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Artemis II safely splashes down

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Re: Artemis II safely splashes down

#161

Post by SV_BubbleTime »

gct wrote: post #53
pictureofabear wrote: post #46

Earlier quoted context omitted.

An error in any of the orbital math may have seen them flung out into space with no chance of recovery.

Orbits do not work that way

Hilarious the the intellectual forum downvoted you for being absolutely right.

Artemis II never escaped Earth’s pull.

That video that NASA put out where the craft did a sling shop around the moon is extremely deceptive. The pull of the moon had very little effect.

If they had missed, they would have eventually crashed back to earth in the worst case, and best case just re-adjusted and returned a little bummed.

Re: Artemis II safely splashes down

#162

Post by ksymph »

areoform wrote: post #76
irjustin wrote: post #51

Earlier quoted context omitted.

> 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?

Yes, and the memories of Apollo are made rosy by hagiography. I even wrote an entire thing to explain why, https://1517.substack.com/p/1-in-30-artemis-greatness-and-ri... (yeah, shameless plug, sorry - it's more for the citations than not. You can read the standards and reports I've linked to) But if I'm allowed to repeat myself from elsewhere in the thread and the meat of the above thing, It's physically not possibl…

Nice article, although I'm not so sure about this part:

> There’s a reason why there wasn’t an Apollo 18, or 19 and 20. Even though funding had been secured, an executive decision was made to kill the program early, because LoC was inevitable.

Was funding really secure? I believe that was the main sticking point; a quick search [0] seems to confirm this, and the John Young quote below backs it up: "Even if they’d had the money..." Not to say the risk wasn't a factor too of course, but it doesn't look like funding was otherwise guaranteed.

Anyway, I think what sets the risk of the Shuttle apart from Apollo is summed up nicely in one of the quotes (in reference to the Apollo program): "The awareness of risk led to intense focus on reducing risk." In the Apollo program, there was a pattern of rigorously hunting down and eliminating any possible known risks, leaving unknowns as the primary source of risk; on the other hand, the Shuttle program let known risks accumulate continuously until crews paid the price for a bad draw.

When debris hit Atlantis on STS-27 [1] and the shuttle only survived on a one in a million stroke of luck -- the completely broken tile happened to be over an aluminum mounting plate -- it should have been taken as a free lesson on one more known source of risk to eliminate. Instead, it led to seven people dying completely preventable and unnecessary deaths a few years later.

Spaceflight is inherently risky, it's true. That's why things like the Orion heat shield are so worrisome; because it is physically possible at our current level of technology to make it safer, and yet for political / funding / etc. reasons we're not doing the best we can.

[0] https://airandspace.si.edu/stories/editorial/why-did-we-stop...

[1] https://en.wikipedia.org/wiki/STS-27

Re: Artemis II safely splashes down

#163

Post by roughly »

areoform wrote: post #11

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…

Astronauts are, as a group, extremely risk loving. Every single person who signs up to go into space knows what they’re signing up for - they’ve spent their entire life working for the opportunity to be put in a tin can and shot into orbit atop a million pounds of explosives. There’s a very valid critique that NASA has become far too risk averse - we owe it to the astronauts to give them the best possible chance to complete the mission and make it back safely, but every single person who signs up for a space mission wants to take that risk, and we don’t do anyone any favors by pretending that space can be safe, that accidents are avoidable, or that the astronauts themselves don’t know what they’re signing up for. A mission that fails should not be considered a failure unless it fails because we didn’t try hard enough.

Re: Artemis II safely splashes down

#164

Post by icehawk »

pwndByDeath wrote: post #49

As a long time space nerd, I'm not sure what this accomplishes by repeating the previous stunts that failed to usher in the promised space frontier. Apollo was, IMO, not successful at changing the course of human history. A really cool footnote, sure, but everything else that was to follow, nope, just a bunch of neat, interesting but ultimately meh science missions. An exciting change would be more like Delta-V/Criti…

We can't build a TV from 50 years ago, much less a space rocket.

Because we stopped, we get to do everything over again with hardware from this century.

Re: Artemis II safely splashes down

#165

Post by magicalhippo »

rootusrootus wrote: post #92
eqmvii wrote: post #2

Held my breath the whole time after all the heat shield warnings. Very glad it all worked, or that there was enough margin!

I was wondering about that, so I looked up the heat shield issues. It seems like their solution was very defensible and there was every reason to believe it would work out just fine. The plan that did not work as they wanted had a new idea, a double re-entry, and when the results were concerning they backed off to using a traditional single re-entry. That seems like a legitimate fix?

Scott Manley went into the details in a recent video.

