Comment by Arthurian
2 days ago
2cents from a kid who grew up in a NASA family during the shuttle years - As others have commented, NASA’s baseline objective is to not kill astronauts. My understanding of their ethos growing up was that there was absolutely no excuse not to pursue excellence and prioritize safety when people’s lives were on the line. One would have to think that goal is fundamentally incompatible with SpaceX’s way of doing things (see the many exploding rockets - who wants to get in that?). And from what I’ve read and heard through the grapevine, working with SpaceX as a contractor on Artemis has certainly had pain points related to these mismatched priorities.
SpaceX has the most reliable orbital launch vehicle ever made. Falcon 9 block 5 has had 550 successful launches out of 551 attempts, giving it a 99.8% success rate. For comparison, Soyuz-2's success rate is 97%, Ariane 5 is 95.7%, and the Space Shuttle was 98.5%. All of these are worse than Falcon 9's block 5's landing success rate of 98.9% (552 out of 558 attempts[1]).
The current Starship launches are part of a development and testing program. They expect quite a few failures (though probably not as many as they've experienced). But since each Starship launch is only 1/25th the cost of an SLS launch, SpaceX can afford to blow up a lot of them. And they won't put people on them until they have a track record of safe operation. Falcon 9 didn't have crew on it until the 85th launch.
1. The number of landing attempts is higher than the number of launches because Falcon Heavy results in multiple landings per launch.
You risk it when there are no people on board to find the issues. Fix issues, rinse repeat.
NASA/Congress pushes the armchair quarterback approach. Analyze forever, fail because analysis isn't the same thing as real world experience, get stuck using 50 year old rocket technology. Each engine on SLS cost more than the entire Starship super heavy launch vehicle.
By weight the RS-25 engines cost about 70% of that of building their 7000lb mass dry mass out of gold. That's insane.
NASA says its baseline is to not kill astronauts and yet it is currently planning to send astronauts on a mission in space with an Environmental Control System on its first space flight in a capsule that has flown in space once, and was different on that one flight, and had unexpected heat shield problems with another different heat shield and on a untested return path that is guessed to fix the issues. Actions speak louder than words.
The shuttle lost two crews. Maybe pushing its limits in unmanned testing would have prevented those incidents.
I don't think so, because both losses were due to bad management decisions under irrational political pressure, not any lack of engineering knowledge that more unmanned testing could have provided.
Challenger was lost because NASA ignored a critical flight risk with the SRB joint O-rings. And by "ignored", I mean "documented that the risk existed, that it could result in loss of vehicle and loss of lives of the crew, and then waived the risk so the Shuttle could keep flying instead of being grounded until the issue was fixed". They didn't need more unmanned testing to find the issue; they needed to stop ignoring it. But that was politically unacceptable since it would have meant grounding the Shuttle until the issue was fixed.
Columbia was lost because NASA ignored the risks of tile damage due to their belief that it couldn't be fixed anyway once the Shuttle was in orbit. But that meant NASA also devoted no effort to eliminating the risk of tile damage by fixing the issue that caused it. Which again would have been politically unacceptable since it would have meant grounding the Shuttle until the issue was fixed.
Wrong. Both were lost because of a fundamentally BAD ARCHITECTURE. And that architecture was bad because the NASA engineers who designed it, had never designed anything like it before and were never able to test or evaluate any of their assumptions.
Columbia would not have been lost if the Shuttle was top stacked, instead of side stacked.
Challenger would not have been lost if not for the use of solid rockets to launch humans.
Both of these design decisions were done to reduce development effort.
> They didn't need more unmanned testing to find the issue; they needed to stop ignoring it.
Should such testing have been needed? No.
Was such testing needed, given NASA's political pressures and management? Maybe. Unmanned testing in similar conditions before putting humans on it might've resulted in a nice explosion without loss of life that would've been much harder to ignore than "the hypothesizing of those worrywart engineers," and might've provided the necessary ammunition to resist said political pressures.
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Testing wasn't really the issue with the loss of the two shuttles. In both cases, it was mostly a management issue. For Challenger NASA had seen o-ring erosion in earlier launches, and decided it was not a big risk to the crew. Then they launched Challenger against the recommendations of the engineers in charge of o-ring seals. For Columbia, they has seen foam strikes in earlier launches, but since they had not caused catastrophe in the past, they decided that foam strikes were acceptable. Even when it was clear that a large foam strike had occurred on the launch of Columbia, management wasn't concerned enough to try to get ground-based images of the shuttle to check for damage. Could Columbia's crew have been saved had they known the extent of the damage? No one can say of course, but not even trying to do everything possible was inexcusable.
They very nearly lost the first shuttle they launched. Jumping straight into manned testing was quite reckless, but politically necessary. If they had tested the shuttle without crew, that would have gotten people thinking that crews probably aren't necessary for a lot of shuttle missions, in particular launching satellites. It also would have prompted people to compare the cost of shuttle launches to other unmanned rocket launches, in particular for commercial satellite launches (which they were doing until the Challenger disaster.) These are comparisons that would have been very problematic for NASA as a political entity.
> They very nearly lost the first shuttle they launched.
Which mission are you referring to?
If it's STS-1, AFAIK there were no close call incidents during the actual flight, but the mission commander, John Young, did have to veto a suggestion to make that mission an RTLS abort instead of an actual orbital flight. Doing that would have been reckless, yes: Young's reason for not doing it was "Let's not practice Russian roulette."
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The lesson is that people can be irrational even it the logic is sound.
The problem there is the Shuttle was deliberately designed so it couldn’t be flown unmanned, which risked lives and wasted money for lots of simple satellite launches.