The debris is set to collide with the moon next month. It may not be a SpaceX rocket as previously thought.
Astronomers discovered last month that a piece of debris was about to crash into the Moon in less than three weeks. It was originally thought to be part of alaunched in 2015 – but closer examination of the object revealed a potentially different story.
Bill Gray, who writes Project Pluto software for astronomers, revealed in late January that a piece of debris would have “some impact” with the far side of the moon on March 4. Gray originally thought the debris in question, which he began tracking in March 2015, is an old Falcon 9 stage that was left in orbit after the rocket launched weeks before its tracking began.
But over the weekend, Gray said he received an email from Jon Giorgini of the Jet Propulsion Laboratory, which tracks active spacecraft. Giorgini, Gray said, had questioned the claim that the SpaceX piece had passed the moon closely two days after the rocket launched.
“Jon pointed out that JPL’s Horizons system showed that the trajectory of the DSCOVR spacecraft did not go particularly close to the moon. It would be a little strange if the second stage passed right in front of the moon, when DSCOVR was in a other part of the sky ” Gray Explain. “There’s always some separation, but this one was oddly big.”
So, he said, he dug into his records to figure out what had happened.
After reviewing the data, he realized that what he thought was a piece of the SpaceX rocket was actually the propellant for the Chang’e 5-T1 lunar mission, which would have been close to the moon at the era he thought SpaceX stage had. Another astronomer, Jonathan McDowell, also sent Gray data that seems to support the conclusion.
“In a sense, it’s still ‘circumstantial’ evidence. But I would consider it pretty compelling evidence, the kind where the jury would walk out of the courtroom and be back in a few minutes with a conviction,” Gray said.
The booster continues to be in a “chaotic” orbit as it floats away from Earth and outside the moon’s orbit, and is still officially set to collide on March 4. However, Gray said he had received “quite a lot of data” since his initial projection and now expects the booster to land “a few miles east and seconds ahead of” his original prediction.
“Not much change, in other words,” he said.
And regarding the SpaceX booster, Gray says he’s not sure where it is, but thinks it may have ended up orbiting the sun.