Spent SpaceX Falcon 9 Upper Stage Predicted to Strike Moon; Plume Might Be Visible

A spent SpaceX Falcon 9 upper stage is expected to slam into the moon within hours, and a new scientific preprint suggests the impact could kick up a plume bright enough to be visible from Earth, at least briefly.

If the prediction holds, the event would offer a rare chance to watch an artificial lunar impact in near real time. For scientists, that makes it more than a space-debris footnote: Because researchers know the incoming object’s approximate mass and speed, the crash could help test impact models and reveal how lunar soil responds when struck. The best-known precedent is NASA’s LCROSS mission in 2009, which deliberately crashed hardware into the moon and studied the resulting plume for signs of water. This impact is accidental, but it presents a similar observation opportunity.

The object is a spent Falcon 9 upper stage catalogued as 2025-010D and NORAD 62719. It came from the Jan. 15, 2025, Falcon 9 launch that carried Firefly Aerospace’s Blue Ghost-1 and ispace’s HAKUTO-R Mission 2, also known as Resilience.

Independent tracker Bill Gray, who runs Project Pluto, published the impact prediction, and later papers and tracking efforts have converged on the same Aug. 5 scenario. Project Pluto’s current best estimate puts the impact at 06:34:32.9 UTC, with the stage expected to hit near the lunar limb, close to Einstein Crater, at about 19.455 degrees north latitude and 266.406 degrees east longitude.

The modeling assumes an impact speed of about 2.43 kilometers per second and a stage mass of about 3,900 kilograms.

The new observability study, by Jo and colleagues, was posted on arXiv as preprint 2607.23904v2 and has not been peer reviewed. It models the crash as capable of producing an ejecta curtain — the sheet of material thrown outward by the impact — rising roughly 15 to 20 kilometers, along with a central ejecta spike reaching about 75 to 100 kilometers. The plume could spread laterally about 183 kilometers from the impact point.

According to the authors, the simulated brightness in the first minutes after impact exceeds the dark-sky background by orders of magnitude. They report a reflectance value, or I/F, of 1.27×10^-3 just five seconds after impact, suggesting that sunlight on the lofted debris could make the plume stand out despite the moon’s bright surface.

That geometry is part of why researchers are interested. A separate observational-planning preprint by Fernando and colleagues called for coordinated observations by professional and amateur observers because the stage is expected to hit sunlit terrain near the lunar limb, where a plume may be easier to detect against the background.

But visibility is far from guaranteed. Jo and colleagues modeled a near-vertical, engine-first impact by a propellant-exhausted stage, and they note that a different orientation could change the structure and brightness of the ejecta. The predicted impact time and location also have been refined through tracking and could still shift by seconds or small distances.

Some experts are cautious about what Earth-based observers might actually see. William Cooke of NASA’s Meteoroid Environment Office told Space.com, “I think it's going to be very subtle. I think it's going to be very, very hard to see, if not impossible. But there's always a chance,” Cooke added, “It will excavate that out of the crater and this may create a plume that will be illuminated by the sun.”

Even with those uncertainties, scientists are treating the event as a real observing opportunity. Coordinated campaigns are planned around the expected impact time, and NASA’s Lunar Reconnaissance Orbiter is expected to image the site before and after the crash to search for a fresh crater.