Author Topic: ASAP still has concerns over Commercial Crew LOC risks  (Read 6469 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.

 

Offline 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.

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.

Offline 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.


Offline 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.

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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Online 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.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

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.

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.

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.

Online 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.
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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... :)
-Doug  (With my shield, not yet upon it)

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