Link: https://old.reddit.com/r/space/comments/1vcqa1p/a_spent_falcon_9_upper_stage_will_slam_into_the/

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The original was posted on /r/space by /u/StillThese3747 on 2026-08-01 15:27:07+00:00.

This is the Falcon 9 upper stage from the January 2025 launch that sent Firefly's Blue Ghost and ispace's Hakuto-R toward the Moon. Once it pushed those landers onto a translunar trajectory, it was spent. Not enough energy to escape the Earth-Moon system, not enough to fall back for a clean reentry. So it's been stuck in a chaotic orbit for 18 months, getting pulled around by both bodies' gravity until it wound up on a collision course.

Bill Gray at Project Pluto has been refining the trajectory using over 1,000 observations from asteroid surveys and amateur astronomers. His current prediction puts the impact at 06:34 UTC on August 5, give or take a few seconds. The stage weighs roughly 4,900 kg and will hit at 2.43 km/s, around 5,400 mph, releasing energy equivalent to about 3 tons of TNT. That should dig a crater roughly 17 meters across near Einstein Crater, on the Moon's sunlit western limb.

That "sunlit" part matters if you're hoping to watch. Impact flashes are easiest to spot against the dark side of the Moon, and this one lands on the bright face, so catching the flash from the ground will be extremely hard. The ejecta plume is more promising: if the debris column rises high enough, orbiting spacecraft might capture it. NASA's Lunar Reconnaissance Orbiter and South Korea's Pathfinder Lunar Orbiter will image the site before and after. A crater from a known impactor mass and speed is useful for testing impact models, though we already have data from deliberate impacts like LCROSS, so the science here is more incremental than the headlines make it sound.

Worth remembering we've been here before and gotten the story wrong. In 2022, a spent rocket stage hit the Moon and was widely reported as a Falcon 9 from the 2015 DSCOVR launch. It turned out to be a Chinese Chang'e 5-T1 booster from 2014, and that correction took months. The tracking this time is far better documented, with over a thousand independent observations, but predicting the exact behavior of a tumbling piece of debris under solar radiation pressure still carries real uncertainty in the final kilometers.