A piece of space junk expected to slam into the moon on March 4, previously suspected of belonging to a SpaceX Falcon 9 rocket, is now thought to be an errant chunk of Chinese rocket launched in 2014.
The case of mistaken identity was announced on Saturday on the Project Pluto website by Bill Gray, an astronomer, and manager of the Project Pluto software used to track near-Earth objects, according to News 6 partner Florida Today. Gray had originally announced the lunar collision potential on the Project Pluto website about three weeks ago.
In February 2015, a SpaceX Falcon 9 rocket launched the National Oceanic and Atmospheric Administration Deep Space Climate Observatory (DSCOVR) satellite from Space Launch Complex 40 at the Cape Canaveral Space Force Station. A month later, astronomers identified what was initially thought to be a possible near-Earth asteroid that had zoomed past the moon just two days after the SpaceX launch.
Gray, with others, preliminarily identified the object as a stray piece of the Falcon 9 rocket that launched the DSCOVR spacecraft.
“I and others came to accept the identification with the (Falcon 9) second stage as correct. The object had about the brightness we would expect, and had showed up at the expected time and moving in a reasonable orbit,” stated Gray in Saturday’s post on the Project Pluto website. “Essentially, I had pretty good circumstantial evidence for the identification, but nothing conclusive.”
An email by Jon Giorgini, an engineer at NASA’s Jet Propulsion Laboratory, received by Gray on Saturday morning suggested that the object most likely couldn’t be that of the Falcon 9 rocket.
Giorgini explained that the spacecraft’s trajectory had not taken it anywhere particularly close to the moon. For the rocket’s second stage to end up so far away from the spacecraft itself would have been very unusual.
Gray originally suspected that the SpaceX rocket hardware could’ve ended up in the lunar neighborhood due to erratic leaking of leftover fuel. But, he admits in the post that, “Assuming no maneuvers, it would have been in a somewhat odd orbit around the earth before the lunar flyby,” and likely would not have ended up near the moon when the object was originally observed.
Prompted by Giorgini’s email, Gray dug further into previously collected data looking for what other launches could have produced a piece of space junk that could now line up for a slam dunk with the moon.
The most likely candidate turned out to be a piece of a Chinese Long March 3C rocket. The rocket launched China’s moonbound Chang’e 5-T1 mission in October 2014.
This identification matches up better with the object that flew past the moon in 2015. “It’s unclear when the Chang’e 5-T1 booster would have gone by the moon, but four days after launch would be a reasonable ballpark estimate,” Gray said.
The claim was provided further merit by fellow space debris tracker, Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, who identified a small “cubesat” that was launched on the same Chinese rocket.
“In a sense, this remains “circumstantial” evidence. But I would regard it as fairly convincing evidence,” Gray concluded.
He concluded that whatever it was, “had to have been launched not long before March 2015, in a high orbit going past the moon. Few objects go that high; most stay relatively near the earth.”