Author Topic: Commercial Crew Schedule Analysis  (Read 397591 times)

Offline Comga

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Re: Commercial Crew Schedule Analysis
« Reply #600 on: 07/17/2018 05:44 am »
There is a lot of concern trolling on this thread.
The LA Times article was anything but condemning of SpaceX.
The "tin snips" story?  A triumph. Then they solved the root problem. 
The stuck valves?  Solved with the first approach.  If it hadn't they would have tried something else.  Never happened again.
Water intrusion?  Small impact at the time. (Loss of cooling)  Worked through that issue.
The COPV?  Big mess.  A new effect.  Solved it themselves but now may use NASA solution on NASA's dime.
MMOD?  There is not really enough data.  A long chain of uncertain values beyond the limits of adequate statistics.  NASA will have to decide when it's "good enough".  It may never be.  That's a big part of the schedule issue.
We went to the moon through extreme risk because it was an important national goal, more than safety, as are many things people have to do.
Perhaps NASA will decide that preserving the $100B ISS is an important goal and worth some additional risk.
That schedule is running out of margin, as OMB noted.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline woods170

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Re: Commercial Crew Schedule Analysis
« Reply #601 on: 07/17/2018 08:00 am »
And yes Dragon had some issues that could have been life threatening as has been accounted for in books and articles.
Must have missed those; which books and articles?

For example,

http://www.latimes.com/business/la-fi-spacex-trouble-book-20180316-story.html


The stuck valve problem was not life-threatening. It was solved long before the spacecraft got in any real trouble.


How is losing control of your vehicle in an environment like space for 4 or 5 hours not life threatening? There was a real chance their fix wouldn't work.


What is little reported is that one of four RCS quads was fully operational, from the moment Dragon separated from Falcon 9 v1.0, with a second one being partially operative (one RCS thruster failed on the second quad).
Together they had enough control of the spacecraft to maintain attitude.


However, mission rules required all four quads to be fully operational before Dragon could attempt to approach the ISS.


But, Dragon was capable of doing the de-orbit burn with those two quads alone. In fact, that would have been the plan had the attempts, to activate the other two quads, been unsuccessful.


The rush to fix the problem was not due to attitude problems (Dragon was holding attitude just fine), but due to the need to do an orbit-raising burn.
Without that burn Dragon would have had no chance to reach the ISS. De-orbit would have been necessary.
But the entire episode never was potentially life threatening, had a crew been on-board:
- The vehicle was holding attitude
- The vehicle was capable of controlled de-orbit
- Solar arrays were deployed and sun-tracking
- Vehicle ECS was working fine.
- Vehicle comms were working fine.

Offline jpo234

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Re: Commercial Crew Schedule Analysis
« Reply #602 on: 07/17/2018 04:25 pm »


Mike Pence will visit Cape Canaveral next month for a big space update

Quote
Pence, who chairs the National Space Council, will confirm a new launch date for the first private crew missions and announce which crew capsules each of the four selected astronauts will ride in to the International Space Station.
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline mn

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Re: Commercial Crew Schedule Analysis
« Reply #603 on: 07/17/2018 05:28 pm »
And yes Dragon had some issues that could have been life threatening as has been accounted for in books and articles.
Must have missed those; which books and articles?

For example,

http://www.latimes.com/business/la-fi-spacex-trouble-book-20180316-story.html


The stuck valve problem was not life-threatening. It was solved long before the spacecraft got in any real trouble.


How is losing control of your vehicle in an environment like space for 4 or 5 hours not life threatening? There was a real chance their fix wouldn't work.


What is little reported is that one of four RCS quads was fully operational, from the moment Dragon separated from Falcon 9 v1.0, with a second one being partially operative (one RCS thruster failed on the second quad).
Together they had enough control of the spacecraft to maintain attitude.


However, mission rules required all four quads to be fully operational before Dragon could attempt to approach the ISS.


But, Dragon was capable of doing the de-orbit burn with those two quads alone. In fact, that would have been the plan had the attempts, to activate the other two quads, been unsuccessful.


