An astronomer and space tracking expert created a bit of a splash last month when he predicted that a component of an old SpaceX Falcon 9 rocket that had been left in space for the last seven years will collide with the Moon this March. But he’s now drastically altering that projection. While the rocket part he’s been tracking is still on a collision course with the Moon, he now believes the vehicle is an old Chinese rocket rather than an old Falcon 9 part.
Bill Gray, an astronomer and asteroid tracker who has been watching this doomed object since March of 2015, provided the update. According to him, the object was discovered by the Catalina Sky Survey, a program that uses telescopes in Tucson, Arizona, to search the sky for potentially deadly asteroids that could pose a threat to Earth. When the survey discovered this object, other scientists noted that it wasn’t orbiting the Sun like asteroids usually do. It was actually orbiting the Earth, implying that the object was man-made and that we sent it into space ourselves.
Several clues led Gray and others to believe that the item was one of SpaceX’s rockets. They believed it was the top half of a Falcon 9 rocket that had flown in February 2015, launching a valuable satellite named DSCOVR into a very distant orbit for the National Oceanic and Atmospheric Administration. That rocket would have traveled to a very high altitude to deliver the satellite to its target, and this newly discovered object appears to have passed by the Moon two days after the DSCOVR mission launched. Gray and others were quite certain that the mystery trash was part of the Falcon 9 rocket that launched DSCOVR based on those details and other characteristics of the object.
However, Gray concedes that identifying objects like this isn’t always as straightforward as we’d like. « I had reasonably good circumstantial evidence for the identification, but nothing conclusive, » Gray said in a new blog post, which Ars Technica first reported on.
Since Gray projected in January that the deep-space object will collide with the Moon on March 4th, this object has gotten a lot of attention. Gray is very certain that this object is a remnant piece of a Chinese rocket, namely a Long March 3C that launched China’s Chang’e 5-T1 mission to the Moon, after taking a deeper look at the object’s history and receiving some new facts from NASA. That flight was a test mission that sent a capsule circling around the Moon and careening back to Earth to test out the technology China would use to send samples of lunar material back to Earth.
Gray claims he discovered the incorrect identification after he received an email from someone at NASA’s Jet Propulsion Laboratory who keeps track of active space missions. JPL has its own tracking system, and the JPL employee stated that the Falcon 9 passing near to the Moon two days after the DSCOVR launch was improbable. « He had the thought, ‘Wait a minute. « I don’t recall going past the Moon, » Gray tells The Verge. « This prompted him to investigate the previous data on where DSCOVR actually went. » Based on the track of that flight, the Falcon 9 would have been in a different portion of orbit when this object passed over the Moon.
So Gray went back in time to see if there were any other launches that may be a good match for this item. That’s when he came across the Chang’e 5-T1 mission, which launched in October 2014. He discovered that the Long March 3C rocket that launched the mission is currently the best fit for this mystery item after reconstructing the mission’s probable orbit and trajectory.
« I think we can conclude we have a very strong chain of evidence, » Gray says. « It makes perfect sense to run the orbit back to launch for the Chinese mission. » It ends up with an orbit that takes it past the Moon shortly after launch. »
Despite the uncertainty surrounding the object’s identity, Gray thinks it’s only further evidence that we need to learn more about these deep-space rocket boosters. As Gray points out, some people believe that because these items are so far out in orbit, we don’t need to pay attention to them once they’re in space. As of yet, no institutional entity is routinely following leftover rockets like this that travel into outer space. « The only people I know who are interested in these vintage rocket boosters are the asteroid tracking group, » he explains.
Gray believes that it would be preferable if individuals who launch deep space rockets were required to record the last known location of their vehicles, making it easier to trace and identify lost parts. Of course, China is known for withholding details about its space endeavors. « This type of thing would be a lot easier if the people who launch satellites had to disclose something, » Gray says. « However, as things stand, there’s always a certain bit of detective work involved in figuring these things out. »