Space is very, very big, and it is mostly empty. Occasionally, though, two
objects will find themselves occupying the same space at the same time. This is perhaps best demonstrated every summer around Aug. 12 when thousands of dust particles from a comet try to occupy the space that the Earth is in, and Earth inevitably wins.
This week, though, in the early-morning hours of Wednesday Aug. 5, a very different kind of interaction will take place. At around 2:35 a.m. EDT the moon and a spent SpaceX Falcon 9 upper stage will meet, and while the moon will undoubtedly win the tilt, the Falcon may just put up a fight that could be visible here on Earth.
The Falcon 9 launched a pair of lunar probes on Jan. 15, 2025: Firefly
Aerospace’s Blue Ghost lunar lander and the Japanese Hakuto-R Mission 2 lunar lander, with the spent rocket stage also following a trans-lunar trajectory.
After over a year in the moon’s vicinity, the rocket will finally impact it.
The moon has been hit by a variety of manmade space hardware since 1959, when the Soviet probe Luna-2 was intentionally sent to impact as a demonstration of Soviet space capabilities. Spent upper stages of Saturn V rockets were steered to lunar impact to calibrate seismometers left by Apollo astronauts, and other orbital probes were sent to lunar impact to keep the space around the moon from accumulating “space junk.”
So why the fuss over this particular event? Because it may be visible to observers here on Earth. The stage will impact just over the visible limb of the moon, near the crater Einstein. The moon’s limb will be bright, as the phase is near last quarter.
Odds are that nobody will see the impact itself, but it’s possible that sunlight scattered by the cloud of debris excavated by the hit might be visible by telescope shortly after the predicted time, and may persist for several minutes.
The Falcon 9 upper stage has a mass of 8,800 pounds and will hit the moon at a velocity of 5,400 mph. The amount of energy that will be released is equivalent to about 3 tons of TNT, and will likely blast about 2.2 tons of material some 100 to 200 miles above the lunar surface. The resulting crater may be over 50 feet across.
Observers along the U.S. East Coast and most of South America will have
the best chance to see the event. Hopefully some observers will have clear skies and see something that has never been seen from Earth before!
For a more details on this impact event, visit the Project Pluto website:
https://www.projectpluto.com/25010d.htm
