be the same. That's basically just another way of saying "we've always done it this way", which is not a valid justification for anything.

uh, no, it really isn't saying that at all... there is a middle ground. continue testing densified fuels on uncrewed.

"fools rush in where angels fear to tread"

Yes, it is saying exactly that. That particular data set does not invalidate the hypothesis that load and go is just as safe, because none of them had an issue that would have caused a failure with load and go.

And what do you think SpaceX is doing, other then testing on uncrewed launches? They will have around 200 load cycles and 50 flights after fixing the issues found in the AMOS anomaly, and before flying any crew.

[docmordrid]

So Bezos pet attack dog is now promoting itas 'SpaceX is dangerous' narrative to the space media.

Classy, Jeff, real classy.

https://twitter.com/NASASpaceflight/status/993510596753666049?s=19

Chris B - NSF @NASASpaceflight
It appears the Wash Post has decided to "cold call" space flight reporters to push their "SpaceX is dangerous!!" article (that isn't even new news). I didn't sign up to any of their mailing lists.

Check out the dramatics in the abstract.

PS It's SpaceX, not Space X 🤦‍♂️ pic.twitter.com/xZVRMzYvfi

[envy887]

actually, you are just proving you have no idea what you are talking about. read the posts, dude.TEST TEST TEST The you willl KNOW KNOW KNOW.  Denying the need to do so is the only thing that is "screwed up logic" here.

Testing once, or even five times tells you little or nothing about failures that will happen once every ten flights.

just as Challenger and Columbia reminded us...but its fallibility it does not mean to throw caution to the wind. More testing equals a higher confidence level that you are achieving reliability (not perfection). Acceptable risk is vastly differen than blind risk.

RAther than simply testing a lot, it's far more important that your testing validates your design models so that you can accurately predict failure and know exactly how much safety margin you have.

Challenger and Columbia mostly showed that the Shuttle's failure modes were very poorly understood. NASA did not even get the foam shedding fixed properly post-Columbia, and experienced the same failure mode on the RTF though fortunately without LOCV.

[daveklingler]

So Bezos pet attack dog is now promoting itas 'SpaceX is dangerous' narrative to the space media.

Classy, Jeff, real classy.

That's...extremely silly.

Christian Davenport has been writing on space and defense for about 18 years, and although I wouldn't consider him to be deeply well-versed technically, he's still better informed than the vast majority of the people reporting on space.

The person who promo'd the story is pretty wet behind the ears. She graduated last year with a degree in communications, and I guess her job is basically pushing Post stories to anybody she can in order to get them more widely read.  In a newspaper, she's the modern equivalent of the mail girl.

Look...obviously the safest possible way to launch people would be *after* the rocket has already achieved orbit, if that could be done. Putting them on the rocket before it's propped is very obviously safer than after it's propped. If there's a loading accident and the crew is in a blockhouse, they're safe, from the rocket, anyway.  It's foolish to argue that they're not.

But that idea is nearly meaningless.

The question isn't whether they're safer, but how much safer. There's already been a lot of analysis done on SpaceX's launch loading system, probably tens of thousands of man-hours, if not more. There will be a great deal of hours spent analyzing Block 5 launches before humans fly aboard it. With the data available, it will be "safe enough" before humans get on board. And if there's an accident, then it will be something that was unforeseen despite extremely exhaustive study.

Now that I've restated the obvious, let's give it a rest. Sheesh.

[daveklingler]

So Bezos pet attack dog is now promoting itas 'SpaceX is dangerous' narrative to the space media.

Classy, Jeff, real classy.

https://twitter.com/NASASpaceflight/status/993510596753666049?s=19

Chris B - NSF @NASASpaceflight
It appears the Wash Post has decided to "cold call" space flight reporters to push their "SpaceX is dangerous!!" article (that isn't even new news). I didn't sign up to any of their mailing lists.

Check out the dramatics in the abstract.

PS It's SpaceX, not Space X 🤦‍♂️ pic.twitter.com/xZVRMzYvfi

If you really want to get mad and spit bile at somebody, spit it at the "NASA advisors". 

[envy887]

...
Putting them on the rocket before it's propped is very obviously safer than after it's propped.
...

That's not at all obvious.

Load and go mitigates some risks and increases other risks. The balance is in the details, which we don't have.

...
With the data available, it will be "safe enough" before humans get on board. And if there's an accident, then it will be something that was unforeseen despite extremely exhaustive study.
...

Absolutely.

[yokem55]

The one idea that I haven't seen evaluated is the possibility of having a return feed at the top of the lox tanks that feeds back down through the lox tank to an exit port on the umbilical or TSM allowing a steady flow of sub-cooled lox back into the tank. This presumes that the lox will stratify as it warms, leaving the warmest lox at the top.

If that were to work, SpaceX could run a ' steady re-chill" of the vehicle that would relatively match the the "steady replenish" of boiling temp vehicles. That could potentially allow time to board after fueling.

[Comga]

So what else can SpaceX do to convince NASA that their launches are adequately safe?

How about just keep doing what they're doing right now: keep the steamroller going and avoid RUD. If they keep the current launch rate, by the time they launch crew for the first time they would have completed ~100 tanking operations post AMOS-6, and by the time they start flying post certification mission it would be close to 140, similar to the # of successful Soyuz missions. I think this together with their LoC calculation should be enough to convince NASA the procedure is safe.

They also do a lot of tankings at McGregor: all the qualification testing and all the flight acceptance testing requires tanking each stage. They will probably have completed over 200 propellant load sequences post-AMOS before a crew ever flies.

And yet SpaceX is going to “COPV 2.0”
Will they be more or less reliable and expensive than the “COPV 1.1” used successfully in all those tests and flights?
Or is this another perceived risk that NASA with their $3B/yr ISS budget & alternative launch provider feels they can afford to buy down and/or wait for?

[woods170]

I think we all understand that doing it the SpaceX proposed way does increase risk for the astronauts.

Do we? I don't. Let's compare some scenarios, shall we:

1) Board astronauts
2) Start fuelling
3) Something goes wrong with fuelling, leads to RUD
4) LAS activates, giving crew a very decent chance of survival (pad crew is miles away in safety already)

Or an alternative scenario:

1) Fuel
2) Start boarding astronauts
3) Rocket undergoes RUD during boarding
4) Both astronauts and pad crew have zero chance of survival.

Unless you assume the chance of killing the crew in a LAS abort is bigger than the chance of killing them during a incident while boarding on top of a fuelled vehicle, or can give a 100% guarantee nothing can go wrong with a fuelled vehicle, boarding first seems to me to always be the better option. Bottom line: crew on board during fuelling: abort option available during entire fuelling process. Crew boarding after fuelling: significant period without any abort option. On balance, fuelling after boarding likely less risky for astronauts, infinitely less risky for pad crew.

this and other posts make a huge mistake in establishing equivalency of the two scenarios. Besides the ease with which assumptions about safety are thrown around, the fact remains that current practice does have a 50 year process history of successful practice. The "new way" has zero experience (WITH CREW). While no one says that all things must remain unchanged forever, or that there is only one way to do things, the risks in allowing a change of this magnitude cannot be wished away or dismissed simply because the abort system is available. An abort has a high likleihood of resulting in serious injury or even death of crew.

Emphasis mine.

Your statement is exactly the sort of assumption you chastised Welsh Dragon over.
There has ever been only one "real life" example of a crew riding the abort system: Soyuz T10-1.
Other than being badly bruised the crew lived to tell the tale and, most importantly, did NOT require medical attention after the abort.

So much for your "high likelihood of serious injury or death".