In the wee hours of Tuesday morning, an object in space zipped by Earth at a distance of about 27,000 miles. The object has been given the not-so-descriptive designation of "2020 SO," and while nobody knows with certainty what it is, NASA researchers have an intriguing guess. In short, they think it's the remnants of a failed mission to the moon in 1966, reports the New York Times. More specifically, it appears to be the upper-stage rocket booster from NASA's doomed Surveyor 2 mission, per NASA. The unmanned mission sent up a lander to take photos ahead of the Apollo flights, but the spacecraft crashed into the moon and was destroyed. Its rocket booster, however, already had disengaged and flew by the moon into space. Now, it appears, the booster has come home, at least temporarily.
"It was like a eureka moment when a quick check of launch dates for lunar missions showed a match with the Surveyor 2 mission," says Paul Chodas, manager of NASA's Center for Near Earth Object Studies, per CNET. He's referring to the nifty sleuthing that may have solved the puzzle. After astronomers in Maui spotted the object in September, Chodas ran its orbit in reverse and concluded that it likely originated from Earth in September 1966, when Surveyor 2 was launched. Analysis of Tuesday morning's flyby could confirm that it is indeed the mission's rocket booster. As for 2020 SO, it won't be with us long. The object will escape the Earth's orbit in March and return to an orbit around the sun—at least for a while. "In 2036, it's coming back," says Chodas. (China has just begun an ambitious moon mission of its own.)