It’s been a bit of an up-and-down month for SpaceX, Elon Musk’s rocket ship and satellite internet company.
The bad news: A solar storm sent 40 of its Starlink satellites plunging back to Earth. They’ll burn up in the Earth’s atmosphere, costing the company as much as $100 million and casting fresh doubts on Musk’s big plans for the satellite internet on top of those recently expressed by China and NASA. The good news? All of those reports that a SpaceX rocket was about to crash into the moon were wrong: The rocket belongs to someone else.
The error highlights the growing problem of all the junk we, as a planet, shoot into space and how we deal with it (or not, as the case may be). Not everything we send up comes down, and some of it gets lost. That’s especially true once it leaves Earth’s orbit because there’s no one officially tracking our space litter out there. Basically, we’re leaving it up to a handful of dedicated astronomers who do it as a hobby.
One of those astronomers is Bill Gray. He developed software called Project Pluto, which is used to track objects in space. A few weeks ago, he announced that part of a SpaceX Falcon 9 rocket would crash into the moon on March 4. Numerous news stories followed (Musk-related disasters tend to grab headlines), but any hopes that Musk would get knocked down a peg came crashing back to Earth a few days ago. Gray announced that he made a mistake: The wayward object is most likely the booster for China’s Chang’e 5-T1 rocket, which was launched in 2014.
Perhaps surprisingly, this case of mistaken identity isn’t hard to make, even for the relatively few people who track these kinds of things all the time. Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, explained that it’s difficult to pinpoint an uncontrolled object’s exact path through space. There are plenty of variables out there that can change the object’s trajectory, and even a small change adds up over time and distance.
Also — and this is the heart of the problem — we aren’t really tracking these things anyway.
We have a good idea of what’s orbiting the Earth, especially if those objects are sending signals back to us or if they’re in a position to endanger anything or anyone in Earth orbit (or on the Earth itself). And we know where important scientific things like space telescopes, deep space weather satellites, and probes are.
But a piece of space debris — a discarded rocket stage, let’s just say — floating around well beyond Earth’s orbit is more of a curiosity than a concern. Since there aren’t any rules for tracking the stuff we launch into deep space, the only information we may have to go on is launch data and observations from astronomers who happen to catch it on its merry way across the night sky, assuming it’s even close enough to be visible.
The rocket mix-up happened years ago, Gray told the New York Times. He computed the orbit of an object first observed in March 2015 and found that it had passed the moon about a month earlier. That matched with what he believed was the flight path of a recent SpaceX launch, so Gray was fairly certain the object was a discarded rocket booster from that launch.
It was only after he announced that a SpaceX rocket was going to crash into the moon that he realized it wasn’t launched toward the moon at all, so it likely wasn’t the object. But China’s Chang’e 5-T1 rocket launched in October 2014 was sent toward the moon, making it the new (and current) most likely suspect. Also helpful, McDowell said: An amateur radio satellite from Luxembourg hitched a ride on that rocket booster, providing several days of orbital data. Once the SpaceX rocket was ruled out, they realized they were likely looking at the Chinese rocket instead.
If this all seems like a disturbing amount of guesswork, fortunately, when it comes to stuff that could crash into the Earth, we’re a little more diligent. Self-interest, along with the knowledge of what likely happened to the dinosaurs, is a powerful motivator. Which is why, since 1998, NASA has been operating the Center for Near-Earth Object Studies, which tracks potentially hazardous objects so we can identify and, if necessary, stop collisions that would otherwise be catastrophic. More specifically, the center watches for asteroids and comets that are large enough and will pass close enough to our planet — less than 4.6 million miles is considered “close” — to pose a potential threat to it.
Other than that, NASA told Recode that it’s really in the business of tracking space debris only when that debris could endanger NASA’s assets. The Center for Near-Earth Object Studies did end up helping to figure out who the rocket likely belongs to, but that was only in response to the attention it got over its impending demise. The United States Space Force also tracks orbital debris but didn’t respond to request for comment on if or how it tracks debris in lunar orbit.
“Things that are more than, say, 100,000 kilometers up? Space Force doesn’t care,” McDowell said. “It’s a sufficiently small amount of traffic. There’s not really a risk of them hitting each other.”
This won’t be the first time a man-made object has crashed into the moon. While purposely crashing objects into planetary bodies seems more in the fictional realm of a James Bond villain, Cobra Commander, or George Méliès, it does happen. Last November, NASA launched a rocket into an asteroid to see if we can push asteroids off course if one ever threatens to hit Earth. And, in 2009, NASA threw a rocket into a moon crater to see if there was any water in the crater. And there are several more missions to various planets from multiple countries that end with the spacecraft crashing into the bodies they’re orbiting after they run out of fuel or complete their missions.
Unintentional crashes are rarer, but we had a fairly recent example back in 2019, when an Israeli company’s moon mission ended with the lander crashing, possibly spilling on its surface the thousands of tardigrades that were along for the ride. Oops. Prior to that, we hadn’t had an accidental moon crash since 1971. At least, not one that we know of.
“This is probably not the first time that this has happened,” McDowell said. “It’s just the first time that we’ve been paying enough attention to notice.”
What we now think is the Chang’e 5-T1 rocket booster is set to hit the moon on March 4 at around 7:30 in the morning. If you’re hoping to see it, you’re out of luck: It will hit the far side of the moon, which means it won’t be visible to us now or ever. The moon’s rotation is locked with the Earth’s, so we always see the same side of it. But it is possible that some of the objects in lunar orbit will get an image of the crater it leaves. NASA told Recode that its lunar orbiter won’t be in a position to see the impact, but it will look for the crater. It could take “weeks or months” to find it.
McDowell said he hopes this incident will make the general public aware of the gaps in our knowledge when it comes to man-made objects floating around deep space, wherever they are. He’d like to see an international database of all launches with their trajectories, as well as funding for at least one person to track them. That’s going to be especially important in the coming decades as the amount of lunar traffic increases and the number of countries and private companies creating it do, too. We have a chance now to prepare for later.
“It’s getting confusing out there. Let’s get organized,” McDowell said.
As for the location of that SpaceX rocket that was initially blamed for the upcoming moon crash? We can only guess at it. Perhaps we’ll see it again someday, but no one seems to know for sure.
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