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posted by Fnord666 on Sunday January 14 2018, @06:53PM   Printer-friendly
from the space-is-risky dept.

Safety panel raises concerns about Falcon 9 pressure vessel for commercial crew missions

An independent safety panel recommended NASA not certify SpaceX's commercial crew system until the agency better understands the behavior of pressure vessels linked to a Falcon 9 failure in 2016. That recommendation was one of the stronger items in the annual report of the Aerospace Safety Advisory Panel (ASAP) released by NASA Jan. 11, which found that NASA was generally managing risk well on its various programs.

The report devoted a section to the composite overwrapped pressure vessels (COPVs) used to store helium in the second stage propellant tanks of the Falcon 9. The investigation into the September 2016 pad explosion that destroyed a Falcon 9 while being prepared for a static-fire test concluded that liquid oxygen in the tank got trapped between the COPV overwrap and liner and then ignited through friction or other mechanisms.

SpaceX has since changed its loading processes to avoid exposing the COPVs to similar conditions, but also agreed with NASA to redesign the COPV to reduce the risk for crewed launches. NASA has since started a "rigorous test program" to understand how the redesigned COPV behaves when exposed to liquid oxygen, the report stated. ASAP argued that completing those tests is essential before NASA can allow its astronauts to launch on the Falcon 9. "In our opinion, adequate understanding of the COPV behavior in cryogenic oxygen is an absolutely essential precursor to potential certification for human space flight," the report stated, a sentence italicized for emphasis in the report.

[...] The report raised issues in general about the commercial crew program, including concerns that neither Boeing nor SpaceX, the two companies developing vehicles to transport NASA astronauts to and from the International Space Station, will meet a requirement of no greater than a 1-in-270 "loss of crew" (LOC) risk of an accident that causes death or serious injury to a crewmember. That includes, the report stated, a risk of no more than 1 in 500 for launch and reentry.

Both programs are likely to be delayed:

Boeing, SpaceX have razor-thin margins to fly crew missions in 2018

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  • (Score: 2) by takyon on Monday January 15 2018, @01:25AM (2 children)

    by takyon (881) <> on Monday January 15 2018, @01:25AM (#622355) Journal

    I may have given SLS a bit too much credit. Maiden launch date is no earlier than December 15, 2019. So very likely to be delayed into 2020.

    I would still be surprised if BFR flew before SLS Block 1. I think BFR will face its own delays, just as Falcon Heavy did. But if it did manage to do so, that would be a great time to cancel the SLS program.

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  • (Score: 2) by choose another one on Monday January 15 2018, @10:01AM (1 child)

    by choose another one (515) Subscriber Badge on Monday January 15 2018, @10:01AM (#622508)

    I think BFR will face its own delays, just as Falcon Heavy did.

    I am sure it will, but in the end it just might be a better bet than falcon heavy. I think KSP and the magic struts have given a lot of people a very misleading impression of how easy it is to "just" strap a few well tested rockets together and have them stay together (the hard bit) through launch. FH might work, but may face insurmountable problems - and this stuff is too complex to simulate fully, it'll have to launch. This is why Elon is downplaying expectations for FH.

    BFR on the other hand is in many ways a simpler design and may have fewer problems as a result. The new fuel / engine work seems to be on track and much of the rest is "just" scaling up the vehicle. BFRs biggest problem is probably the size and hence the cost, very deep pockets may be needed which might be a problem particularly if Tesla starts to struggle. I would not discount Blue Origin purely for that reason, although they are a long way behind at the moment.

    • (Score: 2) by takyon on Monday January 15 2018, @12:04PM

      by takyon (881) <> on Monday January 15 2018, @12:04PM (#622536) Journal

      BFR launches are supposed to be cheaper than Falcon 9 launches. That can only be achievable because part of it is designed to be reusable, as opposed to F9 and FH that throw away the second stage.

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