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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
(Score: 0) by Anonymous Coward on Monday January 15 2018, @04:09PM
"NASA concluded that it would be feasible to move the crewed flight forward to EM-1"
Flying humans on a first flight seems to be ignoring Murphy.
The safety sim and analysis addresses things from one viewpoint, but as good as it is, it will never get everything.
A real, honest flight test increases the test coverage far over the analysis.
Aside from political (budget?) concerns, what is the rush?
Fortunately, NASA appears to have pushed back on this.
"The ASAP strongly recommends that NASA be resourced and begin construction of a second MLP as soon as possible"
EM-1 and EM-2 need different MLP configurations.
Instead of coordinating a way so that the same MLP can handle this (Perhaps with extra arms), they want a second MLP.
This seems poor systems planning resulting in excellent funding for the folks at KSC.
For somebody trying to accomplish something, seems like a misuse of funds.
"Additionally, if the alternative (helium) tanks are only flown for
NASA missions, the potential hazards and impacts arising from operating a unique F9 vehicle at a relatively
low flight rate (as compared to SpaceX launches for other customers) would need to be carefully assessed."
Space-X should not let NASA do this. Cheap access to space requires that things work in excess of NASA historical odds for crew safety.
If the new tank is necessary for this, then it should be used universally.
If not, then it should not because doing so makes the crewed flight 'special' which means less tested.
We don't want NASA to make Space-X become the current NASA.