Author Topic: ASAP still has concerns over Commercial Crew LOC risks  (Read 18063 times)

Online Chris Bergin

It's your friendly ASAP sticking their nose in again :)

Interesting, all the same. Used some Nathan L2 renders, of course, to make the article sexier.

https://www.nasaspaceflight.com/2017/08/asap-concerns-commercial-crew-loc-risks/

Pardon me if this has already been discussed. However,  I would be interested to know how Soyuz scores based on the same criteria.

Offline whitelancer64

Pardon me if this has already been discussed. However,  I would be interested to know how Soyuz scores based on the same criteria.

I found a brief mention in the 2005 ESAS

https://www.nasa.gov/pdf/140639main_ESAS_08.pdf

Which gives the Soyuz LOC risk as 0.3%, or 1 in 333, and 0.5%, or 1 in 200, but these numbers are in a comparative chart, it does not explain how they arrived at the risk numbers.
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Offline woods170

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #3 on: 08/23/2017 06:50 PM »
It's your friendly ASAP sticking their nose in again :)

Interesting, all the same. Used some Nathan L2 renders, of course, to make the article sexier.

https://www.nasaspaceflight.com/2017/08/asap-concerns-commercial-crew-loc-risks/
Well I have to admit: they are consistent...


...in being boring as h*ll.

It's the same old tune being played over-and-over-and-over again.

Offline jkumpire

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #4 on: 08/23/2017 07:08 PM »
If these guys were around when Mercury was constructed and launched we wouldn't  be in space yet, or at best flying the 1035th M/R mission while the Atlas-E or Atlas V or Atlas QQ would be working on their 5000th qualification flight. NASA would be out of test monkeys, dogs, cats, gators, snakes, and raccoons.

 

Online Coastal Ron

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #5 on: 08/23/2017 07:31 PM »
From the article, and just so we more directly discuss/debate the issues:
Quote
The ASAP was presented with the three main “programmatic and safety risks” currently challenging the CCP, noted as the:

A. “inability to meet Loss of Crew (LOC) metrics
B. DoD’s Search and Rescue posture and capability
C. the possibility of aborts taking place in sea states that would be unsafe for rescue.”


It would seem to me that "B & C" might be easier to quantify and address, although both are contingent on weather and sea conditions that could change from moment to moment, which would be unpredictable.

For "A", in the article it says:
Quote
That was acknowledged by another ASAP panel member, who noted “One of the things the Panel has begun to observe and discuss is the considerable statistical distribution between the probabilities that are used in the model. As an example, one of the current calculations uses a value of 1:300 as a calculation for overall risk, but statistically, that number can vary between 1:140 and 1:1200.

This seems to be the biggest unresolved issue, is how this portion of risk is both quantified and calculated. Whereas "B & C" could be solved by training and launch timing, "A" seems to be directly related to spacecraft design and how well they can handle collisions and damage.

And at this point in the Commercial Crew program I would imagine it's too late to start adding layers of additional protection, like armor or active protection systems, so I would imagine that ASAP will end up stating that they are not happy about the levels of protection, but that they won't make too big of a fuss about it. And while we all want to have safe space transportation systems, risk has to be assumed - as it should be for any transportation system that is still, even after 50 years, in it's early days of maturity.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline duh

Are there numerical breakouts of how much of the risk is associated with each of the areas of concern?
For instance, what is the risk of MMOD causing LOC? or the sea state being unacceptable?

Pie in the sky (pun intended!) idea: Fly an extra Dragon unmanned as an on-orbit spare AND also
have an extra Dragon (or Starliner, or whatever) available on the ground for an rapid emergency
response, If the is MMOD damage, the assumption (hopefully valid) is that inspection on orbit would
preclude using a damaged spacecraft.

Another possibility would be to launch with maximum crew size of 3 but under emergency conditions
provide a means to reconfigure a second spacecraft to carry 6 people.

As for the sea state concern during ascent, how much more difficult would this be than having the
need to a trans-atlantic abort site during the shuttle era? Rephrasing the point, how much would be
probability of meeting launch commit criteria be lowered if the sea state was added to the rather
large list of constraints that already exists.

Just a thought or two to encourage discussion

Offline Jim

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #7 on: 08/23/2017 08:15 PM »

As for the sea state concern during ascent, how much more difficult would this be than having the
need to a trans-atlantic abort site during the shuttle era?

A TAL site has only a few people, a ship in the Atlantic has many times more


 Rephrasing the point, how much would be
probability of meeting launch commit criteria be lowered if the sea state was added to the rather
large list of constraints that already exists.


It already is for the barge and it was also for other manned capsule missions.

Offline john smith 19

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #8 on: 08/23/2017 09:38 PM »

As for the sea state concern during ascent, how much more difficult would this be than having the
need to a trans-atlantic abort site during the shuttle era?

A TAL site has only a few people, a ship in the Atlantic has many times more


 Rephrasing the point, how much would be
probability of meeting launch commit criteria be lowered if the sea state was added to the rather
large list of constraints that already exists.


It already is for the barge and it was also for other manned capsule missions.
That appears to be a logical contradiction.  :(

If sea state is already a launch constraint and the launch is scrubbed if it's too bad then the only way this is a LOC/LOM issue is if a)Launch goes ahead (IE Sea State acceptable then b) something goes wrong with booster but c)Sea State has worsened in the time between takeoff and capsule emergency landing.

What is that? 15-30 mins? With satellite surveillance of the whole launch and abort zone?

Am I missing something here? Is the timescale wrong? This only seems a credible scenario if Mission Control has failed to launch at least one time already and the person in charge says "We've got a 30 minute weather window and I'm feeling lucky so let's get this done" and it all goes wrong.   :(

This is a plot for an SF thriller.  :( It's completely non sensical IRL.

NASA would have be to extraordinarily desperate to behave in such a reckless fashion, and if they did safety concerns are pretty much out the window anyway.  :(

I do think its interesting that this is saying that the #1 mission and crew ending risk in LEO is micrometeroid damage.

So given that, what NASA programmes are targeting the reduction of this (some level of which is man made, but I don't know how much) ?

You'd think, given they are saying it could stop a multi $Bn mission in its tracks and/or take the lives of multiple astronauts that would be right at the top of the to-do list, because y'know "the safety of our astronauts is our highest priority."
« Last Edit: 08/23/2017 09:40 PM by john smith 19 »
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Offline A_M_Swallow

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #9 on: 08/23/2017 09:53 PM »
Sea state can effect re-entry. Although if the capsule can wait an extra 45 minutes it can fly from the Pacific to the Atlantic.

Offline Brovane

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #10 on: 08/23/2017 09:59 PM »
So what happened to all the "hand-wringing" over SpaceX planning to fuel the F9 while the astronauts are on board?  I am just surprised considering all the back and forth about this proposed practice after the AMOS-6 anomaly that the article makes no mention of it being a current concern for ASAP. 
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Offline john smith 19

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #11 on: 08/23/2017 10:46 PM »
Sea state can effect re-entry. Although if the capsule can wait an extra 45 minutes it can fly from the Pacific to the Atlantic.
But that's not a launch abort scenario.  :(

So

a) the capsule has to separate from the ISS and deorbit without delay and has to land in a non ideal sea state.

Or

b)it's separated already and it's been on orbit awaiting re-entry so long that the sea state has changed, again to a radically worse one.

a) This could be due to a catastrophic failure of the ISS, but if that were true once safety separated there should be enough time to await a safe landing zone. To give you a hard time limit and force a landing in worst case sea state conditions you'd need something like an imminent massive solar storm, forcing near immediate re-entry to have any hope of surviving.

