LONG BEACH, CA — A discarded SpaceX rocket stage is expected to slam into the moon on Wednesday after spending more than a year drifting through space.
The Falcon 9 upper stage, which launched two private lunar landers in January 2025, is predicted to strike the moon at roughly 5,400 mph. The impact is expected to occur near Einstein Crater on the moon's western limb, carving out a new crater and sending a plume of dust and rock into space.
Scientists say the collision poses no danger to Earth but offers a rare opportunity to study how impacts affect the lunar surface. NASA's Lunar Reconnaissance Orbiter and South Korea's Danuri lunar orbiter are expected to capture images of the impact site before and after the crash.
The impact flash, lasting less than a second, will probably be too dim to see, according to experts. But the stream of ejected material could stretch for several miles (kilometers) into space and remain visible to telescopes for tens of minutes.
"The gravity on the moon is low and there is no wind to blow the dust away," said Los Alamos National Laboratory's Benjamin Fernando, who's encouraging observations by professionals and amateurs alike.
"Part of the reason for our interest in this event is to figure out how much of a hazard debris impacts pose to future astronauts," he added in an email.
Fernando anticipates an impact crater nearly 90 feet across and 16 feet deep (27 meters across and 5 meters deep), too small to see from Earth but visible to spacecraft.
The current prediction for time of impact is approximately 06:35 UTC on Wednesday, August 5, 2026 (11:35 p.m. PDT on Tuesday, August 4), according to astronomer Bill Gray and a recent observational planning paper led by Benjamin Fernando.
The rocket stage was not intended to hit the moon. Experts said that the impact could have been avoided had the spent upper stage been directed into an orbit around the sun after completing its mission.
The abandoned rocket segment — measuring some 40 feet (12 meters) and weighing around 10,000 pounds.
The Falcon 9 upper stage launched Firefly Aerospace's Blue Ghost lunar lander and an ispace lunar lander on January 15, 2025. Blue Ghost later completed a successful lunar landing while the ispace mission ended unsuccessfully.
With the moon as the new travel hot spot, scientists said it's crucial to improve debris monitoring and traffic control before packs of robots and astronauts arrive.
The event also highlights the growing challenge of managing space debris as activity around the moon and in Earth orbit continues to increase. Researchers say observations from the impact could help scientists better understand the risks debris poses to future lunar missions and astronauts.
"Things are getting crowded up there," Space tracking expert Bill Gray said.
The United States and China are racing to land astronauts on the moon in the next few years. Elon Musk's SpaceX and Jeff Bezos' Blue Origin are vying to provide the lander for NASA's yet-to-be-named moonwalkers of Artemis IV, who will succeed the 12 Apollo astronauts who strolled the lunar surface.
"This impact will not be a problem," retired astrophysicist Jonathan McDowell said in an email. "But in a future where there are long-term bases on the moon, similar impacts would be an issue and we need not to leave rocket stages in chaotic orbits of this kind."
MARCIA DUNN AP Aerospace Writer contributed to this report.
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