Back on November 13, we brought you a story that researchers using the Pan-STARRS1 survey telescope had discovered a new object known as 2020 SO and that it might be a long lost Centaur rocket booster from the 1960s. Well, scientists have now confirmed that this object is indeed that rocket booster.

A team from the Lunar and Planetary Laboratory at the University of Arizona used NASA’s Infrared Telescope Facility (IRTF) to get spectrum data of 2020 SO to compare to 301 stainless steel, which is what the Centaurs were made with. At first, the data were not a perfect match, and the discrepancy was thought to be due to the effects of space weather on the booster. So the team set out to observe another Centaur rocket booster known to be in orbit around Earth.

However, that’s not as easy as it first sounds. As team lead Vishnu Reddy said: Because of the extreme speed at which Earth-orbiting Centaur boosters travel across the sky, we knew it would be extremely difficult to lock on with the IRTF long enough to get a solid and reliable data set.

The team pulled off what seemed to be impossible on December 1, gathering spectrum data on a 1971 Centaur booster. A new comparison to the 2020 SO spectra was performed, and they were a definitive match.

Now, 2020 SO will not stay in orbit around Earth for very long. It’s expected to escape back out into a new solar orbit next March. Still, as Reddy pointed out: This conclusion was the result of a tremendous team effort. We were finally able to solve this mystery because of the great work of Pan-STARRS, Paul Chodas and the team at [Center for NEO Studies] CNEOS, [Large Binocular Telescope] LBT, IRTF, and the observations around the world.

So congrats to all involved. It’s nice to see something work this year.

More Information

NASA JPL press release