The rush to fix the problem was not due to attitude problems (Dragon was holding attitude just fine), but due to the need to do an orbit-raising burn.
Without that burn Dragon would have had no chance to reach the ISS. De-orbit would have been necessary.
But the entire episode never was potentially life threatening, had a crew been on-board:
- The vehicle was holding attitude
- The vehicle was capable of controlled de-orbit
- Solar arrays were deployed and sun-tracking
- Vehicle ECS was working fine.
- Vehicle comms were working fine.

What is the source that they could have deorbited?

According to the CRS-2 thread, extending the solar arrays slowed the rotation of the spacecraft. (https://forum.nasaspaceflight.com/index.php?topic=31239.msg1020087#msg1020087)

Doesn't that imply that they did not have full attitude control at the time.

The question was asked if they could have deorbited without fixing the issue, I don't recall seeing a response.

Offline whitelancer64

Re: Commercial Crew Schedule Analysis
« Reply #604 on: 07/17/2018 05:35 pm »
Later in that same thread they note that Elon said they can deorbit with just one thruster quad working.
"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 mn

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Re: Commercial Crew Schedule Analysis
« Reply #605 on: 07/17/2018 05:52 pm »
Later in that same thread they note that Elon said they can deorbit with just one thruster quad working.

A: Thank's missed that on my first quick re-read of 32 pages ;) (and here's a link for those who can't find it https://forum.nasaspaceflight.com/index.php?topic=31239.msg1020110#msg1020110)

B: I'd say that was hardly a given, it sounds more like in the worst case they would try something and maybe it'l work...

Offline Comga

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Re: Commercial Crew Schedule Analysis
« Reply #606 on: 07/18/2018 05:20 am »

Mike Pence will visit Cape Canaveral next month for a big space update

Quote
Pence, who chairs the National Space Council, will confirm a new launch date for the first private crew missions and announce which crew capsules each of the four selected astronauts will ride in to the International Space Station.

Pence?
"big space update" next month?
Is this "Celebrity Apprentice Astronaut"?
Spiro Agnew didn't announce that Armstrong would command Apollo 11.....
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline erioladastra

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Re: Commercial Crew Schedule Analysis
« Reply #607 on: 07/18/2018 05:11 pm »
There is a lot of concern trolling on this thread.
The LA Times article was anything but condemning of SpaceX.
The "tin snips" story?  A triumph. Then they solved the root problem. 
The stuck valves?  Solved with the first approach.  If it hadn't they would have tried something else.  Never happened again.
Water intrusion?  Small impact at the time. (Loss of cooling)  Worked through that issue.
The COPV?  Big mess.  A new effect.  Solved it themselves but now may use NASA solution on NASA's dime.
MMOD?  There is not really enough data.  A long chain of uncertain values beyond the limits of adequate statistics.  NASA will have to decide when it's "good enough".  It may never be.  That's a big part of the schedule issue.
We went to the moon through extreme risk because it was an important national goal, more than safety, as are many things people have to do.
Perhaps NASA will decide that preserving the $100B ISS is an important goal and worth some additional risk.
That schedule is running out of margin, as OMB noted.

I wasn't trolling.  I stated that Dragon had issues "that could have been life threatening " which is a true statement (and the article also doesn't have all the details either).  I was pointing out to the poster that while SpaceX has done an amazing job on is unmanned cargo vehicle it has not been without incident.  No sure how that amounts to trolling.

Offline Chris Bergin

Re: Commercial Crew Schedule Analysis
« Reply #608 on: 07/18/2018 07:04 pm »
Everyone calm down (and no we're not discussing the diver thing here, so one post removed).
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Offline billh

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Re: Commercial Crew Schedule Analysis
« Reply #609 on: 07/19/2018 05:49 pm »
https://directory.eoportal.org/web/eoportal/satellite-missions/s/space-fence - I strongly recommend if interested in MMOD. Space Fence is an ongoing project to upgrade the capability of tracking MMOD.



There are _lots_ more unobserved particles of course that this will not be able to track, but it's at least a start.

When I saw this graph I was struck by this thought: I wonder if the Chinese had not shot down Fengyun-1C, would the Dragon and Starliner spacecraft be meeting NASA's LOC/LOM requirements now?

