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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: 4, Insightful) by frojack on Sunday January 14 2018, @08:04PM (17 children)
Too damned safe?
1 in 500 is worse odds [fool.com] and Airforce or Navy combat pilots face, and higher than all combat deaths. Almost every other job death rate is measured in deaths per 100,000 workers.
SpaceX has spent more time perfecting rocket return and landing than safe crew delivery.
Half the people here just hand waive into existence the ability to land on mars, mine the asteroids, build colonies on the moon.
A no greater than a 1-in-270 "loss of crew" is a ridiculously low bar for a profession some people around here insist must become commonplace.
No, you are mistaken. I've always had this sig.
(Score: 4, Insightful) by takyon on Sunday January 14 2018, @08:12PM (2 children)
Can these odds even be effectively measured? Most space accidents seem to be caused by one-time design problems which are discovered and fixed in the aftermath. The low launch rate (of an individual rocket+spacecraft, or the industry overall) contributes to the uncertainty. Previous accidents hurt the record (SpaceX's two worst explosions get brought up constantly) but make future craft safer.
What could be safer? Single-stage-to-orbit spaceplanes? Abandonment of chemical rockets altogether in some EmDrive/stolen UFO scenario?
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(Score: 2, Interesting) by tftp on Sunday January 14 2018, @09:22PM (1 child)
Something like that. Chemical rockets are a dead end anyway because they are too inefficient and too expensive. They are dangerous because we have to work with huge energies that are contained in materials that are unsafe even on their own. Spaceflight on chemical rockets cannot become a path to somewhere for the people. It can be only a narrow, dangerous road for researchers who don't mind sitting atop a flying bomb.
Would be nice to have an elevator to orbit, but chances are that we won't be capable of producing and installing it until we don't need it.
If we do not invent the technologies to, say, fly within the gravity field of the planet, we have little chance of conquering other planets. Other worlds are large planets, and there will be only few teams on them. They will need a flying vehicle that can fly half the planet on single tank of fuel, hover and land anywhere (VTOL) and be very reliable. No service for tens of flights! Of course, it should not depend on atmosphere - even in our system we have quite a variety of those. People say that the martian colony starts with a base, and then sends crawlers with scientists up to several thousand miles away. Aside from lack of such efficient machines, those crews are playing with death. There are no comm or gps sats around Mars and no plans to deploy them. There is no (?) ionosphere that supports SW hops. UHF goes straight through. How will they call for help? How soon they will be saved? This is why flying vehicles are essential for study of a planet. They also cover huge distances that no crawler can.
As it stands, all current plans of manned presence in space resemble ill equipped individuals, alone attacking Everest. This rarely works. Sensible space exploration requires many technologies (robots, engines, controlled fusion) that we do not have yet. It only makes sense to go back to the drawing board and invent what we need rather than to pave the planets with dead bodies of pioneers. There is no emergency, Moon and Mars aren't going anywhere in nearest 100 years. There is no benefit trying to set up there right now.
(Score: 1, Troll) by Ethanol-fueled on Sunday January 14 2018, @10:54PM
The problem was that these are California hipsters we're dealing with and they think that carbon fiber is the solution to all of their problems just because their yuppie bicycles and twice-used stand-up paddleboards have the carbon fiber wrap.
(Score: 1) by khallow on Sunday January 14 2018, @09:05PM (13 children)
(Score: 0) by Anonymous Coward on Sunday January 14 2018, @10:54PM (6 children)
So the 50/50 odds for a coin toss don't make any sense unless we are going to sit there and flip the damn coin one hundred times? Methinks someone is lacking a basic understanding of probability.
(Score: 4, Touché) by takyon on Sunday January 14 2018, @11:31PM
1. We don't know the real odds before it launches.
2. It won't launch often enough for us to determine the real odds. Space Launch System has 12 planned launches [wikipedia.org] over a 14 year period. Only 7 of them will be crewed, and three of the launches will be on the second main variant of the design, Block 2. There's probably not enough coin flips for disaster to strike.
