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Comment by chha | Hacker News Reader

Impressive for sure, but I have to admit that the first thing I thought it would be was the launch of the Apollo 17 lunar module: https://youtu.be/9HQfauGJaTs?si=2smTf9G3tomXPpot

Filmed using the rover camera remote controlled from Houston, with a latency of about a second from a command was sent until the camera responded

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I've referred to that clip in past conversations about future moon missions revisiting relics like the Apollo 11's flag and the first footprints.

People tend to forget every manned moon landing site is also a launch site. Sure, there's no atmosphere to disturb the dust since we left, but the liftoff exhaust didn't care much about that.

A launch that knocked over the flag over eight meters away[1] almost certainly also left a smoothly blown-out depression where most of the first footprints were, no matter how inert the site has been since then.

And beside that, between the two of them there was enough traffic in and out of the module that the first footprints were probably stepped on over and over again.

[1] https://history.nasa.gov/alsj/ApolloFlags-Condition.html

The LEM separates at launch from the moon. The descent module remains behind. When the ascent engine fires, it blows the gas on top of the descent module below it. The descent module, having a mostly flat top, would direct gas sideways, blowing away the tall flag, but not the footprints.

That’s actually an interesting thought… on earth, such a redirection of the exhaust gas wouldn’t mean much, since the resulting turbulence would cause the surrounding air to get caught up in the wake of the exhaust anyway (making everything around it disturbed), but with no atmosphere? The result would look a lot different. I still think the footprints would be affected because the exhaust deflection is not perfect or complete, but it’s interesting to think about the idea of exhaust traveling thousands of miles per hour just a few feet above the lunar surface while the surface itself remains undisturbed.

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