Except by this point you're so far away from standard operating procedures any safety calculations have to be viewed as out the window. :( 

b) Seems even less likely.
AFAIK storm in the primary landing zone --> scrub landing. Again you'd have to have some really compelling (IE Life or death) reason not to stay on station a day or two longer and just sit the storm out.  :(

But this scenario seems to need 2 faults. The primary LZ is OK (so separation from Station is normal) but something fails and the capsule goes to a secondary with bad sea state, because Landing Commit Criteria
(and I'm quite sure NASA has a set) are not as strict as launch commit criteria.

Really?

IIRC Shuttle takeoffs and landings were scrubbed if any of the landing sites had poor weather on them.

IOW so much has to have gone wrong already that the chances of the crew surviving are already seriously reduced anyway.  :(

I would also ask is there in fact any design of capsule that can survive the stated sea states they are concerned about? IOW are they saying they don't like any capsule, or just the way these have been designed?

This ASAP complaint. It doesn't seem to make sense, but I'm not sure why.  :(
« Last Edit: 08/23/2017 10:57 PM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline Hauerg

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #12 on: 08/23/2017 11:12 PM »
Pardon me if this has already been discussed. However,  I would be interested to know how Soyuz scores based on the same criteria.

I found a brief mention in the 2005 ESAS

https://www.nasa.gov/pdf/140639main_ESAS_08.pdf

Which gives the Soyuz LOC risk as 0.3%, or 1 in 333, and 0.5%, or 1 in 200, but these numbers are in a comparative chart, it does not explain how they arrived at the risk numbers.
No idea: But STS had 1 in 50, so 2%. Seems NASA wS OK with that.

Online Coastal Ron

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #13 on: 08/23/2017 11:42 PM »
So what happened to all the "hand-wringing" over SpaceX planning to fuel the F9 while the astronauts are on board?  I am just surprised considering all the back and forth about this proposed practice after the AMOS-6 anomaly that the article makes no mention of it being a current concern for ASAP.

I'm not sure we can assume it's still not a concern for NASA, but yeah, no mention by the ASAP is sure interesting.

Maybe we won't get positive confirmation about this topic until NASA is done with their review of Block 5? And can we assume that SpaceX is still planning to load crew first and fuel second? Or is it possible that SpaceX decided to do-it-how-it's-always-been-done and fuel first and load crew second?

Inquiring minds want to know!
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline UltraViolet9

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #14 on: 08/24/2017 12:28 AM »

A little off topic, but related...

Was there any ASAP discussion about the 1-in-75 LOC for SLS/Orion?

Relative to CC 1-in-270 LOC goal and 1-in-150 LOC threshold?

Relative to STS 1-in-90 projected LOC at program end? 

Relative to STS 1-in-67 demonstrated LOC?

Thanks for any insights.


Online ulm_atms

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #15 on: 08/24/2017 12:30 AM »
No idea: But STS had 1 in 50, so 2%. Seems NASA wS OK with that.

I think NASA was more in the "No Choice" category.  The shuttle had many design pieces that naturally lowered the LOC ratio.  (Fragile tiles, SRMs that can't be shut down once lit, seams in the TPS for the landing gears, etc.)  A capsule is inherently simpler and safer then the shuttle could ever be.  With the current LOC ratio they want, the shuttle would of never flown.  And remember, the LOC ratio they are shooting for wasn't a specific, science evaluated type number...they basically took the shuttle's (which they SAY was 1:90 but in reality was 1:50) and basically said "Lets triple that and be triple safe!!" and that was it.  The fact that they want something safer then has ever been done to date, but then have seemingly conflicting ways of calculating the LOC ratio in the first place, it is no wonder they are having a hard time reaching it...it was all kinda arbitrary to begin with in my opinion.

Offline Steven Pietrobon

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #16 on: 08/24/2017 05:58 AM »
The article is saying the LOC is higher for on-orbit than during launch landing. That seems counter intuitive to me. The huge ISS has been up there for nearly 19 years without taking any major hits for debris. Historically, LOC has occurred during launch and entry.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline woods170

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #17 on: 08/24/2017 06:04 AM »
The article is saying the LOC is higher for on-orbit than during launch landing. That seems counter intuitive to me. The huge ISS has been up there for nearly 19 years without taking any major hits for debris. Historically, LOC has occurred during launch and entry.
The ISS is mostly armored with whipple shields and Kevlar linings to deal with the MMOD. The CCP ships don't have that level of MMOD protection. Their MMOD protection is much better than that of Soyuz, but substantially less than that of the ISS.

But you don't hear ASAP complaining over the lack of MMOD protection of Soyuz. Simply because there currently is no alternative to Soyuz.
ASAP d*mn well knows that even suggesting to stop US HSF, until a "safe" spacecraft is available, is a non-starter.
So they keep whining about the inability of the CCP providers to meet arbitrarily set LOC/LOM numbers. But that has led to protracted efforts to meet those arbitrary LOC/LOM numbers. Which is silly given that the current LOC/LOM figures for the CCP ships are already well above those of Soyuz. So what you have here is ASAP directly contributing to a continuation of a less-safe situation for US HSF by having the introduction of the CCP ships delayed over some arbitrary LOC/LOM numbers.

And that is the prime reason why I really don't like the way in which ASAP operates.
« Last Edit: 08/24/2017 06:21 AM by woods170 »

Offline Rocket Science

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #18 on: 08/24/2017 12:33 PM »
All this had wringing would magically go away if Orion/SLS was the only US system of choice available to fly to ISS...
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Offline tdperk

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #19 on: 08/24/2017 01:09 PM »
All this had wringing would magically go away if Orion/SLS was the only US system of choice available to fly to ISS...

I have no reason to doubt it.


...it was all kinda arbitrary to begin with in my opinion.

Give that man a kewpie doll!
« Last Edit: 08/24/2017 01:19 PM by tdperk »

Offline whitelancer64

The article is saying the LOC is higher for on-orbit than during launch landing. That seems counter intuitive to me. The huge ISS has been up there for nearly 19 years without taking any major hits for debris. Historically, LOC has occurred during launch and entry.

Define "major hits."

The ISS has a couple of relatively big holes through its solar arrays and radiator panels, it's just luck that those MMOD impacts haven't done critical system damage. MMOD blankets have been replaced due to cumulative damage, and on spacewalks they now regularly do inspections for MMOD panels that may need to be replaced.
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Offline whitelancer64

*snip*

But you don't hear ASAP complaining over the lack of MMOD protection of Soyuz. Simply because there currently is no alternative to Soyuz.

*snip*

The Soyuz are covered with layers of thermal insulation with an outer MMOD protection layer.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Offline john smith 19

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #22 on: 08/24/2017 04:20 PM »
All this had wringing would magically go away if Orion/SLS was the only US system of choice available to fly to ISS...
Yes it would be interesting to know just how much better (?) Orion is in this regard, given all the TLC NASA has lavished on the design over so many many years.  :(

I tend to view any person, or group, by what goals they say are important to them, and then by what activities they prioritize to reach those goals.

ASAP is saying this is the #1 hazard for crew transport vehicles in LEO.
What is NASA doing to clean up what's already there?
That's what causing this.
Slowing down (or stopping) making more is good, but how can you sweep a large volume of near Earth space cheaply of the very large number of objects too small for radar (IIRC everything < 5cm is invisible to ground radar) but still big enough to do damage?
If "Aerospace Safety" is their key task (which it is) shouldn't that be a key long term investigation for them?
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline whitelancer64

All this had wringing would magically go away if Orion/SLS was the only US system of choice available to fly to ISS...
Yes it would be interesting to know just how much better (?) Orion is in this regard, given all the TLC NASA has lavished on the design over so many many years.  :(

I tend to view any person, or group, by what goals they say are important to them, and then by what activities they prioritize to reach those goals.

