Astronomers have discovered an object is on track to enter the Earth’s orbit in the next few weeks, becoming our newest mini-moon. But, they are beginning to suspect the object might not be an asteroid floating in space, but instead, manmade space junk from the 1960s.

Sometimes, asteroids flying by the Earth get trapped by the planet’s gravitational pull and orbit us for a while before floating away elsewhere. And, reportedly, even though various mini-moons have been detected in the past, only two, both asteroids, have been confirmed: 2006 RH120, which orbited Earth between 2006 and 2007; and 2020 CD3, which arrived in 2018, and departed earlier this year. But, until now, scientists have rarely had the opportunity to watch the process of the Earth acquiring a mini-moon in action.

Named 2020 SO, the new mini-moon is expected to start orbiting the Earth sometime in October or November of this year and pop out of orbit in May 2021. Reportedly, scientists had first spotted this object from a Hawaiian observatory in August, but as they continued studying it, they became more and more convinced that it may not be a new asteroid at all.

“I suspect this newly discovered object 2020 SO to be an old rocket booster because it is following an orbit about the Sun that is extremely similar to Earth’s, nearly circular, in the same plane, and only slightly farther away [from] the Sun at its farthest point… That’s precisely the kind of orbit that a rocket stage separated from a lunar mission would follow… It’s unlikely that an asteroid could have evolved into an orbit like this, but not impossible,” Paul Chodas, PhD, the director of NASA’s Center for Near Earth Object Studies, told CNN.

So, scientists suspect the soon-to-be mini-moon is space junk from the Cold War-era space race, which witnessed a series of “competitive technology demonstrations” between the US and the Soviet Union as both tried to establish superiority in space exploration.

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But not everyone is convinced that the soon-to-be mini-moon is space junk. While some astronomers believe it could be a discarded part of a rocket that launched Surveyor 2 to study the moon in September 1966, some insist that no rocket launches made within the estimated time period match 2020 SO’s behavior. However, scientists are hopeful that very soon, as the object nears the Earth, the debate will be laid to rest, and we’ll find out what the object really is by studying the effect of sunlight pressure on it.

“… If it really is a rocket body, it will be much less dense than an asteroid and the slight pressure due to sunlight will produce enough change in its motion that we should be able to detect it in the tracking data,” Chodas noted.

The confusion around the new mini-moon has only brought concerns regarding space junk to the forefront yet again. According to a 1978 theory proposed by Donald Kessler, a NASA scientist, too much trash in space could initiate a chain reaction causing more and more objects to collide, creating newer space junk and a greater density of trash, to the point where Earth’s orbit itself becomes unusablefor satellites — endangering everything from GPS, to military and scientific research, to even television. To avoid the accumulation of junk in space, researchers are presently exploring options like giant magnets and nets to bring down the debris, sending “space whips” to knock the debris out of orbit, and using the Earth’s atmosphere to burn up the debris.

2020 SO will come closest to the Earth, about 50,000 kilometers away, in December. Scientists are hopeful that if it indeed turns out to be a rocket, they’ll also be able to study it when it’s closest, to learn what happened to it during the last half-century in space — giving us insights that could help our future space exploration initiatives.