The lunar far side as imaged by NASA’s Lunar Reconnaissance Orbiter using its LROC Wide Angle Camera.
Credit: NASA/Goddard/Arizona State University


There’s an on-going saga regarding what object will smash into the Moon’s far side next month.

First thought to be a SpaceX upper stage, it was then tagged as a leftover from China’s Chang’e 5-T1 lunar mission in 2014.

But China has indicated it’s not their hardware, a flat fact coming from Foreign Ministry Spokesperson Wang Wenbin’s in a regular press briefing on February 21st.

However, sticking to his guns about identifying the object as related to the Chang’e 5-T1 mission is Bill Gray of Project Pluto.

“There really is no good reason at this point to think the object is anything other than the Chang’e 5-T1 booster. Anybody claiming otherwise has a pretty large hill of evidence to overcome,” Gray told Inside Outer Space.

Small mystery

“We do have a small mystery, in that the [U.S.] 18th Space Control Squadron lists this booster (the same one I’m saying will hit the Moon) as having instead hit the Earth’s atmosphere in October 2015, almost a year after launch,” Gray explains. “But the only trajectory data they provide are for shortly after launch. If that’s all they had to work with, then the re-entry date is a prediction a year ahead of time and is not particularly meaningful.”

18th Space Control Squadron logo
Credit: 18th Space Control Squadron

It’s sort of like trying to predict weather a year ahead of time, Gray adds.

Re-entry computation

“But as best I can tell, this particular error didn’t involve tracking data,” he tells Inside Outer Space. “I think it just involved confusion about two similarly named missions,” China’s Chang’e 5-T1 mission in 2014 and the country’s Chang’e-5 Moon sample effort in December 2020.

“Basically, I don’t think 18SPCS tracked the object much after launch,” Gray says. “If they had, they probably would have posted updated trajectory data. If the re-entry computation is based on just that initial tracking data, with no further observations taken into account, it’s not going to be any good. You can’t run an orbit for an object of this sort out a year and get anything meaningful.”

Also, during much of that year, the Chang’e-5T1 booster would have been well beyond the range of radar. “So I very much doubt 18SPCS were actually tracking it. But asteroid observers did keep track of it several times over that year, and in the years afterward, such that I was able to say it would hit the Moon in March,” Gray says.

Off the hook? Artist’s impression of DSCOVR on the way to L1 atop its Falcon 9 upper stage in 2015.
Credit: SpaceX

Wanted: better tracking

All of this confusion raises a flag in Gray’s view.

“Well, we should indeed do a better job of tracking these objects. First step would be to release ‘last known positions and velocities’ for objects going into high Earth orbits or solar or lunar orbits. That would have avoided the initial identification issue, where I thought this was the [SpaceX] DSCOVR upper stage.”

Bottom line for Gray is the need for better tracking of high-orbiting objects.

NASA looksee

NASA Lunar Reconnaissance Orbiter (LRO).
Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab

Meanwhile, NASA’s Lunar Reconnaissance Orbiter will monitor the Moon’s exosphere for any changes due to the March 4th impact, and looking for the crater in the months to come.

According to a NASA statement provided to Inside Outer Space:

“NASA’s Lunar Reconnaissance Orbiter will not be in a position to observe the impact as it happens. However, the mission team is assessing if observations can be made to any changes to the lunar environment associated with the impact and later identify the crater formed by the impact. This unique event presents an exciting research opportunity. Following the impact, the mission can use its cameras to identify the impact site, comparing older images to images taken after the impact. The search for the impact crater will be challenging and might take weeks to months.”

According to one researcher, “a pizza is still a pizza, even if you don’t know where it came from.”

For more information on this upcoming, smashing event, go to:

  • March Madness! Upper Stage Hitting the Moon: Will the Real Owner Please Stand Up?

  • The Case of the Wayward Booster Headed for the Moon

  • SpaceX Upper Stage: Hitting the Moon Update

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