ASAP is saying this is the #1 hazard for crew transport vehicles in LEO.
What is NASA doing to clean up what's already there?
That's what causing this.
Slowing down (or stopping) making more is good, but how can you sweep a large volume of near Earth space cheaply of the very large number of objects too small for radar (IIRC everything < 5cm is invisible to ground radar) but still big enough to do damage?
If "Aerospace Safety" is their key task (which it is) shouldn't that be a key long term investigation for them?

There are multiple threads on orbital debris cleanup. e.g., https://forum.nasaspaceflight.com/index.php?topic=35812.0

NASA has been studying the orbital debris problem since the 70s, and there is an Orbital Debris Program Office (established 1979), which btw issues a quarterly newsletter that is fascinating to read, they date back to 1996.

https://orbitaldebris.jsc.nasa.gov/quarterly-news/newsletter.html
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Offline woods170

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #24 on: 08/24/2017 05:18 PM »
*snip*

But you don't hear ASAP complaining over the lack of MMOD protection of Soyuz. Simply because there currently is no alternative to Soyuz.

*snip*

The Soyuz are covered with layers of thermal insulation with an outer MMOD protection layer.
Yes, and the "stopping power" of that set-up on Soyuz is considerably less than that of the CCP ships and almost non-existent compared to the set-up used on the USOS modules of ISS.

Offline whitelancer64

*snip*

But you don't hear ASAP complaining over the lack of MMOD protection of Soyuz. Simply because there currently is no alternative to Soyuz.

*snip*

The Soyuz are covered with layers of thermal insulation with an outer MMOD protection layer.
Yes, and the "stopping power" of that set-up on Soyuz is considerably less than that of the CCP ships and almost non-existent compared to the set-up used on the USOS modules of ISS.

If you say so.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Offline deruch

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #26 on: 08/25/2017 01:17 AM »
From the article, and just so we more directly discuss/debate the issues:
Quote
The ASAP was presented with the three main “programmatic and safety risks” currently challenging the CCP, noted as the:

A. “inability to meet Loss of Crew (LOC) metrics
B. DoD’s Search and Rescue posture and capability
C. the possibility of aborts taking place in sea states that would be unsafe for rescue.”


It would seem to me that "B & C" might be easier to quantify and address, although both are contingent on weather and sea conditions that could change from moment to moment, which would be unpredictable.
B is about DoD budgets and basically the fact that the Navy isn't going to stage whole carrier fleets out on the launch track line because they don't have either the materiel or funding to support at that level while still accomplishing everything else they are tasked with doing.

C is just a restatement of the fact that there's pretty much no way for anyone to know the sea-state at every point along the potential abort track--with future forecasting far enough (for all such points) to allow for the delay of rescue assets to arrive on scene--such that they can guarantee an abort will land and stay in a sea that is safe for rescue.
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Offline A_M_Swallow

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #27 on: 08/25/2017 03:51 AM »
I hope ASAP realises it has already won. The Commercial Crew spacecraft need to be the best not perfect.

To win the safety championship the Dragon V2, CST-100 and Dream Chaser need to safety ratings better that the Apollo Command Module, Shuttle and Soyuz.

At this point it is better for ASAP to ensure the companies have not missed anything. No oxygen tanks that will short out and explode.

Online docmordrid

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #28 on: 08/25/2017 08:46 AM »
>
At this point it is better for ASAP to ensure the companies have not missed anything. No oxygen tanks that will short out and explode.

IMO, using solar power rather than fuel cells is a big safety step. Hopefully Kilopower will prove itself useful and up the ante for BEO.
« Last Edit: 08/25/2017 08:48 AM by docmordrid »
DM

Offline john smith 19

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #29 on: 08/26/2017 07:08 AM »
IMO, using solar power rather than fuel cells is a big safety step. Hopefully Kilopower will prove itself useful and up the ante for BEO.
Kilopower is still a ways from first ground test. I think it's got excellent prospects for use on future probes but its now the baseline for the Mars DRA because NASA already had a 40Kw nuclear reactor as one of their options.

I think it's a huge leap to consider it for human crewed BEO anytime soon.  :(
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline A_M_Swallow

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #30 on: 08/27/2017 01:19 AM »
IMO, using solar power rather than fuel cells is a big safety step. Hopefully Kilopower will prove itself useful and up the ante for BEO.
Kilopower is still a ways from first ground test. I think it's got excellent prospects for use on future probes but its now the baseline for the Mars DRA because NASA already had a 40Kw nuclear reactor as one of their options.

I think it's a huge leap to consider it for human crewed BEO anytime soon.  :(

Kilopower should be available when a Moon base or Moon vehicle needs power. A robotic Moon base away from the poles is likely to need power. This will allow ASAP to measure the reliability in a working environment.

Offline john smith 19

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #31 on: 08/27/2017 06:18 AM »
Kilopower should be available when a Moon base or Moon vehicle needs power. A robotic Moon base away from the poles is likely to need power. This will allow ASAP to measure the reliability in a working environment.
That sounds like a much more plausible near term use, outside of on board power for an ion thruster driven outer planet probe, like to Saturn or Uranus.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline SWGlassPit

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #32 on: 09/01/2017 06:26 PM »
*snip*

But you don't hear ASAP complaining over the lack of MMOD protection of Soyuz. Simply because there currently is no alternative to Soyuz.

*snip*

The Soyuz are covered with layers of thermal insulation with an outer MMOD protection layer.
Yes, and the "stopping power" of that set-up on Soyuz is considerably less than that of the CCP ships and almost non-existent compared to the set-up used on the USOS modules of ISS.

If you say so.

woods170 is correct on this.  It's better than it was -- it got upgraded from "terrifying" to "not all that great."

Offline Oli

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #33 on: 09/04/2017 01:06 PM »
woods170 is correct on this.  It's better than it was -- it got upgraded from "terrifying" to "not all that great."

Gravity has taught us that Soyuz can be bombarded with orbital debris and still survive reentry.  :)
« Last Edit: 09/04/2017 01:14 PM by Oli »

Offline RonM

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #34 on: 09/04/2017 03:48 PM »
woods170 is correct on this.  It's better than it was -- it got upgraded from "terrifying" to "not all that great."

Gravity has taught us that Soyuz can be bombarded with orbital debris and still survive reentry.  :)

That was a Shenzhou. Wonder if anyone in the west looked at Shenzhou's LOC risks. Of course, because of Congress we'll never have a Shenzhou dock with ISS.

Offline Welsh Dragon

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #35 on: 09/04/2017 06:32 PM »
Damnation upon both of you and all your offspring into eternity for making me remember that utter pile of bovine excrement after I'd just about successfully repressed it again, but it had both a Soyuz and Shenzou in it. The former gets pretty pelted as the ISS breaks up.

Offline savuporo

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #36 on: 09/04/2017 09:38 PM »
That was a Shenzhou. Wonder if anyone in the west looked at Shenzhou's LOC risks..

I'm gonna guess they are ahead of Soyuz simply by the virtue of not landing in Siberia and needing a TP-82 for protection from local fauna.
Orion - the first and only manned not-too-deep-space craft

Offline Patchouli

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #37 on: 09/05/2017 01:33 AM »
That was a Shenzhou. Wonder if anyone in the west looked at Shenzhou's LOC risks..

I'm gonna guess they are ahead of Soyuz simply by the virtue of not landing in Siberia and needing a TP-82 for protection from local fauna.

I think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.

Though a crewed version of Dream Chaser in theory should beat both of them as far as landing safety goes.