Offline yg1968

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Re: Commercial Crew Schedule Analysis
« Reply #610 on: 07/19/2018 06:26 pm »
https://directory.eoportal.org/web/eoportal/satellite-missions/s/space-fence - I strongly recommend if interested in MMOD. Space Fence is an ongoing project to upgrade the capability of tracking MMOD.



There are _lots_ more unobserved particles of course that this will not be able to track, but it's at least a start.

When I saw this graph I was struck by this thought: I wonder if the Chinese had not shot down Fengyun-1C, would the Dragon and Starliner spacecraft be meeting NASA's LOC/LOM requirements now?

Not long after it happenned, Mike Griffin was asked a very similar question during a Congressionnal hearing. His answer was that debris from this event has or will dissipate over time and that the increase in MMOD risks wasn't significant.
« Last Edit: 07/19/2018 06:31 pm by yg1968 »

Offline SWGlassPit

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Re: Commercial Crew Schedule Analysis
« Reply #611 on: 07/19/2018 06:51 pm »
https://directory.eoportal.org/web/eoportal/satellite-missions/s/space-fence - I strongly recommend if interested in MMOD. Space Fence is an ongoing project to upgrade the capability of tracking MMOD.



There are _lots_ more unobserved particles of course that this will not be able to track, but it's at least a start.

When I saw this graph I was struck by this thought: I wonder if the Chinese had not shot down Fengyun-1C, would the Dragon and Starliner spacecraft be meeting NASA's LOC/LOM requirements now?

The answer to this is trickier than you might think.  It depends on which orbital debris environment model Dragon and Starliner are using for LOC/LOM requirements.  The ORDEM2000 model was the established model at the time requirements were being crafted and wouldn't include debris from that event, while the ORDEM 3.0 model was crafted later and would.  Which environment would be written into a particular vehicle's requirements would depend on the result of negotiations between NASA and that particular provider.

Ultimately, it depends on how each vehicle's requirements are written.  Whether a particular environment model is reflective of reality is a separate discussion that doesn't have any bearing on meeting requirements.

Offline Kansan52

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Re: Commercial Crew Schedule Analysis
« Reply #612 on: 07/19/2018 06:53 pm »
Whether a particular environment model is reflective of reality is a separate discussion that doesn't have any bearing on meeting requirements.

How true.

Online gongora

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Re: Commercial Crew Schedule Analysis
« Reply #613 on: 07/19/2018 07:26 pm »
Ultimately, it depends on how each vehicle's requirements are written.

There was some discussion on this in the recent GAO report.

Offline Comga

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Re: Commercial Crew Schedule Analysis
« Reply #614 on: 07/19/2018 09:46 pm »
Ultimately, it depends on how each vehicle's requirements are written.

There was some discussion on this in the recent GAO report.

And what did they say other than "Danger Will Robinson!"?
Or is that off topic for this discussion of schedule? 
If so, do you have a link to an appropriate discussion thread?
« Last Edit: 07/19/2018 09:47 pm by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online gongora

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Re: Commercial Crew Schedule Analysis
« Reply #615 on: 07/20/2018 12:32 am »
Ultimately, it depends on how each vehicle's requirements are written.

There was some discussion on this in the recent GAO report.

And what did they say other than "Danger Will Robinson!"?
Or is that off topic for this discussion of schedule? 
If so, do you have a link to an appropriate discussion thread?

You could actually look at the document  ::)  Start reading on page 22, which is page 26 of the pdf file.

Offline Comga

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Re: Commercial Crew Schedule Analysis
« Reply #616 on: 07/20/2018 03:57 pm »
And what did they say other than "Danger Will Robinson!"?
Or is that off topic for this discussion of schedule? 
If so, do you have a link to an appropriate discussion thread?

You could actually look at the document  ::)  Start reading on page 22, which is page 26 of the pdf file.

Thanks for the document. I did read it. It will take more than a virtual keyboard on a phone to compose a real comment.

