Author Topic: JSC Depot Presentation  (Read 9147 times)

Offline jongoff

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JSC Depot Presentation
« on: 04/23/2012 06:01 PM »
NASAWatch posted an interesting presentation today on propellant depot risk mitigation done at JSC last year:

http://nasawatch.com/archives/2012/04/nasa-still-thin.html

I find it interesting to note that the ISS data supports a catastrophic AR&D (autonomous rendezvous and docking) failure rate about 1000x lower probability than was used in HEFT or ESAS when analyzing propellant depot risks. I figured there was something wrong with assuming that AR&D was 10,000x riskier than an aircraft carrier landing...

~Jon

Offline Jason1701

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Re: JSC Depot Presentation
« Reply #1 on: 04/23/2012 09:34 PM »
Who can now say that NASA didn't have fingers on the scale for those studies? :)

Offline Eric Hedman

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Re: JSC Depot Presentation
« Reply #2 on: 04/23/2012 09:39 PM »
Saturday I asked Jim Sensenbrenner if the House Science Committee, which he is a member of, ever got the fuel depot report.  He said no.

Offline BrightLight

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Re: JSC Depot Presentation
« Reply #3 on: 04/23/2012 09:46 PM »
NASAWatch posted an interesting presentation today on propellant depot risk mitigation done at JSC last year:

http://nasawatch.com/archives/2012/04/nasa-still-thin.html

I find it interesting to note that the ISS data supports a catastrophic AR&D (autonomous rendezvous and docking) failure rate about 1000x lower probability than was used in HEFT or ESAS when analyzing propellant depot risks. I figured there was something wrong with assuming that AR&D was 10,000x riskier than an aircraft carrier landing...

~Jon
3 orders of magnitude difference, how do they sleep at night :'(

Offline jongoff

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Re: JSC Depot Presentation
« Reply #4 on: 04/23/2012 09:54 PM »
NASAWatch posted an interesting presentation today on propellant depot risk mitigation done at JSC last year:

http://nasawatch.com/archives/2012/04/nasa-still-thin.html

I find it interesting to note that the ISS data supports a catastrophic AR&D (autonomous rendezvous and docking) failure rate about 1000x lower probability than was used in HEFT or ESAS when analyzing propellant depot risks. I figured there was something wrong with assuming that AR&D was 10,000x riskier than an aircraft carrier landing...

~Jon
3 orders of magnitude difference, how do they sleep at night :'(

Maybe they're physicists?  I once heard a physicist say that +/- three orders or magnitude was pretty close for some things in physics...

But the correct answer to your question is "just fine, unfortunately."

~Jon
« Last Edit: 04/23/2012 09:54 PM by jongoff »

Offline jongoff

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Re: JSC Depot Presentation
« Reply #5 on: 04/23/2012 09:55 PM »
Who can now say that NASA didn't have fingers on the scale for those studies? :)

Well, that's been obvious for four or five years now...

The good news is that little by little the anti-depot arguments are being shown to be full of holes.

~Jon

Offline BrightLight

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Re: JSC Depot Presentation
« Reply #6 on: 04/23/2012 10:26 PM »
Hey Jongoff
I'm a physicist, and three orders of magnitude count over here big, and I mean being off by three orders gets one in big trouble  ;D

Online Space OurSoul

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Re: JSC Depot Presentation
« Reply #7 on: 04/23/2012 10:38 PM »
Do you think they were taking Progress' demonstrated rate at the time?

Even then, 1.5% would be about double the real rate now (if it's true that there was only ever that one fender-bender with MIR)

A complete OurSoul

Offline jongoff

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Re: JSC Depot Presentation
« Reply #8 on: 04/23/2012 10:42 PM »
Hey Jongoff
I'm a physicist, and three orders of magnitude count over here big, and I mean being off by three orders gets one in big trouble  ;D

I can't remember who said it (and if he was being tongue-in-cheek or serious), but I do remember the "wow, I'm apparently in the wrong profession" reaction he got.

~Jon

Offline BrightLight

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Re: JSC Depot Presentation
« Reply #9 on: 04/23/2012 10:47 PM »
Hey Jongoff
I'm a physicist, and three orders of magnitude count over here big, and I mean being off by three orders gets one in big trouble  ;D

I can't remember who said it (and if he was being tongue-in-cheek or serious), but I do remember the "wow, I'm apparently in the wrong profession" reaction he got.