That was one one part of STS that actually had a good safety record.
« Last Edit: 09/05/2017 01:36 AM by Patchouli »

Offline Proponent

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #38 on: 09/05/2017 01:19 PM »
I dunno about that.  IIRC, there was a report on Shuttle risks that identified the one-shot, high-speed landing as one of the larger risks.  One flight touched down short of the runway.

Offline Rocket Science

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #39 on: 09/05/2017 03:24 PM »
I dunno about that.  IIRC, there was a report on Shuttle risks that identified the one-shot, high-speed landing as one of the larger risks.  One flight touched down short of the runway.
Atlantis landed 600' short of the threshold at Rodgers Dry Lake and KSC SLF has a 1000' underun so it was no big deal for a PIC with a test pilot background, just more added excitement... The fact that the underun is available is part of the landing margin factored in...
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Offline the_other_Doug

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #40 on: 09/05/2017 04:36 PM »
I think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.

Actually, Crew Dragon will have four parachutes.  But Apollo 15 did teach the lesson of having a one-chute-out safety margin... :)
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Offline ChrisWilson68

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #41 on: 09/30/2017 02:12 AM »
I think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.

Though a crewed version of Dream Chaser in theory should beat both of them as far as landing safety goes.

That was one one part of STS that actually had a good safety record.

I disagree.  To land on a runway you give up being able to do ballistic re-entry.  Star liner and Dragon can lose all active control and go balistic and they'll come down fine.  All they need is the parachutes to pop open in a single event.  Space planes need control surfaces and active control all the way down.  It's much more complexity, which means more things that can go wrong.

Dragon is the safest in concept because it has a backup for the parachutes -- it can fire its Super Dracos if the parachutes don't open for some reason.

Offline rayleighscatter

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #42 on: 09/30/2017 09:50 PM »
Capsules can lose active control if they're already on the correct reentry path. Otherwise it will orbit forever, reenter too steep, or skip and then reenter too steep.

Offline Nibb31

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #43 on: 09/30/2017 09:56 PM »
Capsules can lose active control if they're already on the correct reentry path. Otherwise it will orbit forever, reenter too steep, or skip and then reenter too steep.

That is true for any reentry vehicle regardless of shape.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #44 on: 11/07/2017 06:16 AM »
I think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.

Though a crewed version of Dream Chaser in theory should beat both of them as far as landing safety goes.

That was one one part of STS that actually had a good safety record.

I disagree.  To land on a runway you give up being able to do ballistic re-entry.  Star liner and Dragon can lose all active control and go balistic and they'll come down fine.  All they need is the parachutes to pop open in a single event.  Space planes need control surfaces and active control all the way down.  It's much more complexity, which means more things that can go wrong.

Dragon is the safest in concept because it has a backup for the parachutes -- it can fire its Super Dracos if the parachutes don't open for some reason.
I really hope they have added the software to do this. Just as CRS-7 dragon was lost due to lack of software to pop off nose cone it would be crap to loose a crew because parashutes failed despite having enough hydrazene in the tank for a landing.

Yes they have given up propulsive landing but only I think to the safety standard to do it every time. At the point of total parashutes failure who gives a darn what the chance of a safe propulsive landing is, it is their only hope!

Then again the chance of it firing when the parashutes are fine and shredding parashutes should be considered.


« Last Edit: 11/17/2017 11:09 AM by Chris Bergin »

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #45 on: 11/12/2017 05:40 PM »
FWIW, to increase mission LOC/LOM now ... fly mission. Analyze. Rework. Fly again.

Why this doesn't happen ... IMO ... too much works too well ... the flights are cheaper/quicker than a certain bigger capsule ... CC converges on provable safety limits ... there then is pressure to actually fly crews.

Once crews start flying on CC, then there's pressure on the bigger capsule to do same. But it can't for cost/reasons, so everyone gets used to CC flying crew and the bigger capsule not flying crew.

This ends up not helping the big capsule, even though it should (a means to prove elements of big capsule with crew).

Because Congress doesn't want CC to follow Soyuz, they want the "big capsule" to. And, they can always blame CC for not flying, because "its too unsafe". Circular.

add:

What if CRS finds booster reuse is effective and accepts for flights? Then likewise CC might arrive at the same conclusion. NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.

How might 20-30 CRS/CC flights ... benefit LOC/LOM assessment/improvement? How much of this could also feed back into big capsule refinement? Might even improve Soyuz.
« Last Edit: 11/12/2017 05:46 PM by Space Ghost 1962 »

Offline rayleighscatter

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #46 on: 11/12/2017 08:14 PM »

NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.

What mission requires 30 CRS flights?

As upset as everyone gets for trying to invent missions for Orion then there's obviously no need to do it for CC either.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #47 on: 11/12/2017 08:56 PM »

NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.

What mission requires 30 CRS flights?

As upset as everyone gets for trying to invent missions for Orion then there's obviously no need to do it for CC either.
Missed the point. And its CRS/CC flights, because the same configuration could be used for both. Duh.

The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.

Not static, ground determined analysis. Sorry if I was unclear.

Edited by Lar.
« Last Edit: 11/14/2017 10:04 AM by Lar »

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #48 on: 11/12/2017 09:01 PM »

NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.

What mission requires 30 CRS flights?

As upset as everyone gets for trying to invent missions for Orion then there's obviously no need to do it for CC either.

30 CRS flights would support multiple Moon landings. Using 5 tonne payloads it will take a while to construct a lunar base. At 40 tonnes payload to the Moon entire buildings can be delivered in one go.

Offline woods170

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #49 on: 11/13/2017 07:13 AM »

NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.

What mission requires 30 CRS flights?

As upset as everyone gets for trying to invent missions for Orion then there's obviously no need to do it for CC either.
Missed the point. And its CRS/CC flights, because the same configuration could be used for both. Duh.

The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.

Not static, ground determined analysis. Perhaps I need to resort to purple crayon to get my point across?  ::)
Your point is clear. Two little flaws though:
- There won't be 30 missions to inform crew safety, not even when you add Cargo Dragon v2 missions into the mix.
- Purely commercial, non-NASA missions, such as the planned circumlunar mission, do not inform crew safety because NASA insight into those will be almost non-existent.

Right now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.
« Last Edit: 11/13/2017 07:14 AM by woods170 »

Offline pathfinder_01

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #50 on: 11/13/2017 07:50 AM »


Because Congress doesn't want CC to follow Soyuz, they want the "big capsule" to. And, they can always blame CC for not flying, because "its too unsafe". Circular.

add:

What if CRS finds booster reuse is effective and accepts for flights? Then likewise CC might arrive at the same conclusion. NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.

How might 20-30 CRS/CC flights ... benefit LOC/LOM assessment/improvement? How much of this could also feed back into big capsule refinement? Might even improve Soyuz.

1.  This isn't a Congress problem. Congress wants SLS because it creates the most jobs. Orion less so. Therefore Orion development takes a back seat to SLS development. It isn't like Apollo and the early space race where no new rockets were developed specifically for Mercury and Gemini(as that would only delay things) and Apollo used the Saturn 1B(which was an upgrade of an existing rocket) for a number of test flights. This is an ASAP problem. If they were interested in improving the safety of Orion they could always fly some of them on Delta IV heavy but that would require development which would take even more budget(or reduce budget to SLS, therefore delay is the better Option).

2.  There would only be limited data from Commercial Crew that would be relevant to Orion or Soyuz as one system was in development before commercial crew and the other was operational long before. The Russians already have a much more relevant data set for Soyuz and it' successors.