However, just one first:
OMB found 4 elements of the review process have five ways (one applying different criteria to Boeing and SpaceX) for Loss of Crew probabilities to disparate and mostly arbitrary targets, and says that if the contractors don’t meet the goal, they can apply for a “waiver” with even less definition. It will be at that point that the program decides if human spaceflight is still worth significant risk.

It is odd that OMB, an organization formed to perform numerical analysis  (“Budget”) didn’t examine the single number at the center of the issue: 270. NASA wants the LoC <1/270. From where does that strange number come. (It was 1000 back at the start of Constellation IIRC.)  It appears that it’s twice the number of Shuttle flights. (2x135) setting the goal at exactly 4 times better than the track record of the Shuttle.

Has this been elucidated to the knowledge of anyone here?

An interesting aspect of the MMOD issue is that China has bolstered their position as one of only two countries that can launch humans by filling LEO with debris to a level that may be intolerable to others.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online DigitalMan

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Re: Commercial Crew Schedule Analysis
« Reply #617 on: 07/20/2018 05:03 pm »
It seems to me both commercial crew vehicles have a more complicated path to achieving LOC numbers compared to shuttle since they have to stay attached to ISS for 6 months, no?  Shuttle had a smaller window of opportunity for damage in space.

And what did they say other than "Danger Will Robinson!"?
Or is that off topic for this discussion of schedule? 
If so, do you have a link to an appropriate discussion thread?

You could actually look at the document  ::)  Start reading on page 22, which is page 26 of the pdf file.

Thanks for the document. I did read it. It will take more than a virtual keyboard on a phone to compose a real comment.

However, just one first:
OMB found 4 elements of the review process have five ways (one applying different criteria to Boeing and SpaceX) for Loss of Crew probabilities to disparate and mostly arbitrary targets, and says that if the contractors don’t meet the goal, they can apply for a “waiver” with even less definition. It will be at that point that the program decides if human spaceflight is still worth significant risk.

It is odd that OMB, an organization formed to perform numerical analysis  (“Budget”) didn’t examine the single number at the center of the issue: 270. NASA wants the LoC <1/270. From where does that strange number come. (It was 1000 back at the start of Constellation IIRC.)  It appears that it’s twice the number of Shuttle flights. (2x135) setting the goal at exactly 4 times better than the track record of the Shuttle.

Has this been elucidated to the knowledge of anyone here?

An interesting aspect of the MMOD issue is that China has bolstered their position as one of only two countries that can launch humans by filling LEO with debris to a level that may be intolerable to others.

Offline Rebel44

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Re: Commercial Crew Schedule Analysis
« Reply #618 on: 07/21/2018 07:08 pm »
https://arstechnica.com/science/2018/07/boeing-may-have-suffered-a-setback-with-starliners-pad-abort-test/

Boeing suffers a setback with Starliner’s pad abort test
After the initial report, the company confirmed the issue.

"We have been conducting a thorough investigation with assistance from our NASA and industry partners," the statement said. "We are confident we found the cause and are moving forward with corrective action. Flight safety and risk mitigation are why we conduct such rigorous testing, and anomalies are a natural part of any test program."

"One source indicated that this problem may not affect the uncrewed test flight but that it could delay the crew test."

Online oldAtlas_Eguy

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Re: Commercial Crew Schedule Analysis
« Reply #619 on: 07/22/2018 08:32 pm »
https://arstechnica.com/science/2018/07/boeing-may-have-suffered-a-setback-with-starliners-pad-abort-test/

Boeing suffers a setback with Starliner’s pad abort test
After the initial report, the company confirmed the issue.

"We have been conducting a thorough investigation with assistance from our NASA and industry partners," the statement said. "We are confident we found the cause and are moving forward with corrective action. Flight safety and risk mitigation are why we conduct such rigorous testing, and anomalies are a natural part of any test program."

"One source indicated that this problem may not affect the uncrewed test flight but that it could delay the crew test."
Depends on how much of a schedule pad there is between the abort test and the crewed flight. If they had significant schedule padding between the events then the crewed test flight schedule would only be minor affected by this setback. If management is bad at doing their job then this setback will ripple through such that each week of slip for the Abort test will result in a slip of a week for the NET date for the crew flight.

 

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