A manmade object has traveled through space for years before being re-captured by Earth's gravity and is soon to be flung again into the far reaches of space — and it's not Tesla's Roadster-riding Starman.
The space object in question, known until yesterday as '2020 SO', has been confirmed by NASA to be a 1960’s-Era Centaur rocket booster that has made several close orbits to Earth since it launched over 50 years ago.
Aliens or the Centaur upper stage rocket?
'2020 SO' was first discovered in September by astronomers searching for near-Earth asteroids using the Pan-STARRS1 survey telescope on Maui.
The object garnered interest within the scientific community due to its size and unusual orbit — inevitable alien memes also surfaced online after the observation of '2020 SO' was made public.
Further analysis of 2020 SO's orbit revealed the object had come close to Earth several times over the decades. One approach in 1966, in particular, brought it close enough to Earth to suggest it may, in fact, have originated on our planet.
After comparing the data with the history of previous NASA missions, Paul Chodas, CNEOS director, concluded that 2020 SO may well be the Centaur upper stage rocket booster from NASA’s ill-fated 1966 Surveyor 2 mission to the Moon.
Now, follow-up spectroscopy observations of 2020 SO, using NASA’s IRTF on Maunakea, Hawai’i, have confirmed that the space object is in fact the 1966 Centaur upper stage rocket booster.
"Due to extreme faintness of this object following CNEOS prediction it was a challenging object to characterize," explained Vishnu Reddy, NASA's team lead for the observations.
"We got color observations with the Large Binocular Telescope or LBT that suggested 2020 SO was not an asteroid," he continued.
To begin with, the team's spectroscopy observations were not a perfect match with the steel used for NASA's rocket booster in 1966.
However, Reddy and his team soon realized that the discrepancy in spectrum data might be caused by the fact that they were comparing 2020 SO to fresh steel in a lab rather than steel that had been exposed to the harsh space condition for 54 years.
"We knew that if we wanted to compare apples to apples, we’d need to try to get spectral data from another Centaur rocket booster that had been in Earth orbit for many years to then see if it better matched 2020 SO’s spectrum," said Reddy. "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."
2020 SO's future trajectory
Impressively, Reddy and his team were able to observe another Centaur D rocket booster from 1971 that was in Geostationary Transfer Orbit long enough to get a good spectrum reading.
With the new data, the team was able to compare it against 2020 SO and find the spectra to be consistent with one another. The conclusion, therefore, is that 2020 SO is also a Centaur rocket booster.
NASA says that 2020 SO made its closest approach to Earth on December 1, 2020, and will remain within Earth's sphere of gravitational dominance — which extends approximately 930,000 miles (1.5 million kilometers) into space — until it escapes back into a new orbit around the Sun in March 2021.
Astronomers will continue to take observations of 2020 SO to collect data that will help future observers more easily distinguish between the growing number of manmade objects in space and asteroids.