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Artemis II safely splashes down

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Re: Artemis II safely splashes down

#251

Post by hammock »

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?

Actual death rate for astronauts so far is 19/791, or 1 in 40.

Re: Artemis II safely splashes down

#252

Post by m4rtink »

Ifkaluva wrote: post #98

Can somebody help me understand why this does a water landing, like the old Apollo missions, instead of like the space shuttle that lands like a plane?

Lot of the world is ocean & they basically decided the landing point the moment they entered the free return trajectory, 9 days prior - easier to shift the landing point a little to a different place in the ocean place with better weather tha. to switch to a backup airport.

With lunar landing flights they would still have to choose 4 days before, as long as they do direct return.

Eventually you want to break to Earth orbit (propulsively or aerodynamically) and board a dedidacted craft for landing. But till then water landing capsules work.

Re: Artemis II safely splashes down

#253

Post by areoform »

curiousObject wrote: post #185
areoform wrote: post #104

Earlier quoted context omitted.

Thanks! note - I can't verify any of the following, it's more - for lack of a better term - aerospace nerd fan theory at this point. Post-collapse, people think that the Buran justification was paranoia. But based on what I've read / seen (though this is getting hard to source, so I might be just good ol' hallucinating here), they weren't entirely wrong. The subtext around that large payload bay had to do with the So…

> documented attempt to capture Salyut-7 https://www.thespacereview.com/article/2554/1 This isn’t true. The same article even explains that. From that article: “It takes only some basic fact checking to debunk all the preposterous allegations…”

Yes, you're right. I'm not going to pretend that this is a serious proposition. There isn't a lot of evidence to support it.

For me, it's a fun conspiracy theory to engage with. I'm only doing this for the love of the game as it were. Please don't take it that seriously.

But you have to admit, it is a fun theory. A lot of the claims made by the Russians / Roscosmos are most likely false, but if you notice the article says,

    > The only concrete document referred to is an intelligence memo that Defense Minister Sokolov supposedly received on February 24 about the assignment of the French astronauts. Whether such a memo really landed on his desk that day is questionable (after all, Baudry’s assignment to 51E had been publicly announced by NASA in August 1984), but the idea that the assignment raised some suspicions in Soviet circles about the objectives of the Challenger mission may not be so far-fetched. There had always been a high level of paranoia in the Soviet Union about the military potential of the Space Shuttle. Misconceptions about the military applications of the shuttle, such as the belief that it was capable of diving into the atmosphere to drop bombs over Moscow, had been a key factor in the Soviet decision to develop Buran in 1976. The Buran orbiter was a virtual carbon copy of its US counterpart in shape and dimensions, exactly to counter the perceived military threat of the Shuttle. Furthermore, a couple of developments in the Shuttle program in early 1985 may have fueled the Soviet paranoia. The Shuttle had flown its first dedicated Defense Department mission (STS-51C) in January 1985 and a controversial laser experiment in the framework of SDI was planned for the STS-51G mission in June.
Whether or not said documentation can be trusted, which bits could be taken as true v. what's just insane paranoia is something that would require more work to discount than most would think. Because, as I've said, the numbers do line up from the article,

    > The least one can say is that Salyut-7, which was 13.5 meters long and had a maximum diameter of 4.15 meters, would have fit inside the Shuttle’s cargo bay, whose dimensions were 4.6 by 18 meters. In fact, after the final crewed mission to Salyut-7 in 1986, the Russians significantly raised its orbit in hopes that one day it could be retrieved by Buran, which had the same dimensions as the American shuttle.
The Shuttle was an amazing piece of technology with amazing capabilities. See: https://en.wikipedia.org/wiki/STS-41-C and https://en.wikipedia.org/wiki/STS-49

and this is one of my favorite missions, https://en.wikipedia.org/wiki/STS-51-A (with my favorite space selfie)

Fun fact, the original deorbit plan for the Hubble was for the Shuttle to bring it back and then put it inside the Smithsonian, https://www.hou.usra.edu/meetings/orbitaldebris2019/orbital2...