3. As much as I would love a block buy of 20-30 flight this isn't a good reason.  20-30 flights would improve Dragon 2 and Starliner by finding the problems that only experience could sort out. They say little to nothing about Orion.
« Last Edit: 11/13/2017 07:56 AM by pathfinder_01 »

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #51 on: 11/13/2017 09:59 PM »
NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.
What mission requires 30 CRS flights?
The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.
Your point is clear. Two little flaws though:
- There won't be 30 missions to inform crew safety, not even when you add Cargo Dragon v2 missions into the mix.
- Purely commercial, non-NASA missions, such as the planned circumlunar mission, do not inform crew safety because NASA insight into those will be almost non-existent.
1. Builds on my point. We think of such vehicles as a limiting cost and so minimize to fewest use. Which caps are ability to reach ASAP's desired LOC. Past LV reuse, things get safer/cheap in net when we get to a fair fraction of 100. SX likely to reach hundreds of missions off of reuse, so we're likely to reach comparative numbers to Shuttle.
2. AF contracts require all launches to "inform" on LV performance. A similar means to inform on crew safety under appropriate convention (possible in US but not Europe given certain laws) could supply such, part of adventurer contract of carriage.

Am quite serious about means to achieve best provable crew vehicle LOC. Which is potentially transferable to other vehicles.

Quote
Right now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.
Yes we are both looking at the same thing. Beyond NASA. Where its just an occasional client.

BTW, there are many "NASA's" inside of NASA. True of other agencies/ministries. Some see this too.

Difference might be about where and how to achieve said "pivot". Perhaps as temporary conservator? Thus the above.

Offline rayleighscatter

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #52 on: 11/25/2017 01:56 PM »
NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.
What mission requires 30 CRS flights?
The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.
Your point is clear. Two little flaws though:
- There won't be 30 missions to inform crew safety, not even when you add Cargo Dragon v2 missions into the mix.
- Purely commercial, non-NASA missions, such as the planned circumlunar mission, do not inform crew safety because NASA insight into those will be almost non-existent.
1. Builds on my point. We think of such vehicles as a limiting cost and so minimize to fewest use. Which caps are ability to reach ASAP's desired LOC. Past LV reuse, things get safer/cheap in net when we get to a fair fraction of 100. SX likely to reach hundreds of missions off of reuse, so we're likely to reach comparative numbers to Shuttle.
2. AF contracts require all launches to "inform" on LV performance. A similar means to inform on crew safety under appropriate convention (possible in US but not Europe given certain laws) could supply such, part of adventurer contract of carriage.

Am quite serious about means to achieve best provable crew vehicle LOC. Which is potentially transferable to other vehicles.

Quote
Right now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.
Yes we are both looking at the same thing. Beyond NASA. Where its just an occasional client.

BTW, there are many "NASA's" inside of NASA. True of other agencies/ministries. Some see this too.

Difference might be about where and how to achieve said "pivot". Perhaps as temporary conservator? Thus the above.

So what you are proposing is that commercial providers surrender their technology and data to the public good? Because that proposal isn't compatible with the current proprietary nature. Unless the intent is to create a de-facto eternal duopoly.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #53 on: 11/26/2017 06:00 PM »
So what you are proposing is that commercial providers surrender their technology and data to the public good?
Would you please explain this otherwise irrational conclusion?

Referenced posts say nothing of the kind. Perhaps something else not visible, possibly emotional, is being triggered?

Honestly have no idea where this comes from in the above discussion and would like to know if substantive, because it entirely escapes me and frankly no I don't comment to annoy anyone here as that is my only conclusion as to meaning.

Quote
Because that proposal isn't compatible with the current proprietary nature. Unless the intent is to create a de-facto eternal duopoly.
When has anyone advocated that, please?

Don't get any of this. Asking for advice/help from others, as I'm completely at sea here - help!

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #54 on: 11/27/2017 07:33 PM »
...

Quote
Right now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.
Yes we are both looking at the same thing. Beyond NASA. Where its just an occasional client.
...

NASA is asking for one crew flight per year from each of its two providers.  Both GS and EM have said that the demand for tourist flights is surprisingly robust -- which easily translates to more than one flight per year.  Why is 'Beyond NASA' envisioned as so desolate?
« Last Edit: 11/27/2017 07:34 PM by AncientU »
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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #55 on: 11/27/2017 07:40 PM »
So what you are proposing is that commercial providers surrender their technology and data to the public good?
Would you please explain this otherwise irrational conclusion?

Referenced posts say nothing of the kind. Perhaps something else not visible, possibly emotional, is being triggered?

Honestly have no idea where this comes from in the above discussion and would like to know if substantive, because it entirely escapes me and frankly no I don't comment to annoy anyone here as that is my only conclusion as to meaning.

Quote
Because that proposal isn't compatible with the current proprietary nature. Unless the intent is to create a de-facto eternal duopoly.
When has anyone advocated that, please?

Don't get any of this. Asking for advice/help from others, as I'm completely at sea here - help!

Haven't a clue what is meant here...
"If we shared everything [we are working on] people would think we are insane!"
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Online Space Ghost 1962

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #56 on: 11/28/2017 12:30 AM »
Thank you. It's nice to get confirmation that it's not just me. Worry sometimes that I say something that is wrong in a way I don't anticipate.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #57 on: 12/28/2017 07:13 PM »
Ok, to simplify then:


The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.

How is this accomplished? Do other companies get access to the flight/machine data, or do all future contacts go to the same two companies because they're the only ones who have access to the data needed to improve safety.

Unless you have another thought in mind on how, say, Lockheed could benefit from SpaceX's proprietary heatshield designs and data.
« Last Edit: 12/28/2017 08:52 PM by rayleighscatter »

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #58 on: 12/28/2017 09:01 PM »
Ok, to dumb it down then:


The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.

How is this accomplished? Do other companies get access to the flight/machine data, or do all future contacts go to the same two companies because they're the only ones who have access to the data needed to improve safety.

Unless you have another thought in mind on how, say, Lockheed could benefit from SpaceX's proprietary heatshield designs and data.
Perhaps you are unaware of prior practice.

All past HSF vehicles "inform" on safety/"best practices". Apart from proprietary implementation "flight data". Various groups/agencies/institutions are issued study contracts to take mission flight data and issue a study to find/characterize specific risks. This is used by those including ASAP to feed back to vendors/providers what to look for in refining/qualifying HSF SC/components/subsystems for use. At least with earlier vehicles/modules.

So, there's this new snazzy thing called "Big data", where how this is communicated is in specific "non flight data" form that fits into everyone's models, to specifically address particular concerns. (It's cleverly done so you can't abstract performance data from it.)

It's a similar treatment to how other aerospace standards of practice are improved upon.

But no,  not letting everyone see each others "stuff", but learning from "incidents". Like with airlines/munitions.

Oh, and there are legal/contractual terms too. Not like the "bad old days".

Offline envy887

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #59 on: 01/17/2018 04:03 PM »
SpaceX's view on the prop loading and COVP issues, from Hans Koenigsmann's testimony

Quote
At SpaceX, every design and operation decision is driven by safety and reliability. SpaceX recognizes that
some proposed operating procedures for the crew transportation system differ from those on the Space
Shuttle Program. SpaceX has elected to adopt certain approaches, including propellant loading after
astronauts have been secured in the spacecraft and the launch escape system is enabled, because they offer
the potential to improve safety for both astronauts and ground crew. Under SpaceX’s operations plan, after
astronauts board the spacecraft, the ground crew will close out the vehicle and will leave the launch site.
Launch vehicle propellant loading will begin only after the escape system is armed. This approach ensures
that astronauts have escape capability during any time propellant is on the launch vehicle, and it does not
expose ground crew to unnecessary risk. Notably, the Space Shuttle continued loading liquid hydrogen for
three hours (“Space Shuttle Replenish” procedure) after astronauts were aboard; propellant loading on
Falcon 9 consumes approximately 30 minutes, reducing the time astronauts are exposed to loading
operations.

