GoKawiilAn astronomy software dev claims a Falcon 9 upper stage will hit the Moon in August, traveling at several times the speed of sound.
The upper stage of the Falcon 9 rocket used to launch the Blue Ghost and Hakuto-R lunar lander is set to have its own close encounter with the Moon after loitering in orbit for more than a year, claims astronomer Bill Gray of Project Pluto, who posted a commentary on the object. It is his software that projected the August 5 impact.
The Falcon 9 was launched on January 15, 2025, on a mission to send a pair of landers to the Moon. One, Firefly Aerospace's Blue Ghost, made a successful landing. The other, ispace's Hakuto-R, did not fare so well.
However, while the first stage of the Falcon 9 landed successfully, the second stage and payload canister remained in space. The latter reentered the atmosphere and was destroyed. The former was in too high an orbit and carried on circling the Earth. Too high for the US military's tracking service to get an accurate fix, but detectable by amateur astronomers and asteroid surveys.
Gray notes in his post that: "It doesn't present any danger to anyone, though it does highlight a certain carelessness about how leftover space hardware (space junk) is disposed of."
The object, dubbed 2025-10D is - according to Gray - in an "orbit around the Earth, taking about 26 days to go around us. The orbit is lopsided; at its closest (perigee), the object is about 220,000 kilometers (137,000 miles) away. At its farthest, it gets out to 510,000 km (310,000 miles). For comparison, the moon is about 385,000 km (240,000 miles) away.
"The orbit of the Moon and of this object, roughly speaking, intersect. Usually, one goes through the intersection point while the other is someplace else. But on August 5, they'll reach that point at the same time."
As for its speed when it hits the lunar surface, Gray said:
2.43 kilometers a second, or 1.51 miles a second, or 5,400 miles an hour, or 8,700 kilometers an hour. There is, of course, no air and no sound on the Moon, so a "Mach number" doesn't really make sense. But if there were air, the speed would be about Mach 7, seven times the speed of sound.
There is very little risk from the impact – there are no humans on or around the Moon, and it is highly unlikely debris from the upper stage will strike probes in the vicinity. Will it be visible? "Probably not."
... continue reading