Commercial Crew Schedule Analysis

[rockets4life97]

However I suspect that after this latest incident, NASA is going to have even more reason to want the crew loaded after the propellant and NASA is the customer.   

I think the reaction to this event will be the opposite. All the evidence we have (including Elon Musk's comments on twitter) indicate that Crew Dragon would have gotten away and this explosion was pretty fast.

To your other point, I don't think SpaceX is going away from densified propellents. It factors to heavily in to their reusability plans. So, NASA will work with SpaceX on it until they are happy. However, I don't see NASA forcing SpaceX to go away from densified propellents.

[yoram]

Is it known why SpaceX switched to water based landing for D2?

[TrevorMonty]

Is it known why SpaceX switched to water based landing for D2?

A reliable proven system.

Parachute with propulsion cushioning on land and full propulsive landing are going to take a while to develop. Both really need to be proven reliable with multiple cargo flights.

[Brovane]

However I suspect that after this latest incident, NASA is going to have even more reason to want the crew loaded after the propellant and NASA is the customer.   

I think the reaction to this event will be the opposite. All the evidence we have (including Elon Musk's comments on twitter) indicate that Crew Dragon would have gotten away and this explosion was pretty fast.

To your other point, I don't think SpaceX is going away from densified propellents. It factors to heavily in to their reusability plans. So, NASA will work with SpaceX on it until they are happy. However, I don't see NASA forcing SpaceX to go away from densified propellents.

We are getting off track from the original question. 

Can the latest version of the F9 launch without using densified propellant?  I am not really interested in debating about whether our not the astronauts should board before after our before propellant loading. 

[woods170]

Is it known why SpaceX switched to water based landing for D2?

It was mandated by NASA for early missions.

[the_other_Doug]

We are getting off track from the original question. 

Can the latest version of the F9 launch without using densified propellant?  I am not really interested in debating about whether our not the astronauts should board before after our before propellant loading.

Gut response -- maybe, but possibly not at all.

First off, the prop loading setup now deep-chills both LOX and RP-1.  Is it possible to bypass the deep coolers at this point?  Depending on how they are installed, perhaps not.  I seriously doubt it's as simple as "well, just turn off the refrigeration."

Second, the turbopumps, pressurization systems, etc., have now been optimized for the deep-chilled propellants.  Will everything work fine without the deep cooling?  Maybe, but possibly not.

Finally, the main reason for propellant densification via deep-cooling was, and is, to be able to load more prop on the bird.  With less prop, you get less total energy out of your rocket.  Will it still put Dragon 2 into orbit?  Maybe -- while F9-FT+ (the most recent tweak) has plenty of power to get Dragon 2 into orbit, a reduced prop load may not.  Or, it may, but without enough reserves to allow for first stage recovery.

Sorry, I'm not one of the experts, like Jim or Lou, but those seem to me to be the logical possibilities...

[Brovane]

We are getting off track from the original question. 

Can the latest version of the F9 launch without using densified propellant?  I am not really interested in debating about whether our not the astronauts should board before after our before propellant loading.

Gut response -- maybe, but possibly not at all.

First off, the prop loading setup now deep-chills both LOX and RP-1.  Is it possible to bypass the deep coolers at this point?  Depending on how they are installed, perhaps not.  I seriously doubt it's as simple as "well, just turn off the refrigeration."

It could be just as simple as turning off the Nitrogen subcooler.  Since it is just a heat-exchanger, you just let the propellant run through the heat exchanger without cooling it any further. 

Second, the turbopumps, pressurization systems, etc., have now been optimized for the deep-chilled propellants.  Will everything work fine without the deep cooling?  Maybe, but possibly not.

From what I understand the Merlin 1D engines on the F9v1.1 on the latest version of the F9 are essentially the same engines, just the engine is passing more propellant to support the greater thrust.  The Merlin Vacuum on the 2nd stage also has a bigger engine bell. 

Finally, the main reason for propellant densification via deep-cooling was, and is, to be able to load more prop on the bird.  With less prop, you get less total energy out of your rocket.  Will it still put Dragon 2 into orbit?  Maybe -- while F9-FT+ (the most recent tweak) has plenty of power to get Dragon 2 into orbit, a reduced prop load may not.  Or, it may, but without enough reserves to allow for first stage recovery.

Sorry, I'm not one of the experts, like Jim or Lou, but those seem to me to be the logical possibilities...

The 1st stage for the F9FT has a smaller LOX tank and a larger RP1 than the V1.1 since LOX can be made more dense.  I would hazard to guess that even with a smaller fuel load without densification that you would see maybe a 20% payload drop to LEO which would rule out a RTLS but would still allow a drone ship landing. 

[the_other_Doug]

Good points.  But, let's cut to the chase...