We have also worked closely with NASA to further enhance the robustness of our composite overwrapped
pressure vessels (COPVs) and to ensure NASA is comfortable with their performance in a variety of flight
environments. We are confident that this process is safe, and we are working closely with NASA to
complete the ongoing, rigorous analysis necessary to achieve certification.
https://democrats-science.house.gov/sites/democrats.science.house.gov/files/documents/Koenigsmann%20Testimony.pdf

Not sure I agree with this logic (as risk and exposure time are not necessarily directly correlated) but it sounds like SpaceX expects to certify this prop loading procedure.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #60 on: 01/17/2018 05:01 PM »
The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.
« Last Edit: 01/17/2018 05:07 PM by punder »

Offline mn

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #61 on: 01/17/2018 06:07 PM »
The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

I suspect this has been discussed many times here (I did read it here at least once before no idea which thread).

The process of loading can easily be considered more dangerous than after loading is complete. There is lots of things going on during loading, once you are done you are in a stable state.

(this has been argued back and forth, I'm not saying absolutely one way is right, but there is certainly enough doubt that you cannot say 'How???')

I suspect that historically there were more anomalies during loading than after loading and before launch (if there is even enough incidents to create a meaningful statistic).

Offline deruch

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #62 on: 01/17/2018 06:25 PM »
The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

Because the highest danger is during fueling.  It's a dynamic process both in terms of the propellants themselves flowing but also the vehicle hasn't reached thermal stasis.  The danger that something goes wrong and causes an accident is much higher during this period than that it is during the relatively static period of topping-off/replenishment.  So, that added risk has to be weighed against the lower risk of fewer man minutes of exposure to a loaded rocket.  Exactly which one turns out to have the true lower risk is dependent on the variables: number of astronauts and ground crew exposed, loading duration, etc.
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Offline envy887

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #63 on: 01/17/2018 06:42 PM »
The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

No rocket is pressurized for flight until the final seconds of countdown, as far as I know. So crew weren't working on a pressurized, fueled rocket with either Shuttle or Titan II. There is only head pressure at the bottom of the tanks from the weight of the propellant higher up, but no flight pressurants.

AMOS-6 is a pretty good example of why exposure time and risk are not correlated. The LOX tank and the COPVs were being filled, with pressures, fill levels, and temperatures constantly changing until they reached an unstable point that hadn't been reached before, resulting in the explosion.

Once filled, everything on a non-sub-cooled rocket is basically in steady state and can sit with occasional topping for boiloff for as long as you want with nothing really changing. This doesn't really work for a subcooled rocket.

SpaceX wants to make the process inherently safe and controlled. Every other type of vehicle is fueled with passengers and crew aboard. But they have a lot of work to do to prove that Falcon 9 is just as safe as other vehicles, since the fuels are inherently more dangerous.
« Last Edit: 01/17/2018 06:45 PM by envy887 »

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #64 on: 01/17/2018 07:06 PM »
Difficult to see how pad crew that have evacuated the pad, can be injured by a prop-loading mishap, when the prop-loading begins only after they have evacuated the pad.

So right there, the number of personnel exposed to danger has been halved or more than halved.

The remaining personnel still in danger--the flight crew--are sitting in a fully armed launch escape system that necessarily features, as part of its fundamental design, successful operation upon detection of a sudden, unanticipated booster explosion on the pad. Of course the LES doesn't eliminate the risk of LOC but without it, the LOC probability is 1.


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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #65 on: 01/17/2018 07:19 PM »
The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

No rocket is pressurized for flight until the final seconds of countdown, as far as I know. So crew weren't working on a pressurized, fueled rocket with either Shuttle or Titan II. There is only head pressure at the bottom of the tanks from the weight of the propellant higher up, but no flight pressurants.

AMOS-6 is a pretty good example of why exposure time and risk are not correlated. The LOX tank and the COPVs were being filled, with pressures, fill levels, and temperatures constantly changing until they reached an unstable point that hadn't been reached before, resulting in the explosion.

Once filled, everything on a non-sub-cooled rocket is basically in steady state and can sit with occasional topping for boiloff for as long as you want with nothing really changing. This doesn't really work for a subcooled rocket.

SpaceX wants to make the process inherently safe and controlled. Every other type of vehicle is fueled with passengers and crew aboard. But they have a lot of work to do to prove that Falcon 9 is just as safe as other vehicles, since the fuels are inherently more dangerous.

The Titan II fatalities occurred in operational silos where the Titans were fully fueled and capable of being brought to flight pressures within minutes.

http://www.themilitarystandard.com/missile/titan2/accident_374-7_1976.php
http://www.themilitarystandard.com/missile/titan2/littlerockaccident.php
http://www.themilitarystandard.com/missile/titan2/accident_533-7_1978.php


Offline Rocket Science

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #66 on: 01/17/2018 07:26 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o
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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #67 on: 01/17/2018 08:09 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o

Sorry if I'm annoying people. I just can't wrap my head around the idea that working around, riding an elevator beside, climbing into etc. an empty shell might be considered more dangerous than doing the same things when the empty shell has been transformed into a very large bomb.

Offline rayleighscatter

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #68 on: 01/17/2018 09:02 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o

Sorry if I'm annoying people. I just can't wrap my head around the idea that working around, riding an elevator beside, climbing into etc. an empty shell might be considered more dangerous than doing the same things when the empty shell has been transformed into a very large bomb.

It's statistical analysis.

It's the same reason it's fine for them to store large amounts of fuel and oxidizer on site for months and have people working around them, but why no extraneous personnel can be around when it's transferred from the trucks.
 

Offline Negan

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #69 on: 01/17/2018 09:24 PM »
The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

Sad part is SpaceX has already proved at least 38 times in a row they can safely fuel F9 without blowing it up, and that's with some flight-proven 1st stages in the mix.

Edit: Not to mention "returning helium loading operations to a prior flight proven configuration based on operations used in over 700 successful COPV loads"
« Last Edit: 01/17/2018 10:01 PM by Negan »

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #70 on: 01/17/2018 09:35 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o

Sorry if I'm annoying people. I just can't wrap my head around the idea that working around, riding an elevator beside, climbing into etc. an empty shell might be considered more dangerous than doing the same things when the empty shell has been transformed into a very large bomb.

It's statistical analysis.

It's the same reason it's fine for them to store large amounts of fuel and oxidizer on site for months and have people working around them, but why no extraneous personnel can be around when it's transferred from the trucks.

Must be a case of dueling statistical analyses.   :)

Offline Rocket Science

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #71 on: 01/17/2018 10:09 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o

Sorry if I'm annoying people. I just can't wrap my head around the idea that working around, riding an elevator beside, climbing into etc. an empty shell might be considered more dangerous than doing the same things when the empty shell has been transformed into a very large bomb.
Nah, it's all good... We have to pass the time until we "finally" get to launch crews from US soil again whoever goes first! :)
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Offline mn

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #72 on: 01/17/2018 11:01 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o

Sorry if I'm annoying people. I just can't wrap my head around the idea that working around, riding an elevator beside, climbing into etc. an empty shell might be considered more dangerous than doing the same things when the empty shell has been transformed into a very large bomb.

Nobody ever said that entering the empty vehicle was more dangerous, the danger is in the fueling process and the question is do you want the crew sitting there during that process.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #73 on: 01/17/2018 11:14 PM »
Loading prop after crew ingress increases the risk of a pad abort by some unknown amount. Loading prop before crew ingress might slightly increase the risk to flight and ground crew during ingress prior to LES activation. Which is safer depends on the probability of an emergency during prop load combined with the success rate of LES on pad aborts, as compared to the probability of an emergency during replenishment and the prospects for escaping such an emergency via the slidewires.

