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Certifying a vehicle based on a test/qualification flight that was such a failure that it was considered too risky to let the crew fly back on the vehicle sound
by tgsovlerkhgsel 2y ago
Certifying a vehicle based on a test/qualification flight that was such a failure that it was considered too risky to let the crew fly back on the vehicle sounds about as reasonable as letting Boeing self-certify their airplane safety (instead of FAA oversight), or adding an automated nosedive-the-plane system with a non-redundant sensor just to avoid some training.
Sure, it is cheap, but when, not if, it results in deaths, it will be really hard to justify why someone thought it was a reasonable choice.
- cowsandmilk 2y agoAn unmanned flight back still significantly narrows the ban of what the risks are and if the return is successful, the returned craft will certainly be inspected in extreme detail.
- JonChesterfield 2y agoThe returned craft is going to be hard to reassemble from the pieces scattered across the surface of the planet, whether there were people in it or not.
- jjk166 2y agoSo long as the crew capsule makes it back properly, that means the service module was good enough to get the job done. They'd also have data collected during the return voyage.
- HPsquared 2y agoIt's unlikely to actually fail, just not unlikely enough to send the astronauts in.
- Aaargh20318 2y agoThe problem is in the service module which will be jettisoned and burn up in the atmosphere.
- deleted 2y ago[deleted]
- ragebol 2y agoThere is also a risk with Dragon, just estimated to be lower. But both are still space capsules, there is a risk involved with both.
- pfdietz 2y agoThey're safer than the Shuttle was, though. Capsules are designed (I believe) to survive total loss of control on entry, although a purely ballistic entry can have decelerations of up to 15 gees, IIRC.
- pixl97 2y agoThe capsule will survive, the strawberry jelly on the inside, not so much.
- pfdietz 2y agoThere's at least one Soviet entry that happened ballistically, IIRC, with no deaths (they had other deaths on entry, but for other reasons like loss of air or tangling of parachute lines.) The peak acceleration on ballistic entry is independent of the ballistic coefficient of the entry vehicle (but is a function of the L/D ratio during lifting entry; even small L/D can greatly reduce the peak acceleration.)
- jjk166 2y agoThis is a semantic failure. There's risk to everything. But there is a qualitative difference between the risk something might malfunction and that something which has already malfunctioned might be dangerous. A house full of fire hazards which is nevertheless not on fire can not be directly compared to a house that is currently on fire.
- GMoromisato 2y agoYou should read about Apollo 6: https://en.wikipedia.org/wiki/Apollo_6 https://en.wikipedia.org/wiki/Apollo_6 Apollo 6 was an uncrewed test flight of the Saturn V. It was almost a disaster. Pogo oscillations almost tore the vehicle apart. And after staging, two engines shut down early and the rocket had to go into a lower orbit than planned. But that flight was enough to certify the Saturn V for human use and they launched 3 astronauts to the moon on the next Saturn V flight, Apollo 8.
- HeyLaughingBoy 2y agoOne of the interesting things about testing is how you interpret the results. e.g., you have to run three test cases with passing results to pass the overall test and certify the system. So, you run the test. All three test cases pass with flying colors, but during test #3, something that you hadn't thought of came up and it could be a problem. What do you do now? You've reached your stated qualification for passing the test but now there's this wrinkle. Which one should take precedence in certifying the system for use?
- peterfirefly 2y agoAnd pogo oscillations continued to be a big problem for the Saturn V rockets...