Coming in hot!

December 12, 2023 11:51 AM

POV footage of NASA's Artemis 1's Orion spacecraft's re-entry into the Earth's atmosphere: Real-time (25m); Time-lapsed 25x (1m)
posted by not_on_display (29 comments total)

At times the sounds in the short version are uncannily like those of a human exhaling breath,
posted by Paul Slade at 12:06 PM on December 12, 2023

That window needs a squeegee!
posted by grumpybear69 at 12:09 PM on December 12, 2023

Welcom home o pure maiden, shooter of stags, goddess of the moon.
posted by Abehammerb Lincoln at 12:28 PM on December 12, 2023 [8 favorites]

Very cool! But did remind me of this.
posted by TedW at 12:43 PM on December 12, 2023

In the realtime video, when you see the flame tail around 5 minutes and again around 13 minutes, there's a series of clunking noises that correspond to changes in the shape of the flame. Some kind of attitude adjustment mechanism?
posted by echo target at 12:55 PM on December 12, 2023 [2 favorites]

Forgive a little sentiment, but my best friend growing up was named Orion. He studied physics, but unfortunately died quite young. It makes me extremely happy to think that, if he knew he shared a name with a NASA spacecraft, there is no force in this galaxy or any other that would have shut him up about it.
posted by Phobos the Space Potato at 12:56 PM on December 12, 2023 [31 favorites]

Aw Phobos <3 you brought a tear to my eye.
posted by MiraK at 1:00 PM on December 12, 2023

Very cool, the only way it could have been more epic is if someone had climbed out and started surfing.
posted by The Card Cheat at 1:09 PM on December 12, 2023 [3 favorites]

In the realtime video, when you see the flame tail around 5 minutes and again around 13 minutes, there's a series of clunking noises that correspond to changes in the shape of the flame. Some kind of attitude adjustment mechanism?

I am ... very uncomfortable with how not-silent reentry is. Also with seeing what is presumably ablated heat shielding landing on the window like ash.
posted by thecaddy at 1:20 PM on December 12, 2023

Brief explanation of what we’re seeing via thespacegal TikTok.
posted by Brandon Blatcher at 1:34 PM on December 12, 2023 [5 favorites]

I believe the clunking is the attitude jets turning on and off. The plume changes shape because of their exhaust.

Note: Not "altitude" jets. /shakes fist at the movie version of The Martian

Very cool, the only way it could have been more epic is if someone had climbed out and started surfing.

I was expecting this.
posted by The Tensor at 1:38 PM on December 12, 2023 [2 favorites]

Very cool, but next time they need to add an accelerometer.
posted by Tell Me No Lies at 1:43 PM on December 12, 2023 [2 favorites]

I loved how not-hollywood the fiery-sparky re-entry looked. Like, if a CG shop had submitted it for the next blockbuster film, it would have been rejected because it didn’t look “real.”
posted by Thorzdad at 1:49 PM on December 12, 2023 [5 favorites]

I'm gonna add a bit of commentary about this, because not only is this awesome footage, it's showing something extremely cool that had never been done before.

With Apollo and other capsules, you'd always hear about how the entry angle was critical - come in too steep and you'd burn up, come in too shallow and you'd bounce off the atmosphere back into space. Well, now they're deliberately bouncing the re-entry. And not just bouncing it - they're skipping it across the top of atmosphere like a stone across a pond.

The heatshield starts burning hard at about 4:30 into the video. Then at 5:16, the thrusters fire to roll it over. It's a circular capsule, but by design, its center of gravity isn't quite in the middle. So by rolling it, you can adjust how it balances. That means the roll control translates into pitch control. By rolling it they're adjusting the angle of attack.

Now see what happens as a result - until that point, the clouds had been getting steadily closer, but from about 6:00, the surface is receding again. They pitched it up and bounced off the atmosphere, hard enough that the capsule goes almost all the way back into space - from a low point of about 60km altitude up to just shy of the Karman line.

Slowly gravity brings it back, and from around 14:00 it re-enters a second time. And now it's rolling almost constantly to adjust the trajectory. You know how when you skip a stone just right, it doesn't plop into the water at the end, but instead the bounces get closer and closer together until it's just sliding across the top of the water? It's doing something like that, but with precision control.

Between tweaking the initial bounce, and the adjustments in the final descent, they can pick exactly where to put the capsule down over something like a 5000 mile range. They get to spread out the deceleration over a longer period, so the astronauts don't have to sit through 6.4g like they did on Apollo. And they get to cool off the heatshield - by the time it's made that long arc after the first re-entry, it's coming in cold again.

Artemis may look a lot like a re-run of Apollo. But the sheer level of engineering confidence on display here is incomparable. Not only did NASA pull this trick off: they decided to make it a core function which the safety of the mission would depend on. They automated it such that the spacecraft could do it by itself with nobody in the cockpit. And it worked, perfectly, the very first time.

