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Artemis II safely splashes down

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Re: Artemis II safely splashes down

#62

Glad that they're safe and sound. It's worth pointing out that this is the first extremely public, widely acknowledged high risk mission NASA has done in over 50 years. The Shuttle was risky, but it wasn't thought of or acknowledged by NASA as being risky until very late in its lifecycle. According to NASA's OIG, Artemis acceptable crew mortality rate is 1 in 30. Roughly 3x riskier than the shuttle. There genuinely i…

> Artemis acceptable crew mortality rate is 1 in 30. This seems insane to me. That X decades later we accept, with all our advancements in tech, a weaker system than ever before. That if we send 30 people we _accept_ that one is possible to die. That's the starting point? That's what we document as acceptable?

This was the farthest humans ever travelled from earth, even farther than apollo 13. Intuitively the farther you go the higher the risks are

Re: Artemis II safely splashes down

#65

Glad that they're safe and sound. It's worth pointing out that this is the first extremely public, widely acknowledged high risk mission NASA has done in over 50 years. The Shuttle was risky, but it wasn't thought of or acknowledged by NASA as being risky until very late in its lifecycle. According to NASA's OIG, Artemis acceptable crew mortality rate is 1 in 30. Roughly 3x riskier than the shuttle. There genuinely i…

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...

Re: Artemis II safely splashes down

#67

Wild that they manage to fly to the moon but still seem to be having those comms problems. Asking the astronauts if they’re really pressing the PTT button is wild.

My friends and I have been deriving much amusement from the comms issues. We can fly people around the moon, talk with them, send back high res video, but talk to the boat that’s close enough to swim to? Forget about it!

Note: next time, pack a walkie talkie. ;-)

Re: Artemis II safely splashes down

#68
Dealing with the typical Excel foot guns during the last few hours before re-entry felt like an unnecessary risk.

Missaved their version 2 Excel spreadsheet using the wrong file name causing confusion about this version was the latest.

Nearly missed a cell in their burn sheet had multiple lines of text until mission control reminded them to resize the cell.

Re: Artemis II safely splashes down

#70

Earlier quoted context omitted.

My suspicion was they were burning excess propellant, rather than attitude adjustment while under the parachutes. Though who knows how much propellant remained. It could be quite a bit more than it appears was used.

Not just excess - excess and toxic. Hydrazine derivatives and nitrogen tetroxide, IIRC. They are hypergolic, too, so the easiest way to vent them is just to run the engines until empty. However, to prevent moving the craft too much, you do short bursts.

There should be an opposite thruster for each axis. I wonder if the short bursts were due to heating limits.
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