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Artemis II safely splashes down

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Re: Artemis II safely splashes down

#351
post #342

Earlier quoted context omitted.

In that case aliens from a super Earth would be unable to get off it unless they decided to salt their biosphere with fissile waste. NERVA is at least contained if it works properly. So no space program from a super Earth until they figure out not just fusion but compact high density fusion that could fly. You’d need stuff like in The Expanse, or at least in that rough ballpark. Using fission is something they probab…

I think a launch loop would still work, even on a Super Earth: https://en.wikipedia.org/wiki/Launch_loop Or potentially beamed power for launch, so you don't kug a power source. But in any case, indeed much harder. :)

Yeah.

I’m a little obsessed with Orion though. The fact that the math works on that lunacy. The good old devil’s pogo stick.

If you could make pure fusion bombs it would be maybe politically viable, especially if you also use superconducting magnets to make it less just brute force. You’d still induce a little radioactivity from neutrons but it would be short lived and not even close to fissile fallout bad.

To see that thing launch. From somewhere very remote though, probably Antarctica. And from many miles away, and probably with welders glass. But damn. That would be epic.

Re: Artemis II safely splashes down

#353

Earlier quoted context omitted.

I wondered about that. Winching someone who can barely walk and is wearing a spacesuit into a helicopter over choppy water is safer and quicker than parking them on a motor boat and sailing back to the mothership? What was the real reason? Tradition? Lack of imagination? Photo opportunities? The rest was great tho.

Is 10 days enough to make walking difficult?

People get wobbly legs after spending a few days on a cruise ship at sea.

I would assume spending 10 days in zero G is orders of magnitude more chaotic for your motor skills.

Re: Artemis II safely splashes down

#354

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…

Huh? The research done to develop the flight control computer for Apollo (and IBCMs of the time) lead directly to modern microcomputers. It’s hard to name something more impactful than that.

It could easily have taken another decade or two to develop the modern computer if not for the resources spent in the space program at that time. It still would have happened, but Apollo and the space program was soaking up something like 90% of computer demand for a full decade. Computers went from room sized behemoths to the size of a file cabinet in that time.

Re: Artemis II safely splashes down

#355
Fake news?? I've heard a radio item today where they informed that the internet has a lot of conspiracy theories that Artemis isn't real, images are AI fakes and reports are completely made up. They then proceeded to post a "prove" image which was definitely AI since one of the people only had one arm. lol. Anyway, glad it worked out. I do think that somehow we have more important issues to solve than discovering the moon, but whatever.

Re: Artemis II safely splashes down

#356

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…

>The Shuttle was risky, but it wasn't thought of or acknowledged by NASA as being risky until very late in its lifecycle.

The whole idea of the shuttle program was to make space travel routine and less-risky. Like air travel.

It obviously failed at that goal.

Re: Artemis II safely splashes down

#357
post #174

Earlier quoted context omitted.

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…

Thanks for sharing your article - very well written. I am stunned to see that LoC risk assessment. I kept wondering to myself over the past week, “will this be the last USA-supported human space travel if these astronauts don’t survive?” I’d have a hard time imagining the general public would support any future missions if they hadn’t survived. These astronauts are some elite humans. My respect for them is even great…

This happened twice already with U.S. manned missions, and with 7 person crews.

Re: Artemis II safely splashes down

#358
post #242

Earlier quoted context omitted.

Is 12 enough of a sample size to make a statistical judgement? What if there were 20 more which didn’t have a loss of life? Is it then 1/30? What if there were 20 more? The risk factor is calculated _per mission_ from what I understand. You can have three accidents in a row and nothing for decades but the risk itself can still be 1 in 30.

So the risk factor for Apollo could have actually been 1/1000 but they were just really unlucky?

Yes, actually. This is similar to having a 100 year flood five years in a row. It doesn’t mean that the flood occurs only once in 100 years. _On average_ it’s 1/100 probability of occurring in any given year.

But then, Apollo 1 was after all the first mission on the Saturn V. I think we should assess even its pre-launch risk much higher than the rest of them. Similarly Artemis II has a much higher risk than the subsequent ones will have.

Re: Artemis II safely splashes down

#359
post #242

Earlier quoted context omitted.

Is 12 enough of a sample size to make a statistical judgement? What if there were 20 more which didn’t have a loss of life? Is it then 1/30? What if there were 20 more? The risk factor is calculated _per mission_ from what I understand. You can have three accidents in a row and nothing for decades but the risk itself can still be 1 in 30.

Your point is fair and and important distinction. I think when estimating a risk factor though, this empirical data, while a low sample size, is a valuable statistic because it's empirical, and not that small of a sample size. Maybe going forward, we have 3 risk levels: - Historical. Low N as you say. (Even though each mission and spacecraft is different and they're spread out over time, there's value in this) - Bure…

Yes. It provides a prior for Bayesian analysis if nothing else.

Re: Artemis II safely splashes down

#360

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. So with 4 crew members, chance of one dying was 13%! Very lucky they all survived.

That is not how statistical calculations of risk are made. If the crew has 1/30 crew mortality rate, and there were 30 crew members, that does not mean there is a 100% chance that one dies. While there is negligible chances that only a portion of the crew were to return, the outcomes are closer to black and white of nearly 29/30 full crew return and 1/30 no crew return.
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