BOWDOINHAM, MAINE — The rocket part crashing toward the Moon is not the upper stage of a SpaceX Falcon 9, as was suggested by astronomers last month, rather it is most likely to be part of the Long March 3C rocket that launched China's moonbound Chang'e 5-T1 mission in October 2014.
Astronomer Bill Gray, who originally identified unknown object WE0913A as a Falcon 9, published a correction on his Project Pluto blog on Saturday after receiving a note from Jon Giorgini, an engineer at NASA's Jet Propulsion Laboratory.
Giorgini said that the original trajectory of the SpaceX rocket did not go especially close to the moon when it launched the NOAA’s Deep Space Climate Observatory to the Lagrange Point 1 in 2015, and thus it would be “a little strange if the second stage strayed close enough to strike it.” Confirming the misidentification, Gray explained he and other researchers found that WE0913A went past the moon two days after the NOAA’s Deep Space Climate Observatory launch and had wrongly believed that the timing, the object’s brightness, and a ‘reasonable orbit’ made it a match.
He added that he had originally explained some apparent strangeness in the object’s early orbit compared to what was known about the NOAA’s Deep Space Climate Observatory’s launch by assuming it was caused by rocket fuel leaking out and altering its trajectory.
Now, having re-analysed data of launches around the same time, the booster from China's Chang'e 5-T1 mission has been found to have an initial ‘high orbit going past the moon’ that makes it the more likely candidate to be the object colliding with the Moon on March 4, though Gray points out that the evidence remains necessarily circumstantial.
In 2014, the Chang'e 5-T1 mission sent a test capsule to slingshot around the moon and return to Earth in preparation for 2020’s Chang'e 5 mission, which involved a robotic lunar sample return.