The risk of something going very wrong during replenishment should be significantly lower than the risk during prop load. But the odds of a successful escape should be significantly higher with the LES. It's not a straightforward comparison.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #74 on: 01/17/2018 11:25 PM »
Wow this thread is like Deja vu all over again from AMOS-6... :o

Sorry if I'm annoying people. I just can't wrap my head around the idea that working around, riding an elevator beside, climbing into etc. an empty shell might be considered more dangerous than doing the same things when the empty shell has been transformed into a very large bomb.

Nobody ever said that entering the empty vehicle was more dangerous, the danger is in the fueling process and the question is do you want the crew sitting there during that process.

I see your point, but given a launch escape system, I'd say yes. Are you listening, NASA?   :D

I'm a train nut who gets nervous just standing next to old steam engines at 200 psi... they have occasionally launched their boilers into short but highly spectacular suborbital trajectories, with entirely predictable consequences for the unfortunate cab crew. (Sorry OT.)

Offline Jim

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #75 on: 01/17/2018 11:52 PM »

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

No, not in this exact scenario. For one accident, they were disconnecting a pressurization line and a quick disconnect did not work.    The other accident, a worker dropped a large socket that punctured the fuel tank.    Not the same as loading a crew.

Offline Steven Pietrobon

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #76 on: 01/18/2018 05:17 AM »
Sad part is SpaceX has already proved at least 38 times in a row they can safely fuel F9 without blowing it up, and that's with some flight-proven 1st stages in the mix.

That's 19 times in a row since the last fuelling explosion on 1 September 2016 with AMOS 6. Lets try and get some numbers. I made some engineering guestimates.

Probability vehicle fails after loading = p = 0.01 (an engineering guess upper bound)
Probability vehicle fails during loading = 2*p = 0.02 (this is twice more dangerous)
Probability escape vehicle fails = q = 0.1 (remember seeing this somewhere)
Probability fail to get away from vehicle during fuelling = 2*q = 0.2 (assume twice more dangerous)
Number of flight crew = n = 4
Number of ground crew = n = 4 (assume same as flight crew)
Assume time to load propellants is same as time to load crew (half an hour).

Expected loss standard procedure = 2*n*2*q*p = 4*n*p = 0.016
Expected loss SpaceX procedure = n*q*2*p = 0.008

What this shows is that the SpaceX procedure is safer because less people are exposed to risk and that the crew escape system is safer than having the ground and flight crew try and get away using slide wires. As the Space Shuttle did not have an escape system, the standard procedure is the safest way.
« Last Edit: 01/18/2018 05:18 AM by Steven Pietrobon »
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Offline watermod

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #77 on: 01/18/2018 05:40 AM »
So are the Dragon and the Starliner more dangerous for the astronauts to fly in then the Soyuz?    If not then NASA and the Congress should find other battles to quibble over.   If it is more dangerous than quibble away.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #78 on: 01/18/2018 05:43 AM »
So are the Dragon and the Starliner more dangerous for the astronauts to fly in then the Soyuz?

I would say yes as both of these vehicles are unproven.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline deruch

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #79 on: 01/18/2018 06:22 AM »
Sad part is SpaceX has already proved at least 38 times in a row they can safely fuel F9 without blowing it up, and that's with some flight-proven 1st stages in the mix.

That's 19 times in a row since the last fuelling explosion on 1 September 2016 with AMOS 6. Lets try and get some numbers. I made some engineering guestimates.

Probability vehicle fails after loading = p = 0.01 (an engineering guess upper bound)
Probability vehicle fails during loading = 2*p = 0.02 (this is twice more dangerous)
Probability escape vehicle fails = q = 0.1 (remember seeing this somewhere)
Probability fail to get away from vehicle during fuelling = 2*q = 0.2 (assume twice more dangerous)
Number of flight crew = n = 4
Number of ground crew = n = 4 (assume same as flight crew)
Assume time to load propellants is same as time to load crew (half an hour).

Expected loss standard procedure = 2*n*2*q*p = 4*n*p = 0.016
Expected loss SpaceX procedure = n*q*2*p = 0.008

What this shows is that the SpaceX procedure is safer because less people are exposed to risk and that the crew escape system is safer than having the ground and flight crew try and get away using slide wires. As the Space Shuttle did not have an escape system, the standard procedure is the safest way.

And how do your numbers work if the probability of failure during fueling is 5 or 10 or 20 times higher than the static condition or if ground crew numbers are larger/smaller?  That's the point.  The relative safety is highly dependent on the variables and as outsiders we don't have a good idea of how they are determined/supported.  SpaceX obviously thinks their procedures are safer, NASA may remain skeptical.  But, neither position is unreasonable from their respective positions.  It's only right that SpaceX believes in their processes (so long as they have the test data to back them up) and it's right for NASA to make them prove it.  The only no-nos are for SpaceX to stick to their method "just because" or for NASA to stubbornly reject it even in the face of good supporting data because it's NIH (not invented here; i.e. not the way we've always done it).
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Offline john smith 19

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #80 on: 01/18/2018 07:06 AM »

Expected loss standard procedure = 2*n*2*q*p = 4*n*p = 0.016
Expected loss SpaceX procedure = n*q*2*p = 0.008

What this shows is that the SpaceX procedure is safer because less people are exposed to risk and that the crew escape system is safer than having the ground and flight crew try and get away using slide wires. As the Space Shuttle did not have an escape system, the standard procedure is the safest way.
Which suggests (no proof, just suggests) that ASAP is thinking that programme vehicles don't have launch escape systems designed in, IE just like Shuttle.

This is simply bizarre, given they they know both capsules do (and DC will) and IIRC didn't they insist on them having such systems to begin with?

In aviation, loading passengers happens after the vehicle is fueled. This has (potentially) serious implications for ConOps with any future P2P BFS flights.
OTOH getting unstrapped from a capsule and running in a full pressure suit is a PITA.
However if you're in the same capsule with a finger poised over the Big Red Switch to fire the LES and watching any vehicle telemetry for anomalies that sounds quite a bit safer than being crew on the pad.

My instinct is go to the toilet, suit up and strap in then let the pad crew do their work, while being ready to punch out if anything looks off.
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Online rockets4life97

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #81 on: 01/18/2018 07:07 AM »
Sad part is SpaceX has already proved at least 38 times in a row they can safely fuel F9 without blowing it up, and that's with some flight-proven 1st stages in the mix.

That's 19 times in a row since the last fuelling explosion on 1 September 2016 with AMOS 6.

Negan is counting static fires. Should probably also count test fires at McGregor. So the number of successful fires with the current procedure is probably >50.

Offline deruch

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #82 on: 01/18/2018 08:20 AM »
Sad part is SpaceX has already proved at least 38 times in a row they can safely fuel F9 without blowing it up, and that's with some flight-proven 1st stages in the mix.

That's 19 times in a row since the last fuelling explosion on 1 September 2016 with AMOS 6.

Negan is counting static fires. Should probably also count test fires at McGregor. So the number of successful fires with the current procedure is probably >50.

That makes some assumptions that aren't necessarily supported though.  Firstly, McGregor firings are of each stage individually and not of a combined stack.  Seems like this shouldn't really be a factor, but maybe there is some unexpected difference.  Secondly, while I have a hard time believing that this would be so, IIRC, we don't actually know that the loading process at McGregor is exactly the same as at the launch pad.  Slightly more believable is that environmental factors could be a factor. 

