Comment by philistine
14 hours ago
I’d bet a million dollars that Orion will win every safety metric compared to the shuttle once it is retired. NASA deluded itself in thinking the Shuttle was safe. The reality is that the Shuttle was the most dangerous spaceship anyone ever built.
That's physically not possible due to the distances and energies involved. Even with the Commercial Cargo and Crew Program (C3P), NASA has set the acceptable mortality threshold at 1 in 270 over the entire mission and 1 in 1000 on ascent / descent. If they could set it higher by gaming the math, they would. They can't.
We're a very primitive species, and the forces involved here are genuinely new. And no, Apollo wasn't much better either, at least 10 astronauts were killed in training or burned alive (8 NASA, 2 sister MIL programs), as well as (far worse, because astronauts sign up for the risk) one member of ground staff.
People love to hate the Shuttle, and it ended up being subpar / fail expectations due to the political constraints NASA was under, but the Shuttle was a genuine advance for its time – a nonsensical, economically insane advance, but still an advance. If you look at the Shuttle alternative proposals / initial proposals as well as stuff like Dynasoar and Star Raker, you'll see NASA iterating through Starship style ideas. But those were rejected due to higher up front capital investment at the time.
The Shuttle is an odd franken-turduckling, because it was designed for one mission and one mission only. And that mission never happened. That cargo bay existed to capture certain Soviet assets and deploy + task certain American space assets and then bring them back to Earth.
And that's the bit that's hard to emphasize. The fact that the Shuttle could put a satellite up there, watch it fail, then go back up, grab it, bring it back, repair it, then launch again was an insane capability.
Was the program a giant fuck up at the end? Yes. But does that mean Artemis will be safer than the Shuttle? No. That's not how the energetics, time from civilization, acceptable risk profiles etc. work out.
Shameless plug, wrote a bit about the Apollo hagiography, Artemis and risk here – https://1517.substack.com/p/1-in-30-artemis-greatness-and-ri...
It’s statistically unsound to compare results of low probability events like this.
https://en.wikipedia.org/wiki/Texas_sharpshooter_fallacy
How could a comparison between such dissimilar programs ever be meaningful? NASA flew 135 Shuttle missions over the course of 30 years; Orion will be doing well to approach a tenth of that number.
Space flight safety is a function of culture and I don’t have any confidence that the culture has improved.
I think we are a long way along from digging out Dr Feynman to look into why a shuttle exploded.
Unless you happen to have some deep links into NASA, in which case please elucidate us all, then why not celebrate a happy and safe return from a sodding dangerous mission that involved things like >25,000 mph relative velocity and some remarkable navigation.
When you depart earth (close quarters gravity, air resistance, things in the way), everything moves really fast, really fast and any acceleration becomes an issue really ... fast!
The moon moves, the earth moves: both famously in some sort of weird dance around each other and both orbit around the sun. Obviously the moon affects the earth way less than vice versa but it still complicates things.
I think that NASA did a remarkable job of making Artemis II look almost routine and I don't think that was down to behaving as they did in the past.
> I think that NASA did a remarkable job of making Artemis II look almost routine and I don't think that was down to behaving as they did in the past.
I have been excited for Artemis--yes it's big and expensive and late, but look how it has brought out the best of what humans can be--but, despite all that, the heat shield situation was textbook "normalization of deviance." Just as the O-rings were not designed to have any damage but they retroactively justified it was okay, just as there was not supposed to be any foam or tile damage but they retroactively justified it was okay, so too was the Artemis I heat shield not supposed to come back with damage, but they...
I'm not trying to be negative, and risks are inevitable, but the resemblance to me was uncanny. The lesson with normalization of deviance is that a successful result does not inherently mean a safe decision. After all, most of the time that you play Russian Roulette you will escape unharmed.
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Artemis rides on extended versions of the same SRBs that made the Shuttle ascent so dangerous.
Yes, and the four RS-25 main engines on the SLS rocket (Space Launch System) are literally SSME's harvested from the shuttles (Space Shuttle Main Engine). Of course that means they are re-usable. So sad to see them plummet to the ocean floor. Perversely Rocketdyne is building cheaper non-reusable versions of the RS-25 for future missions.
It has a launch escape system, unlike the shuttle.
Was any shuttle lost to the SRBs?
Yes, Challenger - although program management knew they were violating a launch constraint (temperature), and it was the low temperature that produced the conditions necessary for SRB failure.
As with any aerospace mishap, it's a chain of events, not just one cause.
Yes, challenger. The O-ring failed, creating a gas exhaust that almost instantly destroyed the main propellant tank.
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Yes, 50% of shuttle losses were due to SRB failures (Challenger)
That's exactly how Challenger was lost.
The Artemis SRBs incorporate design changes to address the causes of the Challenger failure. Specifically they changed the joint design, added another o-ring, and they have electric joint heaters to keep the seals warm.