It is an absolute flex of control engineering, every bit as impressive as SpaceX landing rockets on the pad.
posted by automatronic at 3:31 PM on December 12, 2023 [102 favorites]

Put them together -- replace/add a parachute stage that's a steerable airfoil so after all that the capsule parks itself right on the LAND HERE spot.

DO IT DO IT DO IT DO IT. palpatine_do_it.gif
posted by GCU Sweet and Full of Grace at 4:37 PM on December 12, 2023

> not only is this awesome footage, it's showing something extremely cool that had never been done before.

Thanks for that explanation automatronic—it brings everything I'm watching into a much cooler context than simply "woah, planet! clouds! fire!!" Concisely written and packed dense with useful info. Flagged as a great comment.
posted by not_on_display at 5:15 PM on December 12, 2023

Put them together -- replace/add a parachute stage that's a steerable airfoil so after all that the capsule parks itself right on the LAND HERE spot.

That's functionally exactly what the Space Shuttle was, and the Soviets even fully automated the process - Buran only ever flew uncrewed, and landed by itself within 10 metres of target - in 1988!
posted by automatronic at 5:25 PM on December 12, 2023 [2 favorites]

Shoutout to Commander Moonikin Campos, a "purposeful passenger" who embodies the kind of quiet dignity so lacking in our leaders today.
posted by PlusDistance at 6:01 PM on December 12, 2023 [4 favorites]

The skip entry maneuver is pretty cool, well done Artemis. But I think Gemini was an even bigger flex, having literally the first on-board flight computer. Not as good as Artemis because it couldn't do fancy integrals, but it could actively steer the capsule down to anywhere in a 500 mile range with about 15 mile accuracy (well, except for Gemini 3, and only Gemini 11 did a fully automated reentry because test pilots.)
posted by credulous at 7:27 PM on December 12, 2023 [1 favorite]

Non-ballistic atmospheric entry. The Soviets did this a few times after flying turtles around the moon.
posted by credulous at 7:31 PM on December 12, 2023 [1 favorite]

That was beautiful, thank you for posting. I may watch it again, possibly more than once. So glowy, so graceful, so clonky, then splash. The parachutes feel alive like they are smiling. And this really happened, from space to water in a half hour, like it was nothing, like we do this sort of thing every day. Sometimes living in the future turns out OK.
posted by bigbigdog at 8:08 PM on December 12, 2023 [1 favorite]

If you cue it at just the right moment, the skip maneuver goes perfectly with the re-entry music from Gravity.
posted by automatronic at 8:31 PM on December 12, 2023 [2 favorites]

we're in the pipe five by five
posted by They sucked his brains out! at 9:28 PM on December 12, 2023 [8 favorites]

>They get to spread out the deceleration over a longer period, so the astronauts don't have to sit through 6.4g like they did on Apollo.

Apollo 10 apparently flew much of its reentry at 200,000'.

Apollo 11 was similar, I guess

(there is much kookery on the internet poisoning google results!)
posted by torokunai at 4:11 AM on December 13, 2023

That's functionally exactly what the Space Shuttle was

I think I was assuming that steerable parachutes wouldn't weigh *THAT* much more than normalsies...
posted by GCU Sweet and Full of Grace at 5:33 AM on December 13, 2023

Put them together -- replace/add a parachute stage that's a steerable airfoil so after all that the capsule parks itself right on the LAND HERE spot.

Gemini Rogallo. There were test flights but as we all know they ultimately went with regular parachutes.
posted by swr at 6:43 AM on December 13, 2023 [1 favorite]

Mod note: Automatronic's comment and this post have entered the upper atmosphere of the Best Of blog!
posted by Brandon Blatcher (staff) at 9:56 AM on December 13, 2023 [5 favorites]

Something that may be incredibly obvious to everyone but was only made clear to me by my Percy-Jackson-obsessed 10-year old: In Greek Mythology, Artemis is Apollo's twin sister. I know that's why they chose the name but for some reason it never clicked!
posted by montag2k at 1:06 PM on December 13, 2023 [1 favorite]

I remember watching the Gemini rendezvous maneuver one winter when I was seven or so and afterwards running my sled through a hole in the ice into the Creek (a couple feet deep and in northern Wisconsin). The rendezvous is by far the more vivid memory. So, it is with extreme embarrassment that I say I didn’t realize this was the manned capsule they’re working on to return to the moon. I’d got so used to the idea that nothing was ever fucking happening again in space (at least by NASA) that it completely escaped me.

Extremely cool. I figured when I was ten that it was reasonable to expect to spend my 42nd birthday on the moon (2000, that is) if I could save a reasonable amount of cash in time…. Maybe I was right, but it should have been my 142nd! Thanks for posting.
posted by Gilgamesh's Chauffeur at 7:39 PM on December 13, 2023