Commercial Crew - Discussion Thread 1

[envy887]

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.

NASA could shell out a whole bunch of money for SpaceX to modify a few F9s and requalify the Merlins with boiling props, and update the GSE and fueling procedures, and wait a year or so while that all gets done. And the resulting product IMO would be less safe as a result of the changes from the F9 baseline.

I think that's rather unlikely, although no less so than cutting Crew Dragon altogether. NASA needs 2 providers and is willing to pay for them.

[cscott]

A third option would be for NASA to come up with a set of additional tests NASA wants SpaceX to perform to validate the safety of their fueling procedure, or for NASA to require extra abort tests, etc.  The price (and time) of this additional "assurance" would determine whether SpaceX agreed to jump through the hoops or whether this effectively dropped SpaceX out of commercial crew.

[wolfpack]

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

We fuel airplanes with passengers aboard.

Guess we have to learn to do it with rockets, too.

[Brovane]

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.

Has that been confirmed by SpaceX that the F9 doesn't retain the ability to use non deep cooled propellants? 

[Lars-J]

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.

Has that been confirmed by SpaceX that the F9 doesn't retain the ability to use non deep cooled propellants?

It must, especially the upper stage. Because the propellant doesn't stay deep cryo cooled for long when much of it has been used up. Deep cryo is mostly a way to pack in more propellant in the same space. It does change the viscosity of the fluids, but presumably the engines compensate for that towards the end of the burns.

Or am I way off here? I don't think the F9 propellants are deep cryo during the landing burn.

[woods170]

A third option would be for NASA to come up with a set of additional tests NASA wants SpaceX to perform to validate the safety of their fueling procedure, or for NASA to require extra abort tests, etc.  The price (and time) of this additional "assurance" would determine whether SpaceX agreed to jump through the hoops or whether this effectively dropped SpaceX out of commercial crew.

That is in fact not a third option but an extension of option A.

[Comga]

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.

And I would put good odds on Option B, where NASA gets their crew transport from a familiar and competent supplier who can solve any technical problem in a comfortable manner, albeit at high cost. But for some that’s SEP. (Somebody Else’s Problem)

Except for ULA’s RD-180 supply and the switch to Vulcan.   Given that the planning horizon is only 6 years thru 2024, they seem to need less than a dozen flights and the ability to keep the Atlas V running in parallel with the Vulcan development. It may get pretty expensive on a per seat basis and hasten the “retirement” of the ISS, but every aspect makes some group happy. 

[Jim]

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

We fuel airplanes with passengers aboard.

Guess we have to learn to do it with rockets, too.

Not at all a valid analogy.  Cryogens are not involved.

[Hog]

So no crewed CC flights in 2018?
If ISS is splashed in 2024, approx. 12 crew rotations would be required and if she is splashed in 2028 approx. 20 crew rotations would be required.

As the lifeclock of the ISS keeps on ticking regardless of CCDev slippage, the window for actual "ISS Crew Transportation Services" grows smaller and smaller. 

Will Boeing and Space Exploration Technologies Corporation make more money developing and certifying the CST-100 Starliner/Atlas-V and Dragon-2/Falcon-9 than from their actual utilization?

It will be a great day when one of these USA build vehicles finally is able to claim this patch left on ISS by the last USA human rated vehicle to visit the ISS, OV-104 Atlantis when she undocked from ISS on July 19, 2011. 
The "gap" currently stands at 2486 or 6 years, 9 months, 20 days. 

Coincidentally the beginning of the 70's gap began on the same date with the Apollo Soyuz Test Project undocking also on July 19 but in 1975.  STS-1 with OV-101 Columbia launched on April 12, 1981 for a gap of 2095 days or 5 years, 8 months, 25 days.

[envy887]

Those are the options. Either NASA certifies (or waivers) "fuel-n-go" or Crew Dragon won't be certified at all.

And I would put good odds on Option B
...

I wouldn't, since the CC team doesn't consider load and go a significant schedule or budget risk.

[mme]

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

We fuel airplanes with passengers aboard.

Guess we have to learn to do it with rockets, too.

Here's Jim giving a longer explanation in late 2016:

...  Once fueled and into replenishment, the vehicle is a stable, quiescent condition, unlike during the process of loading propellant.

Leaks occur during loading
pressure vessels have issues during loading
spills occur during loading
cryogenic shock occurs during loading

This argument is literally years old. Loading cryogenic fuel and oxidizer is not at all the same as loading a fuel at ambient temperatures. Especially in a design that submerges complex plumbing and pressure vessels in a cryogen.

That doesn't mean SpaceX won't convince NASA that they have designs and procedures to reduce the risks to acceptable levels, but we really should not just claim it's no big deal.

[mn]

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.

Data does not usually lead the way.

Different people will look at the same data and reach vastly different conclusions. And that is even when trying your best to be 100% objective. (as we can see just be reading all the threads repeating this discussion over and over again)

Of course when the data is 100% one way and 0% the other way, then data will lead the way.

But in a case like this humans will have to make a decision without the benefit of overwhelming, clear, obvious data. And we can only hope it will turn out to be the right one.

[mn]

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.

Has that been confirmed by SpaceX that the F9 doesn't retain the ability to use non deep cooled propellants?

Though I don't recall them saying that, if they retained that option would we be going thru this discussion? Why would SpaceX insist on doing it their way if they can just as easily do it the NASA way?