The reason the heat shield failed was due to gas buildup inside the ablative material. This was due to the skip reentry profile they used, where the craft does a single skip (as in skipping stones) during reentry. The high bounce caused the shield to be heated enough that the heat penetrated the material causing gas release but not enough that the material ablated. Thus gas would build up deep inside up until it caused large chunks to break off. They could reproduce this in tests.

The fix was two-fold. First they lowered the bounce height, so a much less pronounced skip, avoiding the lowered heating of the shield. And they tweaked the material formula a bit so it was more porous, allowing subsurface gas to escape rather than build up.

Re: Artemis II safely splashes down

#166

Post by dibujaron »

1970-01-01 wrote: post #112

So the new heat shield works just fine, and NASA still knows things better than arm-chair aerospace engineers? Safety third.

It's hard to know who was right. All of these things can be true: it made it back ok; it had a high chance of making it back ok; it should've had a much higher chance of making it back ok. Most of the concerned people were stressing this last point, that it should've been safer than it was. They still thought it had a quite high chance of making it back ok. It took a lot of shuttle missions before Columbia failed.

Re: Artemis II safely splashes down

#167

Post by pdonis »

areoform wrote: post #76
irjustin wrote: post #51

Earlier quoted context omitted.

> 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?

Yes, and the memories of Apollo are made rosy by hagiography. I even wrote an entire thing to explain why, https://1517.substack.com/p/1-in-30-artemis-greatness-and-ri... (yeah, shameless plug, sorry - it's more for the citations than not. You can read the standards and reports I've linked to) But if I'm allowed to repeat myself from elsewhere in the thread and the meat of the above thing, It's physically not possibl…

The Smithsonian article on John Young that you linked to is a good one. The only John Young quote they didn't include that I wish they had was his response to the proposal to make STS-1 an on purpose RTLS abort: "Let's not practice Russian roulette."

Re: Artemis II safely splashes down

#168

Post by Brybry »

stackghost wrote: post #126
BitsAndObjects wrote: post #110

Earlier quoted context omitted.

So why do they need to use helicopters and a risky airlift to return the astronauts to the main vessel? Why not just use the speedboats to take them back? Seems really odd and I can’t find any reasonable explanation.

>Why not just use the speedboats to take them back? They actually covered this in the broadcast: Helicopters are faster to get the astronauts to medical, smoother in rough seas, and there's less risk of being swamped by a rogue wave. Plus, since the astronauts might have fatigue/muscle atrophy/whatever, it complicates potential boat transfers.

The public information sheet implies that in poor weather/rough seas they would do crew recovery in the well deck, sort of like how Dragon works. [1]

From the broadcast, they made it sound like a big factor is the 2 hour program requirement to get the crew out of the capsule. Maybe they can't reliably hit that mark with a well deck recovery?

[1] https://www3.nasa.gov/sites/default/files/files/orion-recove...

Re: Artemis II safely splashes down

#169

Post by mtlmtlmtlmtl »

areoform wrote: post #76
irjustin wrote: post #51

Earlier quoted context omitted.

> 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?

Yes, and the memories of Apollo are made rosy by hagiography. I even wrote an entire thing to explain why, https://1517.substack.com/p/1-in-30-artemis-greatness-and-ri... (yeah, shameless plug, sorry - it's more for the citations than not. You can read the standards and reports I've linked to) But if I'm allowed to repeat myself from elsewhere in the thread and the meat of the above thing, It's physically not possibl…

I often think about the shuttle program in relation to all these crazy complicated, wildly expensive, and incredibly fragile space telescopes we're sending to LEO or the Earth-Sun L2. Would be damn useful to be able to repair/upgrade these things like with Hubble.

Obviously I realise the shuttle program was pretty far away from being able to head out to the Earth-Sun L2(AB, and wasn't even working towards it. But man, it would be nice to have that ability.

Re: Artemis II safely splashes down

#170

Post by SoftTalker »

hkpack wrote: post #147
simplyluke wrote: post #118

Earlier quoted context omitted.

If you want to dispel a bit more of the ever-pervasive online pessimism bias, read up on global rates of hunger the last time we flew to the moon (1972) vs now. The reality is, for all the problems we face today, there's no sane answer other than today to the question "when would you prefer to be born as a random person on earth"

It is about trends and perceptions - 70s were very hopeful, now with global problems - wars, climate, AI, uncertainty, what is growing is desperation. I definitely don’t envy kids that are born nowadays.

The '70s were not hopeful. Economy was terrible, Vietnam ended but still hung over the culture, Watergate, Three Mile Island, Iranian hostage crisis, cold war threatening to turn hot at any moment, double-digit mortgage rates.... and Disco.
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