Comment by vannevar
5 days ago
All of the controversy over the heat shield is obscuring the much bigger safety issue: Artemis has had only a single unmanned test flight. By contrast, the Saturn launch system had seven successful unmanned tests before being trusted with a crew, including two unmanned flights of the complete Saturn V stack. And even then, three astronauts were lost during ground testing of the crew capsule due to a critical design flaw. Artemis's closest modern counterpart, the SpaceX Starship, has had 11 test flights, several of which resulted in loss of the vehicle. There is no reason to believe that Artemis has a significantly higher reliability rate than Starship or Saturn V. Even without the heat shield controversy, this is the most dangerous mission NASA has launched since the first flight of the Space Shuttle.
> Artemis's closest modern counterpart, the SpaceX Starship, has had 11 test flights, several of which resulted in loss of the vehicle.
I don't think you can compare the two. Starship's risks are so high failure is almost the expected outcome, it's a trial and error based process. Starship and Artemis is an apples/oranges comparison with respect to how the programs approach risk tolerance.
Until Artemis actually flies a comparable number of missions, any advantage in reliability is pure speculation. Which is not a good way to approach crewed spaceflight. I don't think the two programs are as different as you think, prospectively: both take great care to ensure that their vehicles don't fail. Starships may be cheaper than the SLS, but they're still very expensive. SpaceX doesn't go into a flight expecting to lose a vehicle. The difference in culture is more in the reaction to failure. As a private company, SpaceX moves very quickly in the wake of failure, whereas NASA has in recent decades become much more cautious once a failure has occurred. And while you say SpaceX is more tolerant of risk, I would note that they've never flown a crew on a launch vehicle that had only one previous unmanned launch. Falcon 9 had 85 unmanned launches before there was a crew aboard. And they expect to launch 100 unmanned Starships before they fly one with a crew.
Now which program seems the more risk tolerant?
SpaceX was clear about their policy of flight testing earlier in the development phase. They expected to lose rockets, I do not believe those should count against the launcher.
They do not expect to lose a given vehicle. They are tolerant of losing some vehicles over time, because they understand that every flight may be affected by unknown unknowns. There is certainly no evidence that they expect to lose crewed vehicles, or that they are tolerant of crew loss.
I think the high loss rate for Starship can largely be traced back to the choice of using steel for the vehicle, which drastically reduces margins across the system. You could certainly say that they had a higher expectation of failure because they made that choice. In that sense, I understand your point. But to the best of their ability, they try to fly every vehicle successfully.
They haven't lost a crewed vehicle.
The only Starship loss that bothers me is the first one. I have no problem with "let's see if this works", I have a problem with dismissing the opinions of all the experts and launching without a flame trench. You don't need to be a rocket engineer to see that when you give all that energy no place to go a lot of it is going to get reflected back at the rocket.
What should be counted against them are the two operational Falcon 9s that were lost. The second one especially bothers me: we didn't really need that part anyway is not an answer to why the part failed!
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