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Artemis II Launch Day Updates

nasa.gov

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Re: Artemis II Launch Day Updates

#161

Post by wat10000 »

russdill wrote: post #136
adamsb6 wrote: post #31

It is a bit chilling to watch these astronaut profiles having just read yesterday about the heat shield issues observed on the prior mission, and that this will be the first time we can test the heat shield in the actual pressures and temperatures that it will have to endure. Godspeed crew of Artemis II.

I mean, that's how these heat shields work. They aren't reusable, you can't test them and then use them again. Or do you mean the design? We already did Artemis I.

We already did Artemis I and the heat shield lost a lot more material than it was supposed to on that flight. "Specifically, portions of the char layer wore away differently than NASA engineers predicted, cracking and breaking off the spacecraft in fragments that created a trail of debris rather than melting away as designed. The unexpected behavior of the Avcoat creates a risk that the heat shield may not sufficiently protect the capsule’s systems and crew from the extreme heat of reentry on future missions."

Fixes have been made to the design, but they haven't been tested in flight.

Re: Artemis II Launch Day Updates

#162

Post by russdill »

4khilles wrote: post #138
russdill wrote: post #136

Earlier quoted context omitted.

I mean, that's how these heat shields work. They aren't reusable, you can't test them and then use them again. Or do you mean the design? We already did Artemis I.

The heat shield is a bit different, and the reentry profile is a bit different as well.

I suppose "this will be the first time we can test this slightly modified heat shield in the slightly different pressures and temperatures that it will have to endure." isn't quite as eye catching.

Re: Artemis II Launch Day Updates

#163

Post by adamsb6 »

russdill wrote: post #136
adamsb6 wrote: post #31

It is a bit chilling to watch these astronaut profiles having just read yesterday about the heat shield issues observed on the prior mission, and that this will be the first time we can test the heat shield in the actual pressures and temperatures that it will have to endure. Godspeed crew of Artemis II.

I mean, that's how these heat shields work. They aren't reusable, you can't test them and then use them again. Or do you mean the design? We already did Artemis I.

I mean the design.

They've changed the AVCOAT to be less permeable and altered the re-entry profile.

One of the findings of Artemis I is that lack of permeability led to trapped gas pockets which expanded and blew out pieces of heat shield. The reason for the change to be less permeable is to make it easier to perform ultrasonic testing, not to improve performance.

They altered the re-entry profile on the theory that the skip period contributed to spalling, but Charles Camarda disagrees in this doc: https://docs.google.com/document/d/1ddi792xdfNXcBwF8qpDUxmZz...

> Another chart which the Artemis Tiger Team did not intend to show on Jan. 8th, was the figure showing the spallation events as a function of time during the skip entry heating profiles (Figure 6.0-4 of NESC Report TI-23-0189 Vol. 1). In this figure, it was quite clear that the Program narrative they were feeding to the press, that it was the dwell time during the skip which allowed the gases generated to build up and cause the delta pressures which caused most of the spallation was, again, patently false. In fact, during the first heat pulse (t ≈ 0 to 240 sec), approximately 40-45% of all the medium to large chunks of ablator spalled off the Artemis I heatshield.

> Hence, varying the trajectory would do little to prevent spallation during Artemis II. I was never shown the new, modified trajectory at the Jan. 8th meeting.

Re: Artemis II Launch Day Updates

#166

Post by pc86 »

Teever wrote: post #142
zorobo wrote: post #107

Earlier quoted context omitted.

> The odds are worse if you spin each time. How do they get worse if you spin? It’s still 1/6 odds of dying,iid events.

Dude, it's a nerd-snipe conversation derailing attempt. Don't take the bait. Talk about space stuff here, not the statistical nature of Russian roulette.

How about don't tell other people what they can and can't talk about, and just ignore side threads you don't care about?

There are about 500 different HN browser extensions that let you collapse threads, btw.

Re: Artemis II Launch Day Updates

#167

Post by palata »

techteach00 wrote: post #151
xnx wrote: post #83

Earlier quoted context omitted.

Truly. I'm not sure why anyone needs to be on the rocket at all, let alone our best and brightest.

Because they want to be on the rocket. To see the moon up close with your own eyes? It's spiritual.

I understand why they want to fly. I don't understand why the people is fine paying taxes for that.

Re: Artemis II Launch Day Updates

#168

Post by adrian_b »

sarchertech wrote: post #144
runarberg wrote: post #123

Earlier quoted context omitted.

And neither are we anywhere near the capability to lunch construction workers to the moon which can build or assemble an equivalent moon base with their human labor. So this answer does not satisfy me one bit. > inspire a new generation of astronauts, engineers, and scientists This is a good point. And I would like it to be true. However when you have to lie about (or exaggerate) the scientific value of the mission,…

> And neither are we anywhere near the capability to lunch construction workers to the moon which can build or assemble an equivalent moon base with their human labor. So this answer does not satisfy me one bit. We have the capability to do that. We don’t have the will to do it, but we have the technology. We don’t even have autonomous robots that are capable of building a moon base on earth. > Your 4 year old could…

Indeed, in 1969, as a small child, I watched the Moon landing together with my parents, in Europe, like also the following missions, in the next years.

They have certainly contributed to my formation as a future engineer.

Re: Artemis II Launch Day Updates

#169

Post by gwbas1c »

CoastalCoder wrote: post #6
LorenDB wrote: post #5

It's been 54 years since humans last visited the Moon. Hopefully, in a few years we will get boots back on the surface.

Out of curiosity, why do you see this as a worthwhile endeavor? My personal perspective is that the resources are better used for other purposes, but it's possible that I just haven't encountered some compelling reason yet.

Because humans are destined to colonize space, and this is just an early step in a journey that will take hundreds or thousands of years.

More importantly, challenges like space exploration help drive knowledge and our economy; and are critical for national prestigue.

(And, most people don't focus on this, space exploration is a way for the US to demonstrate its military technology in a non-antagonistic way. There's a lot of overlap in space exploration technology and miliary technology.)

Re: Artemis II Launch Day Updates

#170

Post by pc86 »

_trampeltier wrote: post #165

Even I'm a big space fan, at moment I just can enjoy anything that comes from USA. I just can't applause to a super bully.

What a sad, disappointing instinct. It completely divorced from reality to assume that "enjoy[ing] anything that comes from [the] USA" implies any sort of political allegiance to whoever happens to sit in the Oval office at that particular point in time.

There's no way you're "a big space fan" if the first thing you think of when you see a rocket launch that was announced 9 years is Donald Trump.

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