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(Score: 3, Informative) by khallow on Monday January 15 2018, @12:47AM (4 children)
As to manned space flight, it hasn't happened often enough to bother with a 1 in 500 LOC rate. We've only had 320 crewed launches since the beginning of space exploration. There is no basis for asserting such a high reliability. We could, for example, have several 1 in 500 LOC risks that apply to every manned launch ever made, that just haven't happened yet. In the face of that level of ignorance, it makes no sense to demand high standards of reliability.
(Score: 4, Interesting) by JoeMerchant on Monday January 15 2018, @04:58AM (3 children)
You're right that we're ignorant of the "true" (better stated as "statistically reliable") rates of failure in use: insufficient data.
You're wrong that attempting to design for high standards of reliability is senseless. It's quite expensive to train new astronauts and build replacement vehicles, not to mention politically difficult to fund a program that makes us look foolish and incompetent.
When there's insufficient test-trial data to base failure rate analysis on, the engineers pull numbers out of any convenient orifice and throw them into a risk management table - in med devices there's a whole standardized ISO procedure for doing just that. The "guess" numbers are tossed around between the best experts available until they reach consensus - the process is documented as a design review, and we move on to the next problem. I imagine in NASA's manned programs they include such available data as they have to inform their guesses. You'd be surprised at just how valuable these risk management processes turn out to be, even when the best experts available can't point to massive records of previous experience.
Even the Space Shuttle managed to successfully take off and land in 132 of 134 tries. You don't get to that level of reliability without designing for it.
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(Score: 1) by khallow on Monday January 15 2018, @07:53AM (2 children)
It can be worse than senseless. For example, such design can actually introduce risks that are higher than the ones that the effort is trying to reduce. It can also create moral hazards and other systemic or behavior problems that increase risk.
And having a few dozen manned launches already under one's belt.
(Score: 0) by Anonymous Coward on Monday January 15 2018, @08:40AM (1 child)
Say what?
And you didn't even mentioned ethical hazards.
(Score: 1) by khallow on Monday January 15 2018, @07:02PM
(Score: 2) by frojack on Monday January 15 2018, @01:25AM (5 children)
20 times?
There were 135 space shuttle missions. About 146 Soyuz missions counting all Soyuz models.
With SpaceX bringing the price of a launch down you can expect the capsules being developed now to have a long service life, including flying multiple missions in the same vehicle.
Just after the Challenger disaster the entire US space program had a 4% fatality rating, which quickly dropped until the Columbia ramped it up again. Its been declining ever since.
The only reason NASA want's to restrict commercial providers to no better than 1 in 270, is that is just about their overall record.
No, you are mistaken. I've always had this sig.
(Score: 2, Interesting) by khallow on Monday January 15 2018, @02:38AM (4 children)
(Score: 0) by Anonymous Coward on Monday January 15 2018, @05:12AM (3 children)
Apollo 1 doesn't count, I guess?
(Score: 1) by khallow on Monday January 15 2018, @06:45AM (2 children)
Correct, it wasn't a launch.
(Score: 2) by choose another one on Monday January 15 2018, @09:22AM
Umm, nor was the SpaceX COPV explosion being talked about in TFA - it was during fueling for static fire test.
If we don't count pre-launch failures on the pad then SpaceX's record suddenly looks awful lot better.
If we do, NASA's record looks worse.
That is one of the problems when you have very little data - tweaking definitions ever so slightly to exclude or include one event can make a massive difference to your "safety record".
(Score: 2) by dry on Monday January 15 2018, @08:10PM
It showed a lot of design problems that would have in all probability led to flight failures. In some ways it was lucky that it failed when it did as it forced the engineers to consider things like is it smart to use a 100% oxygen environment combined with lots of flammable materials as well as simple design decisions such as how the door opens.