Dear X-Air and WeatherCat armchair rocket scientists,
The main goal of any system of transportation is reliability. Seems SpaceX has had a better record of designing, building, and very importantly, reusing their system than any other group, including governments with extremely deep pockets. There?s nothing like putting ones money on the line to bring economy to a project. I?ve not seen such dedicated and enthusiastic employees since Saturn. Similar commercial groups now have a very high bar to reach much less cross.
I give the team and their leader all the applause they are due, but they aren?t yet finished in their journey.
Okay point well taken, but they are exploring territory that hasn't been tested much by previous technology and the one exception isn't entirely reassuring. There is an important reason why the Saturn V was so reliable. Every launch was a brand new vehicle. The first reusable vehicle had failures and those failures cost the lives of astronauts. Paradoxically, for reasons I cannot fathom, the part airplane and part spacecraft feature of the Space Shuttle was blamed to some extent. I think instead a significant part of the blame for both the Challenger and Columbia disasters were due to underestimating the wear and tear associated with reusing these components.
Space-X finds itself doing something that seems prudent. The Falcon 9 uses 9 of Space-X own
Merlin rocket engines. Instead of developing a new engine, Space-X is continuing to refine an proven design. The drawback is 2-fold. As I noted in my previous post, clustering a lot of engines instead of using fewer more powerful engines like in the Saturn V is risky. The second drawback is that the Merlin wasn't designed for repeated reuse. Of course the engineers will have tried to adapt it to for longevity. However, NASA engineers tried to do exactly the same thing with the Space Shuttle. It is extremely difficult to imagine all the possible failure modes and design for them. NASA wasn't able to - will Space-X avoid worn out equipment failing in some way the didn't anticipate?
Space-X and the Space Shuttle share something else that ominous - both were under enormous pressure to keep costs down. The original design for the Space Shuttle called for a Titanium skin. That would have eliminated the heat tiles that failed - dooming Columbia. According to this Wikipedia article
the development of the Falcon 9 was only 1/12 what a traditional NASA project would have cost. Now everybody wants to save money, but at what cost? I've already pointed out some trade-offs in this heavy lift design that NASA rejected in the Saturn program. What other trade-off are present that only engineers could understand? At present, the Falcon 9 has a 96% success rate. The Space Shuttle had over a 98% success rate. If we assume that Space-X maintains their launch reliability, it stands to reason that astronauts would be at least as much at a potential risk of harm as they might have been using the Space Shuttle. Is that acceptable?
In the United States we applaud success, but turns with vicious cruelty toward failure. Nobody knows what would have happened had the Space Shuttle as originally proposed had been built instead of the desperately scaled down version. Rocket science is the ultimate example of
"playing with fire." Enthusiasm is no guarantee of infallibility and the engineers at Space-X should never forget they are building machines upon whom lives will eventually depend. That's what their boss had demanded. Is Elon Musk ready to accept the responsibility for death's of astronauts? If is isn't, then he shouldn't be the CEO of Space-X.
Such are the cold harsh realities of rocket science. . . . . .
Edouard