~Jon
In astrophysics you can get away with 3 or 4 orders of magnitude, as opposed to terrestrial applied-theoretical work.  In back of the envelope calculations of probability of error or even incident, three orders of magnitude is borderline incompetent. They knew what they were doing, and the 1 MIR incident (I think it was MIR) might be for other reasons.

Offline QuantumG

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Re: JSC Depot Presentation
« Reply #10 on: 04/24/2012 12:04 AM »
Saturday I asked Jim Sensenbrenner if the House Science Committee, which he is a member of, ever got the fuel depot report.  He said no.

Why don't they just subpoena what they want?
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline muomega0

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Re: JSC Depot Presentation
« Reply #11 on: 04/24/2012 02:00 AM »
NASAWatch posted an interesting presentation today on propellant depot risk mitigation done at JSC last year:

http://nasawatch.com/archives/2012/04/nasa-still-thin.html

I find it interesting to note that the ISS data supports a catastrophic AR&D (autonomous rendezvous and docking) failure rate about 1000x lower probability than was used in HEFT or ESAS when analyzing propellant depot risks. I figured there was something wrong with assuming that AR&D was 10,000x riskier than an aircraft carrier landing...

~Jon

In the ESAS Risk Study, AR&D was 1 in 97 or about 1% (pg 575), and in the underfunded JSC study slightly higher at 1.5% (which may be orders of magnitude too high), but even at this level of failure note the conclusion:

Quote
"This {JSC depot} study does not support the perception that depots add an unacceptable amount of risk and and should not be considered due to an increased number of launches, AR&Ds, and transfers"

But return to ESAS
Quote
ESAS Risk pg 605
o "Mission modes requiring three launches were eventually eliminated from consideration due to their cost and reliability issues (i.e., multiple launches, AR&D)."

pg 575
o "The final lunar mission architecture selected does not require AR&D. Pressurized cargo delivery to the ISS will require some level of AR&D; however, ISS crew will be available to provide backup capability. Other lunar missions that were considered did use AR&D. In many of these missions, the risk presented from AR&D was a driver"

Note the statement on ISS cargo delivery.

Regardless, the conclusions from the underfunded JSC depot study and the ESAS risk study are quite contradictory.

The leaked NASA study on depots contradicts the cost rationale of all *HLV only* studies as well.

Offline Blackjax

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Re: JSC Depot Presentation
« Reply #12 on: 04/24/2012 02:27 AM »
Saturday I asked Jim Sensenbrenner if the House Science Committee, which he is a member of, ever got the fuel depot report.  He said no.

Why don't they just subpoena what they want?


I'm sure they'd subpoena what they *want*.  Why would they want this?  It would further undermine the case for a giant pork fueled rocket.  Congressional support for NASA efforts is not normally driven by an altruistic desire to yield the maximum amount of space and science results for a given amount of funding, it is driven by a desire to route funds to specific destinations.  The funding destinations involving a giant pork fueled rocket are apparently much higher on the priority list than those involving depot based architectures.

Offline QuantumG

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Re: JSC Depot Presentation
« Reply #13 on: 04/24/2012 03:50 AM »
I'm sure they'd subpoena what they *want*.  Why would they want this?

Good point, and to clean this up a bit.. the Chairman of the committee, and preferably also the ranking member, have to issue the subpoena.. so it is they who have to want it.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline Proponent

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Re: JSC Depot Presentation
« Reply #14 on: 04/24/2012 04:06 AM »
Saturday I asked Jim Sensenbrenner if the House Science Committee, which he is a member of, ever got the fuel depot report.  He said no.

Why don't they just subpoena what they want?


I'm sure they'd subpoena what they *want*.  Why would they want this?  It would further undermine the case for a giant pork fueled rocket.  Congressional support for NASA efforts is not normally driven by an altruistic desire to yield the maximum amount of space and science results for a given amount of funding, it is driven by a desire to route funds to specific destinations.  The funding destinations involving a giant pork fueled rocket are apparently much higher on the priority list than those involving depot based architectures.

It was Rep. Rohrabacher in particular who was pushing NASA for info about propellant depots.  During Administrator Bolden's March 7 appearance before the House Science, Space & Technology Committee, Rohrabacher mentioned a briefing related to depots that he'd received from Bolden the previous day.  Specifically, at 1:30:55, Rohrabacher says:

I want to thank Gen. Bolden for the fine briefing I had yesterday, and for the record, Mr. Chairman, I want to make sure that I again mention, and Rep. Fudge helped me bring up the issue of cryogenic propellant storage and transfer as a, really a vital technology.  And I was very satisfied with our conversation yesterday as to the importance of that technology, and recognition of that.

