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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 feel like it’s “easier” with space math because there’s so little to interfere with the course. With a golf ball, the basic math is easy, but the slightest bit of wind throws it off way beyond the acceptable error, and you can’t model all the wind perfectly.
All of these factors and more have to be taken into account if you want your predictions to be accurate. Aside from telemetry processing, most of the computing power on the ground during a space mission is used for churning out navigation solutions.
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> 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?
"As of 1 April 2026, there have been five incidents in which a spacecraft in flight suffered crew fatalities, killing a total of 15 astronauts and 4 cosmonauts.[2][how?] Of these, two had reached the internationally recognized edge of space (100 km or 62mi above sea level) when or before the incident occurred, one had reached the U.S. definition of space at 266,000 ft, and one was planned to do so. In each of these a…
Note that all the fatalities have been launch or landing related, not in space itself. Clawing out of this gravity well is tough. Make Earth a bit larger and you’d never get off it without something like NERVA or nuclear pulse Orion.
I wonder sometimes if that’s another thing to toss in the Fermi paradox bucket. Many rocky planets might be much more massive than Earth. On one with 3X our gravity a space program might never get going.
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?
The space shuttle landed like something resembling a plane, but it is more accurate to say it landed like a concrete brick traveling faster than the speed of sound. Splashdown-style landings are the simplest and safest, parachutes are always good but adding water makes for another layer of safety (and of risk, to be fair, it could sink).
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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.
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?
For reference the shuttle generally reentered at ~17.5K mph, and today's was 24K-25K mph.
It's not clear that we could build a craft with wings that could survive that. So then you're looking at adding fuel just to slow down, plus fuel for the weight of the wings themselves, plus fuel to carry all this extra fuel to the right place, etc.
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?
Apollo 13 was a very close call. If that had ended in failure the mortality rate would have been 1 in 6.
So 1 in 30 would be a pretty clear improvement from Apollo, and we are a lot better and more thorough at modeling those risks and testing systems than we were during the Apollo program.
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>Buoyancy is an easier equation to solve than lift. That's a snappy one-liner but it doesn't address the real concerns. First of all, subsonic lift is well understood and has been for decades. The answer is much more mundane: The Artemis mission profile does not require payload doors that open, no Canadarm, no requirement to service, launch, and/or capture satellites in orbit, and so like good engineers they designed…
> subsonic lift is well understood and has been for decades I said easy. Not well understood. I can fly planes. It’s hard, and has limited room for fucking up. (It’s also hyperbole to suggest we understand lift. We don’t.) Piloting a boat is easier and more forgiving. Hence, splashdown. You don’t need direction. You don’t need lift. Parachute physics is a backbreaker, but it’s symmetrical. Same for splash.
At no point were the astronauts piloting a boat. The reasons they splash down into the ocean has nothing to do with buoyancy being easier to solve, and even less to do with the ease of piloting a boat.
>It’s also hyperbole to suggest we understand lift. We don’t.
Maybe you personally do not understand lift, but "we" do in fact understand it. Please educate yourself before continuing this discussion any further.