With the static fires, we absolutely know that it is being done the same as on launch day.  So, while you're probably right that there have been more successful firings with the current procedure, I don't think we can yet say so definitively.
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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #83 on: 01/18/2018 08:29 AM »

Expected loss standard procedure = 2*n*2*q*p = 4*n*p = 0.016
Expected loss SpaceX procedure = n*q*2*p = 0.008

What this shows is that the SpaceX procedure is safer because less people are exposed to risk and that the crew escape system is safer than having the ground and flight crew try and get away using slide wires. As the Space Shuttle did not have an escape system, the standard procedure is the safest way.
Which suggests (no proof, just suggests) that ASAP is thinking that programme vehicles don't have launch escape systems designed in, IE just like Shuttle.

This is simply bizarre, given they they know both capsules do (and DC will) and IIRC didn't they insist on them having such systems to begin with?

In aviation, loading passengers happens after the vehicle is fueled. This has (potentially) serious implications for ConOps with any future P2P BFS flights.
OTOH getting unstrapped from a capsule and running in a full pressure suit is a PITA.
However if you're in the same capsule with a finger poised over the Big Red Switch to fire the LES and watching any vehicle telemetry for anomalies that sounds quite a bit safer than being crew on the pad.

My instinct is go to the toilet, suit up and strap in then let the pad crew do their work, while being ready to punch out if anything looks off.
John, passengers  have stayed boarded during refueling stops. If vapors are detected they can be asked to deplane...
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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #84 on: 01/18/2018 09:17 AM »
Because the highest danger is during fueling.  It's a dynamic process both in terms of the propellants themselves flowing but also the vehicle hasn't reached thermal stasis.  The danger that something goes wrong and causes an accident is much higher during this period than that it is during the relatively static period of topping-off/replenishment.  So, that added risk has to be weighed against the lower risk of fewer man minutes of exposure to a loaded rocket.  Exactly which one turns out to have the true lower risk is dependent on the variables: number of astronauts and ground crew exposed, loading duration, etc.

Emphasis mine.

"Relative" is the right word here. You see, there is nothing static about topping-off/replenishment:

- Valves are opening and closing, both on GSE and the launch vehicle. Propellant flow intermittently starts and stops, causing small, but significant rises and drops in propellant pressure in both GSE and the launch vehicle.
- Intermittent instances of venting, the result of a rise in tank-pressure. The venting results in a dropping tank-pressure. So, the tanks are constantly "breathing" which results in continues cycles of expanding/shrinking.
- People sometimes cite thermal equilibrium as the thing being "static". But that is not correct either. Temperature of parts of the launcher continue to drop well after topping-off/replenishment has started. The STS ET, for example, continued to "shrink" for almost an hour into the stable replenishment cycle because that first hour into the replenishment-cycle there was no thermal equilibrium.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #85 on: 01/18/2018 09:56 AM »
I wonder what ASAP had to say about fuel transfers to the ISS? And next fuel depots in space. Although a different environment it will become SOP (or has) one day with crew onboard.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #86 on: 01/18/2018 01:19 PM »
Sad part is SpaceX has already proved at least 38 times in a row they can safely fuel F9 without blowing it up, and that's with some flight-proven 1st stages in the mix.

That's 19 times in a row since the last fuelling explosion on 1 September 2016 with AMOS 6.

Negan is counting static fires. Should probably also count test fires at McGregor. So the number of successful fires with the current procedure is probably >50.

That makes some assumptions that aren't necessarily supported though.  Firstly, McGregor firings are of each stage individually and not of a combined stack.  Seems like this shouldn't really be a factor, but maybe there is some unexpected difference.  Secondly, while I have a hard time believing that this would be so, IIRC, we don't actually know that the loading process at McGregor is exactly the same as at the launch pad.  Slightly more believable is that environmental factors could be a factor. 

With the static fires, we absolutely know that it is being done the same as on launch day.  So, while you're probably right that there have been more successful firings with the current procedure, I don't think we can yet say so definitively.

Prop load during WDRs are also done the same as launch day, and Zuma did two of those and FH at least 1.

Seven Block 5 flights will be at least 42 stage loads (2x stages, 3x loads each counting McGregor), and probably >50 loads because each FH gets 12 stage loads, and Block 5 might get extra tests or WDRs.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #87 on: 01/18/2018 02:12 PM »
I don't like that NASA required SpaceX to remove the landing legs and go with water landings.  Yet Boeing can use air bags and do land landings.  Seems like a waste of innovation.

Does anyone think SpaceX will eventually go back to landing legs for non-NASA flights?

« Last Edit: 01/18/2018 02:13 PM by spacenut »

Offline kevinof

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #88 on: 01/18/2018 02:33 PM »
Nope. Dragon2 is not their end-game. BFR is where they want to be and why waste the money and time getting legs on a Dragon?

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #89 on: 01/18/2018 03:03 PM »
That's 19 times in a row since the last fuelling explosion on 1 September 2016 with AMOS 6.
Wrong, static fires fully fuel the vehicle, and every launch has been preceded by a static fire.  The originally cited 38 is correct.

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #90 on: 01/18/2018 03:08 PM »
As an aside, whatever risk there is in Astros needing to use the Boeing crew escape system (the slide wire) from the pad must be accounted for.  I would assume the estimated level of risk in using the system itself is generally considered to be low.  Presumably the window of time where it would be used is also low, as once the Astros are in the craft and buckled in, the LES should take over responsibility rather than using the slide wire.

Also worth noting that SpaceX has no equivalent system because of their plans to board unfueled.  If at some point those plans change, they will presumably have to implement a crew escape system similar to Boeing's.

Online Lar

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #91 on: 01/18/2018 03:44 PM »
As an aside, whatever risk there is in Astros needing to use the Boeing crew escape system (the slide wire) from the pad must be accounted for.  I would assume the estimated level of risk in using the system itself is generally considered to be low.  Presumably the window of time where it would be used is also low, as once the Astros are in the craft and buckled in, the LES should take over responsibility rather than using the slide wire.

Also worth noting that SpaceX has no equivalent system because of their plans to board unfueled.  If at some point those plans change, they will presumably have to implement a crew escape system similar to Boeing's.

Which will add delay. Which will be the fault of SpaceX even if NASA or congress mandates it.

SpaceX knew they wouldn't catch any breaks in taking on OldSpace...
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
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Online gongora

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #92 on: 01/18/2018 03:55 PM »
Also worth noting that SpaceX has no equivalent system because of their plans to board unfueled.  If at some point those plans change, they will presumably have to implement a crew escape system similar to Boeing's.

I thought SpaceX is also going to have a slide wire system on 39A?

Offline DigitalMan

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #93 on: 01/18/2018 04:03 PM »
Also worth noting that SpaceX has no equivalent system because of their plans to board unfueled.  If at some point those plans change, they will presumably have to implement a crew escape system similar to Boeing's.

I thought SpaceX is also going to have a slide wire system on 39A?

There already was a slide wire system.  I don’t know what state it was in but I can probably dig up pictures from just before 39A handover

Offline woods170

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #94 on: 01/18/2018 06:00 PM »
I wonder what ASAP had to say about fuel transfers to the ISS? And next fuel depots in space. Although a different environment it will become SOP (or has) one day with crew onboard.

ASAP has nothing to say about that, given that fuel transfer to the ISS is already happening, on a regular basis, on the Russian Segment. It was done on five (5) ATV missions and Progress freighters also regularly transfer fuel into the tanks of the Zvezda module.

Offline woods170

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Re: ASAP still has concerns over Commercial Crew LOC risks
« Reply #95 on: 01/18/2018 06:03 PM »
Also worth noting that SpaceX has no equivalent system because of their plans to board unfueled.  If at some point those plans change, they will presumably have to implement a crew escape system similar to Boeing's.

I thought SpaceX is also going to have a slide wire system on 39A?

That was the plan once. But plans may have changed when they switched to fueling after the crew has boarded. Don't know if the slide wires will still be there.

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