A fresh look at the available evidence suggests a Chinese booster will smash into the Moon in early March—and not a SpaceX Falcon 9 second stage as was previously believed. Experts say it’s an “honest mistake” and a sign that better processes are needed to track our junk in space.
We first reported on this story in late January, as did many other media outlets. That a SpaceX Falcon 9 booster was on a collision course with the Moon attracted widespread attention, including a live webcast to capture our final view of the discarded booster. A safety expert with the European Space Agency also chimed in, saying the “upcoming Falcon 9 lunar impact illustrates well the need for a comprehensive regulatory regime in space.”
All this fuss, it turns out, was directed at the wrong object. Bill Gray, developer of Project Pluto, a software program for tracking near-Earth objects, asteroids, comets, and other things in space, now says it’s a Chinese booster from the Chang’e 5-T1 mission and not a Falcon 9 booster as he told the world last month. It’s a regrettable mistake, but also understandable, given the ad hoc manner in which such objects are identified and catalogued.
As Gray details in his corrections notice, it was Jon Giorgini, a scientist with NASA’s Jet Propulsion Laboratory (JPL), who first alerted him to the possible error. JPL isn’t in the business of tracking space junk, but it does track active spacecraft, including the Deep Space Climate Observatory (DSCOVR) mission, which launched to space seven years ago atop the implicated Falcon 9 rocket. Giorgini informed Gray that DSCOVR’s trajectory was nowhere near the Moon, so the booster was very unlikely to hit the lunar surface.
This prompted Gray to go back and check his results, as he had originally identified this object as being a Falcon 9 booster back in 2015. Astronomers with the Catalina Sky Survey had originally detected the unidentified object, giving it the placeholder designation WE0913A. Gray looked into it shortly thereafter, concluding that it was very likely related to NOAA’s DSCOVR mission. As he wrote on Saturday:
Further data confirmed that yes, WE0913A had gone past the moon two days after DSCOVR’s launch, and I and others came to accept the identification with the 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.
Essentially, I had pretty good circumstantial evidence for the identification, but nothing conclusive. That was not at all unusual. Identifications of high-flying space junk often require a bit of detective work, and sometimes, we never do figure out the ID for a bit of space junk; there are a couple of unidentified bits of junk out there. (At least, not identified yet.)
With the Falcon 9 booster ruled out, Gray looked at earlier space missions that might explain the object, leading him to a booster from the Chang’e 5-T1 mission. The associated Long March 3C rocket launched on October 23, 2014, in which a small spacecraft was sent to the Moon in preparation for a future lunar sample return mission.
Gray provided the associated evidence, but “in short, it looks exactly like a Chinese lunar mission ought to look in every particular,” he wrote. Jonathan McDowell, an astronomer from the Harvard-Smithsonian Center for Astrophysics, provided further evidence in the form of orbital data related to a radio cubesat that went along for the ride. With this combined data, “I am persuaded that the object about to hit the moon on 2022 Mar 4 at 12:25 UTC is actually the Chang’e 5-T1 rocket stage,” wrote Gray.
McDowell described it as “an honest mistake” in a tweet, saying the incident “emphasizes the problem with lack of proper tracking of these deep space objects.” I reached out and asked him to elaborate.
“Well, a good start would be for some official organization with money—NASA or ESA perhaps, or the UN COPUOS [the Committee on the Peaceful Uses of Outer Space]—to decide that this was something that needed doing,” McDowell responded in an email. “And then hire at least one person to do it, or parts of several people.”
He’d also like to see a UN recommendation in which countries make their deep space orbital data (i.e. last known state vector) publicly available for their space junk. This data, McDowell said, could be submitted directly to the UN, for example.
The Long March 3C booster doesn’t endanger life or equipment, but McDowell’s point is well taken—we need to know what’s out there and who it belongs to. Accountability matters, especially now that we’re launching more rockets into space than at any other time in history. Which reminds me, there’s still a discarded Falcon 9 booster floating somewhere in space. Rumors of its pending death were greatly exaggerated, so we may have not heard the last.