Author Topic: ASAP still has concerns over Commercial Crew LOC risks  (Read 6283 times)

Online 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.
"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 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
"There are lies, damned lies, and launch schedules." - Larry J

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.

Online 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
"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
"There are lies, damned lies, and launch schedules." - Larry J

Online 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.

Online 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
"There are lies, damned lies, and launch schedules." - Larry J

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.

Offline 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 »
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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 »

Online 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.

Online 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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