Quote from: woods170 on 07/16/2018 05:39 pmQuote from: erioladastra on 07/16/2018 05:09 pmQuote from: Arb on 07/15/2018 07:24 pmQuote from: erioladastra on 07/14/2018 10:04 pmAnd 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.htmlThe 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.
Quote from: erioladastra on 07/16/2018 05:09 pmQuote from: Arb on 07/15/2018 07:24 pmQuote from: erioladastra on 07/14/2018 10:04 pmAnd 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.htmlThe stuck valve problem was not life-threatening. It was solved long before the spacecraft got in any real trouble.
Quote from: Arb on 07/15/2018 07:24 pmQuote from: erioladastra on 07/14/2018 10:04 pmAnd 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
Quote from: erioladastra on 07/14/2018 10:04 pmAnd 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?
And yes Dragon had some issues that could have been life threatening as has been accounted for in books and articles.
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.
Quote from: ncb1397 on 07/16/2018 06:02 pmQuote from: woods170 on 07/16/2018 05:39 pmQuote from: erioladastra on 07/16/2018 05:09 pmQuote from: Arb on 07/15/2018 07:24 pmQuote from: erioladastra on 07/14/2018 10:04 pmAnd 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.htmlThe 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.
Later in that same thread they note that Elon said they can deorbit with just one thruster quad working.
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.
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.
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.
Quote from: speedevil on 07/13/2018 05:25 pmhttps://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?
Whether a particular environment model is reflective of reality is a separate discussion that doesn't have any bearing on meeting requirements.
Ultimately, it depends on how each vehicle's requirements are written.
Quote from: SWGlassPit on 07/19/2018 06:51 pmUltimately, it depends on how each vehicle's requirements are written.There was some discussion on this in the recent GAO report.
Quote from: gongora on 07/19/2018 07:26 pmQuote from: SWGlassPit on 07/19/2018 06:51 pmUltimately, 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?
Quote from: Comga on 07/19/2018 09:46 pmAnd 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.
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?
Quote from: gongora on 07/20/2018 12:32 amQuote from: Comga on 07/19/2018 09:46 pmAnd 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.
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 testAfter 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."