If what we're really talking about is whether or not using super-cooled LOX and RP-1 mandates fueling after the crew is on board during a crewed Dragon launch, then let's look at the impact of loading props and then loading crew.

First off, SpaceX is reportedly working on procedures that let them sit through extended pad holds and maintain the super-cooled props, so there may not even be a question as to whether or not you would have time after prop loading to load the crew.  This will sort itself out over the RTF process, I imagine -- especially if anything about these new procedures contributed to the loss of the AMOS-6 launcher.  So, this might not prove to be the timing problem you might expect in re using super-cooled props.

But even then, let's say we are looking at avoiding problems that may occur during prop loading, and you don't want your crew on the spacecraft at the time when the AMOS-6 anomaly occurred.  Fine, let's look at it.

As it stands now, there is no pad crew near the launcher during prop loading.  If an incident occurs at this point in launch prep, the closest humans are a couple of miles away.  To maintain this safety factor and still load props before crew, you would need to:

1.  Evacuate the pad

2.  Load props

3.  Verify, to the best of your ability, the stability of the loaded vehicle

4.  Bring the crew and the white room personnel back to the pad

5.  Load the crew

6.  Perform final onboard launch readiness checks while support personnel evacuate

7.  Launch

I submit that the prop-loaded vehicle is intrinsically more dangerous to be working around, and that steps 4 and 5 expose white room workers, and anyone else who needs to be on or around the pad until after the crew is loaded and the white room is closed out, to a significantly greater risk than if prop is loaded after crew load.

The crew is intrinsically more safe, in that their LAS can be armed and ready from the beginning of prop load, if they are in the vehicle during prop load.  If an incident occurs in step 4 or 5 above for a post-prop-load crew ingress, the crew is not sealed inside the spacecraft, with an active escape option.  I submit this makes the crew actively safer, not to mention the white room crew, et. al., if prop loading happens after crew loading.

And as we saw last week, if something goes south on one of these boosters, it will likely not give you time to run to a slidewire... 

[Brovane]

I submit that the prop-loaded vehicle is intrinsically more dangerous to be working around, and that steps 4 and 5 expose white room workers, and anyone else who needs to be on or around the pad until after the crew is loaded and the white room is closed out, to a significantly greater risk than if prop is loaded after crew load.

The crew is intrinsically more safe, in that their LAS can be armed and ready from the beginning of prop load, if they are in the vehicle during prop load.  If an incident occurs in step 4 or 5 above for a post-prop-load crew ingress, the crew is not sealed inside the spacecraft, with an active escape option.  I submit this makes the crew actively safer, not to mention the white room crew, et. al., if prop loading happens after crew loading.

And as we saw last week, if something goes south on one of these boosters, it will likely not give you time to run to a slidewire... 

I don't disagree, but does it really matter what we think?  No it doesn't.  What matters is what the NASA wants and if NASA thinks that it is safer to load propellant before the astronauts board the spacecraft then that is what they are going to push for.  I have a feeling, the anomaly last week isn't going to make NASA feel any safer about propellant loading with the crew on-board. 

So if NASA insists on propellant loading being done before the crew board, were does that leave SpaceX and the Commercial Crew contract?  I have a feeling that their has to be a option for SpaceX to do propellant loading before the crew boards.  I wouldn't think that NASA would insist on something from SpaceX that they cannot technically do and SpaceX wouldn't put themselves in a corner with no options by designing the latest version of the F9 so it can only use densified propellant.  However you never know. 

[Lar]

I would expect SpaceX to just say no. They have good reason for the order they want to do it in.

[Brovane]

I would expect SpaceX to just say no. They have good reason for the order they want to do it in.

I would expect that NASA also has a good reason for the order they want it in also.  Who has more experience with manned space launch, NASA or SpaceX?  If SpaceX say's no, can NASA cancel the commercial crew contract with SpaceX and go down to one provider?  I wouldn't expect that NASA would not get much push back from Congress if they made this decision.  Even If if meant more money for Soyuz seats. 

"Yes Mr. Congressmen, we felt that SpaceX was insisting on implementing un-safe manned launch procedures based on our 5+ decades of experience.  We couldn't come to a resolution and we felt it was best to cancel the contract with SpaceX and go down to one provider.  We are not going to expose NASA astronauts to a un-safe launch system." 

You would then see a bunch of heads nodding on the Science and technology panel. 

SpaceX and NASA are heavily entwined and SpaceX needs be on NASA's good side if they are going to Mars.  If NASA wanted to they could make SpaceX's life very difficult for any of their plans for BEO exploration.  SpaceX cannot afford to make NASA upset by just saying No.  That isn't a good way to keep your #1 customer business.  Especially if you are wanting to use their communication network to land a Dragon on Mars. 

