A spent SpaceX Falcon 9 upper stage is forecast to slam into the moon near Einstein Crater early Wednesday morning, potentially producing the first impact plume observed from Earth against the lunar surface's sunlit side.
William Jo, a doctoral candidate at the University of Texas at Austin's Cockrell School of Engineering, and five co-authors posted a preprint to arXiv detailing the expected lunar impact of the spent upper stage rocket.
Using a high-resolution physics simulation, the researchers modeled what could happen when roughly 3,900 kilograms of hollow rocket hardware slams into the lunar surface:
On Aug. 5 at 06:34 UTC, a Falcon 9 upper stage (~3,900 kg) will strike the lunar surface at 2.43 km/s, yielding a potentially visible debris plume.
We present a study of the expected impact dynamics and resulting possibly observable debris field. The debris plume should reach roughly 15 to 20 km in altitude for the ejecta curtain and 75 to 100 km for the central ejecta spike, extend 183 km laterally from the impact point near the sunlit limb, and yield a peak dust column density above 10 km altitude of 6.08*10^7 m^-2.
Simulated I/F exceeds dark-sky background brightness by several orders of magnitude for the first few minutes after impact, reaching I/F = 1.27*10^-3 at the earliest resolved time (t = 5 s). Above 10 km, peak I/F reaches 1.33*10^-5, still several orders of magnitude brighter than the dark sky.
NEWS 🚨: A Falcon 9 upper stage abandoned in orbit since Jan. 2025 will hit the Moon on August 5 at ~5,437 mph (8,750 km/h)
— Latest in space (@latestinspace) July 29, 2026
It's projected to carve out a 100-foot crater pic.twitter.com/20hOVAhsVv
Jo and the other researchers hope the unplanned collision next week will provide insight into lunar geology and the risks posed by discarded rockets as the US, China, and private companies plan future moon bases.
