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Artemis II safely splashes down

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Re: Artemis II safely splashes down

#321

Post by fluidcruft »

small_model wrote: post #281

Impressive mission but I feel it's not capturing the public attention because it's actually a step back from the mission 50 years ago when they actually landed men on the moon with tech that was orders or magnitude simpler and less powerful.

I've noticed there's a pretty big difference between the people who remember how routine shuttle flights became and the younger crowd at work. I do think Artimis is cool, but I will admit to being a bit jaded about it as a GenX who watched Challenger live in 2nd grade. The GenZ at work seem genuinely delighted. And that's pretty cool.

Re: Artemis II safely splashes down

#322

Post by bombcar »

m4rtink wrote: post #235
bombcar wrote: post #121

Earlier quoted context omitted.

The analogies for these things like "hitting a golf ball into a hole in one 5,000 miles away" are always fun. I like starting from the fact that Ptolemy was able to get the accuracy of the "motions of the heavens" down so well that it took more than a thousand years to get observations that showed discrepancies. The math, it maths.

I always feel like these analogies don't really fit the real space flight as you quite often have a lot of time to correct the trajectory if you get it roughly right during launch and even that takes a couple minutes. You also have closed circuit guidance and external radar stations to verify the trajectory. You really don't have anything like that when playing golf, so I don't thin it is a good analogy. But for the…

There’s a big difference (not really as much as you might think because fuel is limited) between a single shot with no thrusters and a rocket that has all sorts of adjustments possible.

It’s all in fun, really, like the old analogies involving hard drive heads and jet planes.

Re: Artemis II safely splashes down

#323

Post by groundzeros2015 »

dingaling wrote: post #111
qrush wrote: post #22

Apparently there's more work than just clicking "Recover Vessel" after splashdown!

1 hour 29 minutes seems excessive to extract the astronauts; if any of them _did_ have a medical issue they'd be in for a long wait. The commentary said that the initial problems with the boats approaching Integrity was due to an unexpected swell. Unexpected, in the Pacific? Edit: all of the Apollo missions, except 8, had their stabilization collars inflated in under 20 minutes. With Integrity today it took nearly an…

Uh yes. Doing space missions is dangerous and unexpected things can happen.

Re: Artemis II safely splashes down

#325

Post by Someone »

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. Roughly 3x riskier than the shuttle

Do you have a link? I’m asking because it is very easy to make mistakes when comparing risks. For example https://news.ycombinator.com/item?id=47725961 translates that into “That if we send 30 people we _accept_ that one is possible to die.” If that interpretation is correct, given Artemis has a crew of four, that looks more like a 1:120 chance of a mortality of 4. I think that would make it an improvement over the space shuttle.

Re: Artemis II safely splashes down

#326

Post by class3shock »

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…

If I may be allowed one nitpick. Without fully understanding the FAA doc you link to in the article, I think it would be better to say something like loss of a plane is a 1 in a billion event for commercial airplanes. Many types of parts used in airplanes and jet engines break at much higher rates though, they just don't necessarily cause a plane loss when they do.

Re: Artemis II safely splashes down

#327

Post by ericcumbee »

Applejinx wrote: post #314
slow_typist wrote: post #302

Earlier quoted context omitted.

Wouldn’t the soviets or any other adversary prepare against letting NASA capture their satellites? You need a very small amount of C4 in the satellite to destroy the shuttle in the event of capture. Tampering with other entity‘s satellites can best be done with satellites. That also frees resources needed for bringing life support systems to orbit.

But at that point if you're building in a self-destruct for a weapon that can be so dangerous it's worth sending a shuttle to take it away from you, surely it's better to adversarially trigger the self-destruct and not bother sending the shuttle. So the C4 option might simply be a bad idea: make it more difficult and costly to remove your weapon, rather than triggering your own self-destruct.

There are easier cheaper ways of destroying a satellite than sending a space shuttle. We would have only sent a space shuttle to capture it for intelligence purposes.

Re: Artemis II safely splashes down

#328

Post by ETH_start »

SloppyDrive wrote: post #228
areoform wrote: post #76

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…

Im not really convinced SLS and Artemis are best effort projects; we improve through refinement, and the only way to get there is cadence. More launches with the same general mission requirements. One launch a year is not even close to what we can manage with our current technology, to the point where the scope is too small to be legitimately worth doing. Its not solely a matter of energy; its about opportunity for l…

The value of a mission like this isn't only in the narrow technical data it returns. Its value is also institutional. Once you have an actual crewed mission orbiting the Moon, the program becomes concrete rather than aspirational. That creates momentum inside NASA and among contractors, strengthens the credibility of follow-on lunar missions, and accelerates work on the many parallel systems a sustained lunar program actually requires.

I agree entirely that it's much easier to imagine a successful moon program built around repeatable missions at high cadence, so I'm not disagreeing on that point. I would just push back on the idea that this has little or no value.

Re: Artemis II safely splashes down

#329

Post by m4rtink »

rustyhancock wrote: post #286
atonse wrote: post #101

I had to explain to my wife and kids (not that I'm in this field, but I also have to remind myself) that we are able to pinpoint where the craft will land, when it will land down to the minute, because of ... just ... math. And we're able to get them there and back because of science. It all boils down to equations that describe the world accurately, and a way of experimentation, iteration, thinking that gets us all…

I'd add a caveat to this. We can do this because of war. We know where it will land accurately because that maths and physics has been sharpened with butt loads of data. Even the reentry blackout has links to war in Plasma Stealth[0]. That data was mostly obtained because we want to know where our ICBM warheads will land. And where the enemies ICBM warheads will land so we can work on the problem of shooting them dow…

IIRC reentry plasma is actually highly radar reflective - so it is not hard to track, just hard to hit due to the speed, as there is limited time to do it.

Re: Artemis II safely splashes down

#330

Post by philwelch »

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?

If we got to a point where going to the Moon was significantly safer than that, we’d better start trying things even more ambitious and risky or we’ll stagnate as a species. The fatality rates for circumnavigating the globe or settling in North America or attempting to invent a working flying machine were much, much higher than that.
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