Mini moon to orbit Earth may in fact be 1960s space junk
An asteroid likely to get caught in Earth’s orbit and become a “mini moon” for several months may in fact not be an asteroid at all.
Dubbed 2020 SO, the object is on track to be pulled into Earth’s orbit in the coming weeks and circle the planet until it returns to its own track.
But instead of being space rock, experts think it is actually part of a rocket from a failed moon-landing mission in 1966.
“I’m pretty jazzed about this,” Paul Chodas, director of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory, told The Associated Press. “It’s been a hobby of mine to find one of these and draw such a link, and I’ve been doing it for decades now.”
Mini moons – objects that temporarily orbit Earth – are rare. While more have likely occurred over history, only two have been confirmed: one from 2006 to 2007 and another discovered earlier this year that was in orbit from 2018 to 2020, according to space and astronomy news outlet Universe Today.
While those mini moons were space rocks, 2020 SO has a few characteristics that make scientists skeptical.
Its orbit is nearly a circle, similar to Earth’s, and is not tilted, on the same plane as Earth. The object is also moving much slower than scientists would expect a similar asteroid to move.
“The velocity seems to be a big one,” space archaeologist Alice Gorman of Flinders University in Australia told science news outlet ScienceAlert. “What I’m seeing is that it’s just moving too slowly, which reflects its initial velocity. That’s essentially a big giveaway.”
The object was discovered by a telescope in Hawaii last month, and its dimensions appear to match that of the upper rocket stage from NASA’s Surveyor 2 lander.
Based on its brightness, 2020 SO is roughly 26 feet long. The Centaur rocket stage from the Surveyor 2 mission is less than 32 feet long and 10 feet in diameter.
The Centaur launched the lander to the moon during the mission and was discarded as space junk. But as the lander approached the moon, a thruster failed and sent the spacecraft spinning, and it ultimately crashed into the moon.
Gorman told ScienceAlert that discarded rocket parts can very easily become lost space junk.
“You have to keep tracking these things, or you can just sort of lose sight of them really easily. And if they do something a little bit unpredictable, and you look the wrong way, then you don’t know where it’s gone. It is quite astonishing, the number of things that have gone missing,” she said.
Carrie Nugent, an asteroid hunter at Olin College of Engineering in Needham, Massachusetts, told the AP that the conclusion that the object is space junk is “a good one.”
It is possible the object is a space rock, Chodas said. Scientists should be able to say with more certainty once it gets closer to Earth and they can track how it moves.
Said Chodas: “It’s the first time, in my view, that all the pieces fit together with an actual known launch.”