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Artemis II safely splashes down

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Re: Artemis II safely splashes down

#361

Post by throwanem »

randallsquared wrote: post #317
throwanem wrote: post #114

Earlier quoted context omitted.

The only people who took seriously the idea of a Shuttle FOBS were the Soviets, and frankly not even all of them; as far as I've ever seen credible evidence to substantiate, it never went much past a single position paper from the early 80s. The idea that Buran was meant as a MAD-restoring FOBS has, so far as I know, not even that much support. (If you know of primary sources, in translation or otherwise, please link…

> If Reagan had violated the Outer Space Treaty - via NASA of all agencies! - how do you imagine it'd have stayed secret over these forty years just past? While I have no reason to believe this particular escapade, I do expect that there are a thousand such wild stories that have remained secret. Watergate seems obvious and explosive to moderns, but at the time it could easily have gone undiscovered or unremarked. Ho…

Thousands? Millions? Trillions? Hectoseptisquintillions? "Ignorance is not a datum." Teach that as catechism from 1975 and we might have been spared the "rationalist" scourge altogether.

Re: Artemis II safely splashes down

#362

Post by pwndByDeath »

pitched wrote: post #350
brcmthrowaway wrote: post #54

Earlier quoted context omitted.

What is delta v/critical mass?

Fictional books about asteroid mining, from what my Google searches are returning. I would love to learn that it was a real thing though

Suarez is, IMO, very good at researching current/near tech and mixing it into a good story about what is possible with what we have right now. Nothing in the books is really out of our reach except the will and perhaps strategic discipline to make and execute the plan.

Re: Artemis II safely splashes down

#363

Post by anon291 »

BitsAndObjects wrote: post #313
anon291 wrote: post #183

Earlier quoted context omitted.

All those countries are essentially American vassals. No shade to them, just stating the reality, and not really sure why we need to keep pretending. There's no shame in that. It's often the smartest move to join forces with the big guy in the block!

You need to travel more.

I've been to many of them and, unlike most Americans, when I say I've traveled the world, that also includes countries that are not in the American sphere of influence. The difference in how that plays out is obvious. I would recommend you travel more. Ideally to a country where if anything happens, uncle sams pressure won't do anything.

In countries like China, Russia, or even India, you won't find as many American products. The influence of Hollywood is much less. American styles of doing things are not necessarily the ones chosen for civic institutions. American agencies don't work as closely with their scientific enterprises as the American allies. On the other hand, they have strong armies that are not beholden to what America dictates, as evidenced by how often they end up in conflict.

As an example, the world sanctioned Russia and... nothing happened... because Russia is a real country able to build its own things. It has industrial capacity, mining capacity, and the organization to do that independently of what others think. It also has an army willing to defend it.

The countries you listed do not have these things. Their 'army' to defend the nation is a vague promise that they'll think about while they ask America to carry out their interests. American magnanimity usually means this is a safe bet.

Then we can talk

Re: Artemis II safely splashes down

#364

Post by masklinn »

masklinn wrote: post #265
magicalhippo wrote: post #165

Earlier quoted context omitted.

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…

In my understanding of the Manley video, the materials change will only occur for Artemis 3, for which it will be irrelevant as that will not be leaving LEO.

Not sure why I'm being downvoted. Here's the segment where Manley explains this: https://youtu.be/shcj7MUK5BU?t=828 and this is also the section where Manley explains Artemis III is not going to the moon so it won't actually be testing this change.

And from an older NASA explanation: https://www.nasa.gov/news-release/nasa-shares-orion-heat-shi...

> Engineers already are assembling and integrating the Orion spacecraft for Artemis III based on lessons learned from Artemis I and implementing enhancements to how heat shields for crewed returns from lunar landing missions are manufactured to achieve uniformity and consistent permeability.

Re: Artemis II safely splashes down

#365

Post by stetrain »

shash wrote: post #358
stetrain wrote: post #248

Earlier quoted context omitted.

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 subse…

But we’re talking about the risk of a defined set of events that have concluded, not a prediction of the future.

Of course Apollo would have likely had a better average if it had continued, but the risk of the Apollo program, as executed, included things like the first flight of the Saturn V.

If the final empirical mortality result of the Artemis program is 1/30 or less, it will be better than Apollo in that statistic.

A comparison of acceptable mortality is where this discussion began. If Apollo was acceptable at 1/12 (We did it, it was apparently acceptable as the program was not cancelled due to mortality rate) then an acceptable mortality of 1/30 is stronger than Apollo, not weaker.

Re: Artemis II safely splashes down

#366

Post by stetrain »

d1sxeyes wrote: post #303
stetrain wrote: post #248

Earlier quoted context omitted.

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

If I toss a coin four times and it comes up heads three and tails once, it doesn’t mean that there’s a 75% chance that this coin lands heads up. Be careful about conflating risk factor and mortality rate.

> If I toss a coin four times and it comes up heads three and tails once, it doesn’t mean that there’s a 75% chance that this coin lands heads up.

No, but it means that to ensure that I do better on my next set of coin tosses I need to beat 3 in 4, not 1 in 2.

Re: Artemis II safely splashes down

#367

Post by d1sxeyes »

stetrain wrote: post #366
d1sxeyes wrote: post #303

Earlier quoted context omitted.

If I toss a coin four times and it comes up heads three and tails once, it doesn’t mean that there’s a 75% chance that this coin lands heads up. Be careful about conflating risk factor and mortality rate.

> If I toss a coin four times and it comes up heads three and tails once, it doesn’t mean that there’s a 75% chance that this coin lands heads up. No, but it means that to ensure that I do better on my next set of coin tosses I need to beat 3 in 4, not 1 in 2.

But you doing better is independent of the risk involved. The chances of you getting 3/4 heads or better is around 31%, so theres ~69% chance you’ll do worse next time round. Doesn’t change the fact that each coin toss is still 50/50.

Re: Artemis II safely splashes down

#368

Post by pwndByDeath »

mlsu wrote: post #354
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…

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 somet…

Im not sure that's an honest rhetoric, we have seen many other things in the last few years that have increased the demand for compute. It would seem lunacy to propose, to accelerate the miniaturization of compute we need to send a bunch of people to bounce around the moon, then we can forget about the space nonsense. If the goal was begin the path that leads humans into so many resources it would take centuries before fighting over something was more profit than going to the next empty rock, we clearly failed.

Re: Artemis II safely splashes down

#369

Post by BitsAndObjects »

anon291 wrote: post #363
BitsAndObjects wrote: post #313

Earlier quoted context omitted.

You need to travel more.

I've been to many of them and, unlike most Americans, when I say I've traveled the world, that also includes countries that are not in the American sphere of influence. The difference in how that plays out is obvious. I would recommend you travel more. Ideally to a country where if anything happens, uncle sams pressure won't do anything. In countries like China, Russia, or even India, you won't find as many American…

Yep, you responded exactly as expected. Well done. Enjoy your bubble.

Re: Artemis II safely splashes down

#370

Post by slibhb »

irjustin wrote: post #51
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…

> 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?

It's unclear if the shuttle was actually safer or if NASA is just more honest about the odds of catastrophic failure.

There are reasons to think Artemis is safer. It has a launch abort system that the shuttle lacked. Reentry should also be much safer under Artemis; the capsule is a much simpler object to protect.

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