A discarded SpaceX Falcon 9 upper stage from a January 2025 launch of Firefly Aerospace's Blue Ghost and ispace's Hakuto-R missions is expected to strike the moon early Wednesday morning (Aug. 5), raising questions about whether skywatchers will be able to see the collision or its ejecta plume from Earth.
What Happened
The 45-foot-long (13.8-meter), 8,000-pound (4,000-kilogram) rocket stage is traveling at roughly 5,400 mph (8,700 km/h) and will impact near the moon's western limb close to Einstein Crater on the Earth-facing side. While the collision itself is unlikely to be visible from Earth because any flash would be washed out by the bright lunar surface, material blasted high above the horizon could form a faint plume against the darkness of space. Recent simulations suggest the central ejecta plume could climb as high as 60 miles (100 kilometers), though whether it will be detectable from Earth remains uncertain.
"Maybe we'll see the flash. Maybe we'll see rocks ejected from the crater. Maybe we'll even see both," astronomer Bill Gray, who first identified the rocket stage's eventual lunar collision, wrote on his Project Pluto website. Observers along the U.S. East Coast will have a low viewing angle — the moon sitting only about 40 degrees above the southeastern horizon before dawn — while parts of South America may get more favorable views with the moon higher in the sky.
Regardless of Earth-based visibility, several spacecraft will be watching from closer vantage points. South Korea's Danuri lunar orbiter is expected to observe the impact in real time, and NASA's Lunar Reconnaissance Orbiter (LRO) will photograph the site before and after to measure the newly formed crater and compare it with other human-made impacts on the moon.
Why It Matters
The accidental crash represents a valuable scientific opportunity. Unlike natural meteoroids, the hollow aluminum rocket stage will strike the moon with well-known size, mass and velocity, giving scientists a rare chance to test models of how impacts excavate lunar material and create craters. The observations could also help researchers better understand hazards posed by space debris as both crewed and robotic missions to the moon become increasingly common.
The Bottom Line
A Falcon 9 upper stage is set to hit the moon near Einstein Crater on Aug. 5, with orbiters poised to capture the event even if Earth-based skywatchers may not see it. The unintended collision turns into a controlled experiment for lunar impact science and space-debris risk.