Progression

A four-ton SpaceX Falcon 9 upper stage left drifting after a 2025 lunar mission is expected to crash into the Moon at about 5,400 mph, likely striking Einstein Crater. The impact should occur at approximately 2:35 a.m. ET (0635GMT). Reuters reports: Such stages typically fall back into Earth's atmosphere and burn up or plunge into the ocean after boosting the rocket's payload to a precise spot in orbit. But because the January lunar lander mission required more thrust than missions closer to Earth, the rocket's second stage remained in space, floating aimlessly among thousands of other pieces of space junk that active satellites must steer clear of. It was not until earlier this year that astronomers determined that the rocket stage, which had dumped its remaining fuel and cannot be controlled, was on an orbital trajectory ending at the moon.

"What has happened is essentially a mixture of solar activity and gravity forces have put it on a path toward the moon," Julianna Scheiman, SpaceX director of NASA science and Dragon programs, told reporters on Monday. "This may be of some -- probably minor -- scientific interest, and we may learn some things from it," said Bill Gray, creator of widely used astronomy software who published a report on the stage's impact in April. "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." You can try to watch the impact via a livestream on YouTube; however, the area it's expected to hit (Einstein Crater) is on the moon's western limb, "which is often difficult to see from Earth," notes Reuters. It will also likely "kick up a plume of lunar dust that will likely be illuminated by sunlight but difficult to spot with the naked eye from Earth."