(the Smithsonian part is IRL lore, and isn't mentioned online, AFAICT)

Re: Artemis II safely splashes down

#254

Post by GMoromisato »

dibujaron wrote: post #166
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.

While I agree with your main point (it's hard to know who was right), the people who agreed to proceed were NASA engineers/astronauts who had actual numbers to analyze, while the doubters (even Camarda) only had theories.

Re: Artemis II safely splashes down

#255

Post by m4rtink »

devilbunny wrote: post #29
hydrogen7800 wrote: post #17

Earlier quoted context omitted.

My suspicion was they were burning excess propellant, rather than attitude adjustment while under the parachutes. Though who knows how much propellant remained. It could be quite a bit more than it appears was used.

Not just excess - excess and toxic. Hydrazine derivatives and nitrogen tetroxide, IIRC. They are hypergolic, too, so the easiest way to vent them is just to run the engines until empty. However, to prevent moving the craft too much, you do short bursts.

On the press conference they mentioned the RCS was used to orient the craft with the most sturdy part facing down for the ocean impact.

Otherwise I would also just bet on RCS venting like in Apollo.

Re: Artemis II safely splashes down

#256

Post by m4rtink »

pwndByDeath wrote: post #237
tomhow wrote: post #186

Earlier quoted context omitted.

The guidelines ask us to avoid being curmudgeonly. I'm sure you didn't mean to come across that way, but could you try not to make Hacker News the kind of place that responds with “meh” to a successful space mission?

My pessimism comes from a hindsight that the Apollo missions, while amazing failed to create the future they promised. Looking at how the missions were designed, the political focus, the academic infighting of NASA scientists trying to keep niche research funded. I fail to see how this time, the same strategy will produce a different result. I also don't expect benevolent billionaires to fill that either. I hope I wo…

I blame the "space race" narrative - it made everything unsustainably expensive just to beat the goal of landing on the Moon by the end of the decade and before the Soviets. That also made the program even more dependant on political whims and easy target for budget cuts in the Vietnam era.

I recommend looking into the space flight plans from the pre Apollo - while tere were bonkers ideas like Project Horizon, most of the plans sounded quite sensible, with incremental building of space infrastructure and emphasis on cost and reusability (in the 1960s).

Of course when it became a race all the sustainability and infrastructure went out of the window and got sacrificed in the name of speed. :P

Re: Artemis II safely splashes down

#257

Post by m4rtink »

adamsb6 wrote: post #55
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…

They can't just build Apollo 18 and resume the program as if there weren't a 50 year hiatus. Imagine if your employer wanted to start using a software system it retired in 1972. What would you do?

Just another monday in any big old company adjecent to finance or airline industry ? ;-)

Re: Artemis II safely splashes down

#258

Post by post-it »

dingaling wrote: post #106
philistine wrote: post #23

Earlier quoted context omitted.

I’d bet a million dollars that Orion will win every safety metric compared to the shuttle once it is retired. NASA deluded itself in thinking the Shuttle was safe. The reality is that the Shuttle was the most dangerous spaceship anyone ever built.

Artemis rides on extended versions of the same SRBs that made the Shuttle ascent so dangerous.

It has a launch escape system, unlike the shuttle.

Re: Artemis II safely splashes down

#259

Post by rvnx »

BoredPositron wrote: post #38

I don't know how to describe the feeling but it feels like a bad movie remake. Maybe I am just a sucker for practical effects and not 2020s CGI to stick with the metaphor and conspiracy...

In 2028, so only 2 years from now. They will be able to bring 4K pictures and videos of the walk on the moon and they promised not to delete them this time.

They will have Nikon cameras, GoPros, and iPhones with them.

Very different from the videos taken with the Gameboy Camera.

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