[A_M_Swallow]

SpaceX can now run simulations/games of the two loading people and propellant scenarios with NASA's safety people and ask the question "Which one leads to the fewest deaths with this accident?"

Allow time for the bureaucracy to make up its mind.

[Prober]

However I suspect that after this latest incident, NASA is going to have even more reason to want the crew loaded after the propellant and NASA is the customer.   

I think the reaction to this event will be the opposite. All the evidence we have (including Elon Musk's comments on twitter) indicate that Crew Dragon would have gotten away and this explosion was pretty fast.

To your other point, I don't think SpaceX is going away from densified propellents. It factors to heavily in to their reusability plans. So, NASA will work with SpaceX on it until they are happy. However, I don't see NASA forcing SpaceX to go away from densified propellents.

We are getting off track from the original question.

Can the latest version of the F9 launch without using densified propellant?  I am not really interested in debating about whether our not the astronauts should board before after our before propellant loading.

Who is the customer, and what is the real mission objective?


Remember a short time ago the F9 was made up of two models one disposable and one recoverable.   The secondary mission (recovery) isn't necessarily for the main mission is it?

[Brovane]

Who is the customer, and what is the real mission objective?


Remember a short time ago the F9 was made up of two models one disposable and one recoverable.   The secondary mission (recovery) isn't necessarily for the main mission is it?

The customer is NASA for Commercial Crew launches. 

Assumptions

NASA doesn't want propellant load started while astronauts are on-board the Dragon (Topping off is fine).   

Because of propellant densification SpaceX cannot support loading of the astronauts after the propellant load is completed. 

[eric z]

 Now that I'm somehow a "Full Member", and very proud of the honor!, could I ask a dumb question? Isn't it really late in the game for NASA and SpaceX to be unsettled about stuff like this?

[yg1968]

McAlister didn't make a big deal about densified propellant. He just said that NASA needed more data to get confortable with it.

Same thing goes for land landings. Incidentally, we don't know that NASA mandated water landing. We just know that SpaceX decided to go with water landings at first. We speculate that this is because of NASA's relaunctance with propulsive landing (without more data on it) but we don't know that for a fact.

[woods170]

More delays:

The Commercial Crew Program continues to face multiple challenges that will likely delay the first routine flight carrying NASA astronauts to the ISS until late 2018 – more than 3 years after NASA’s original 2015 goal. While past funding shortfalls have contributed to the delay, technical challenges with the contractors’ spacecraft designs are now driving the schedule slippages. For Boeing, these include issues relating to the effects of vibrations generated during launch and challenges regarding vehicle mass. For SpaceX, delays resulted from a change in capsule design to enable a water-based rather than ground-based landing and related concerns about the capsule taking on excessive water.

https://oig.nasa.gov/audits/reports/FY16/IG-16-028.pdf

And the delayed write-up by SN: http://spacenews.com/report-warns-of-additional-commercial-crew-delays/

By the sound of it is primarily the NASA mandated switch to ocean landings that is causing much trouble for SpaceX. It is what drove the addition of a fourth parachute and the associated additional drop testing, as well as having a lot of components changed to withstand a (sustained) wet landing.

[rayleighscatter]

More delays:

The Commercial Crew Program continues to face multiple challenges that will likely delay the first routine flight carrying NASA astronauts to the ISS until late 2018 – more than 3 years after NASA’s original 2015 goal. While past funding shortfalls have contributed to the delay, technical challenges with the contractors’ spacecraft designs are now driving the schedule slippages. For Boeing, these include issues relating to the effects of vibrations generated during launch and challenges regarding vehicle mass. For SpaceX, delays resulted from a change in capsule design to enable a water-based rather than ground-based landing and related concerns about the capsule taking on excessive water.

https://oig.nasa.gov/audits/reports/FY16/IG-16-028.pdf

And the delayed write-up by SN: http://spacenews.com/report-warns-of-additional-commercial-crew-delays/

By the sound of it is primarily the NASA mandated switch to ocean landings that is causing much trouble for SpaceX. It is what drove the addition of a fourth parachute and the associated additional drop testing, as well as having a lot of components changed to withstand a (sustained) wet landing.

Nothing mandated about it. SpaceX's aborts always assumed ocean landing.

[GalacticIntruder]

Landing in the ocean for an extremely rare emergency is not the same as nominal landings that SpX assumed would be on land. And SpaceX wants to reuse as much of the craft possible, if not the whole thing. Salt Water adds to the problems for that, and creates more issues. And the ocean logistics are added costs.  Imagine how easier life would be if they were allowed to land at CC, KSC, or even SSA.

[rayleighscatter]

Landing in the ocean for an extremely rare emergency is not the same as nominal landings.

Yes, but they still have to be adequately addressed.

It means safe water landings are a necessity for the system while land landings are a luxury. Safety will always drive schedule ahead of savings.