Unless SpaceX is convinced that their way is much safer? (maybe they know something about the F9 that we don't and they don't consider stable replenish to be a safe state for any length of time ??)

[envy887]

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.

Has that been confirmed by SpaceX that the F9 doesn't retain the ability to use non deep cooled propellants?

Though I don't recall them saying that, if they retained that option would we be going thru this discussion? Why would SpaceX insist on doing it their way if they can just as easily do it the NASA way?

Unless SpaceX is convinced that their way is much safer? (maybe they know something about the F9 that we don't and they don't consider stable replenish to be a safe state for any length of time ??)

Even if they can do it without hardware changes, it's still not simple. There would be software change, GSE changes, and procedural changes. They would still effectively be operating a whole different vehicle just for crew, with the associated testing, qualification, and operations efforts and loss of commonality and flight heritage from the rest of F9 flights.

[Brovane]

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.

Has that been confirmed by SpaceX that the F9 doesn't retain the ability to use non deep cooled propellants?

Though I don't recall them saying that, if they retained that option would we be going thru this discussion? Why would SpaceX insist on doing it their way if they can just as easily do it the NASA way?

Unless SpaceX is convinced that their way is much safer? (maybe they know something about the F9 that we don't and they don't consider stable replenish to be a safe state for any length of time ??)

One of the key reasons for using deep cooled propellant was recovery of the booster by allowing additional performance increase.  Maybe using deep cooled propellant is necessary for booster recovery for the F9?  Maybe SpaceX doesn't want to have a different procedure for 1-2 commercial crew launches a year?

As far as I know, nobody from SpaceX has confirmed that the F9 doesn't retain the ability to use non deep cooled propellants.  I see a lot of speculation and assumptions on this thread that it doesn't retain this capability but I have yet to see confirmation from a reliable source that the F9 can only use deep cooled propellant now. 

To me if it was true that the F9 is only capable of using deep cooled propellant then I think this would have come out in the public space by now and the tone of the discussion would be different. 

[envy887]

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.

Has that been confirmed by SpaceX that the F9 doesn't retain the ability to use non deep cooled propellants?

Though I don't recall them saying that, if they retained that option would we be going thru this discussion? Why would SpaceX insist on doing it their way if they can just as easily do it the NASA way?

Unless SpaceX is convinced that their way is much safer? (maybe they know something about the F9 that we don't and they don't consider stable replenish to be a safe state for any length of time ??)

One of the key reasons for using deep cooled propellant was recovery of the booster by allowing additional performance increase.  Maybe using deep cooled propellant is necessary for booster recovery for the F9?  Maybe SpaceX doesn't want to have a different procedure for 1-2 commercial crew launches a year?

As far as I know, nobody from SpaceX has confirmed that the F9 doesn't retain the ability to use non deep cooled propellants.  I see a lot of speculation and assumptions on this thread that it doesn't retain this capability but I have yet to see confirmation from a reliable source that the F9 can only use deep cooled propellant now. 

To me if it was true that the F9 is only capable of using deep cooled propellant then I think this would have come out in the public space by now and the tone of the discussion would be different.

Unique new software and procedures for 1-2 flights per year actually increases risk compared to using the same F9 that has a long flight history and flies 30 times a year.

[Spindog]

I'm not sure why loading fuel and then the crew is off the table. Seems like the crew could load after fueling in about a 15 minute window, then do some quick pressure checks (having already done full system checks before loading fuel). I'd bet this could be easily done and ground crew clear away for launch inside of 10 or 15 minutes. Might consider building a "close as possible" waiting bunker for the crew and ground staff to stay as close to the pad during fueling to reduce travel time. This isn't Apollo and there's no reason the astronauts would have to sit in the rocket for an hour plus of checks. Why wouldn't this work?

[rliebman]

a thought: SX could select 1 - N upcoming flights and model the fuel / load / go approach and validate the KPIs / data associated.  a static fire opportunity might be a logical approach.  moreover, they could repeat this approach as part of the validation of the Block 5 reuse cycles.  it is not perfect, but.......

[envy887]

a thought: SX could select 1 - N upcoming flights and model the fuel / load / go approach and validate the KPIs / data associated.  a static fire opportunity might be a logical approach.  moreover, they could repeat this approach as part of the validation of the Block 5 reuse cycles.  it is not perfect, but.......

This reduces the performance of the launch vehicle (which reduces margin and increases risk) and means that high performance launches have to go on a unique configuration (which reduces flight heritage and increases risk).

[SWGlassPit]

I'm not sure why loading fuel and then the crew is off the table. Seems like the crew could load after fueling in about a 15 minute window, then do some quick pressure checks (having already done full system checks before loading fuel). I'd bet this could be easily done and ground crew clear away for launch inside of 10 or 15 minutes. Might consider building a "close as possible" waiting bunker for the crew and ground staff to stay as close to the pad during fueling to reduce travel time. This isn't Apollo and there's no reason the astronauts would have to sit in the rocket for an hour plus of checks. Why wouldn't this work?

It takes a lot longer that to get a) loaded up, b)strapped in, c) verify crew-hardware interfaces (comm checks, suit airflow, etc), d) close the hatch, e) perform a leak check to verify hatch seal integrity, and f) have the closeout crew retreat to a safe location.