So it would seem that Rohrabacher has received some kind of assurance from Bolden about depots and is not likely to pursue a subpoena, despite his continued skepticism about SLS, per remarks at 1:35:49:

As you're fully aware, General, I am very concerned that we have committed ourselves to this new mega-rocket transportation system, which may, I think, siphon money away from other projects that are vital, and maintaining our reliability with our European partners is vital to the success of our future missions, and if we end up in order to build this big rocket that may or may not succeed ten years down the road, if we end up putting ourselves in jeopardy with these other type of things, whether it's, whether we're talking about co-operation or other type of projects that we need to do, then we haven't really done a good service for our whole space effort.  But I rely on your judgment....

Offline simonbp

Re: JSC Depot Presentation
« Reply #15 on: 04/24/2012 04:39 PM »
I find it interesting to note that the ISS data supports a catastrophic AR&D (autonomous rendezvous and docking) failure rate about 1000x lower probability than was used in HEFT or ESAS when analyzing propellant depot risks. I figured there was something wrong with assuming that AR&D was 10,000x riskier than an aircraft carrier landing...

To be fair, the US had only actually successfully done an AR&D once when ESAS was written, and the Progress crash into Mir was a fresh memory. No excuse for HEFT, though...

And the order of magnitude thing is really with astrophysics; we tend to get ridiculously unconstrained problems coupled with very complex models. Some parameters are very sensitive, but most simply aren't (or are degenerate with each other). So, you end up with a lot of "constraints" that range over a few orders of magnitude. It looks silly, but it's mathematically honest with the tiny amount of data you've got.

And I think something of that is going on with these numbers. There are so few cases of AR&D that you really can't put a statistically significant number on them. So, the one-sigma probability of failure probably ranges several orders of magnitude. An honest reporting would show that, but engineers, being ultra-conservative, choose the worst case out of that range and take it as gospel. Thus, everything looks terrifically unsafe until you've done it enough times for the statistics to converge.
« Last Edit: 04/24/2012 04:42 PM by simonbp »

Offline alexw

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Re: JSC Depot Presentation
« Reply #16 on: 04/25/2012 05:34 AM »
Fair points, Simon; however:

And I think something of that is going on with these numbers. There are so few cases of AR&D that you really can't put a statistically significant number on them. So, the one-sigma probability of failure probably ranges several orders of magnitude.
   Paging Ed et. al. ... paging Ed ...

   Ok, resorting to WP, I see: a claimed 138 Progress flights across Salyut 6, 7, MIR, and ISS. One lost at launch, one or two collisions under TORU with MIR (hence obviously not AR&D), and at least a couple successful TORU dockings.
   So, we have something like n ~ 130?  Hardly worthless for statistical significance.
     -Alex

Offline oldAtlas_Eguy

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Re: JSC Depot Presentation
« Reply #17 on: 05/01/2012 04:18 PM »
BTW 2 collisions out of 138 is 1.5%.

Offline muomega0

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Re: JSC Depot Presentation
« Reply #18 on: 05/01/2012 04:50 PM »
BTW 2 collisions out of 138 is 1.5%.
Yes, this was how the 1.5% was obtained, TMK.

Yet, rather than examine the costs of reducing the risk, providing backup, or simply adding a depot and replacing it in the case of a prop delivery mishap, AR&D events over three were excluded from further study.

Regardless, one group uses the 1.5% and reaches an entirely different conclusion.   

In the trade it appears dollars spent on AR&D risk with backups has quite an economic benefit in addition to safety.

Offline oldAtlas_Eguy

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Re: JSC Depot Presentation
« Reply #19 on: 05/01/2012 07:00 PM »
I think the key point which was emphasized by this report was that non depot and depot architectures are of basic parity in all risks to the best of the analysis of modeled risks that has significant variance for both architectures (a high lack or real data only some close approximations), but that the key decider is that depot architecture represents significant mission cost savings. Cost savings mean that more money can be spent to reduce risks making the depot architecture eventually lower cost and lower risk. The “Low Cost Access to Space” policy goal was brought up multiple times as one of the major drivers why depots should be developed.

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