A team of scientists confirmed that the strange near-Earth object (NEO, for its acronym in English) 2020 SO It is a Centaur booster rocket from the 1960s. The NEO had been discovered in September by astronomers looking for nearby asteroids and ended up sparking the interest of the entire scientific community due to its unusual size and orbit.
To confirm the artificial origin of the object, the scientists used data collected at NASA’s Infrared Telescope Facility (IRTF) and orbit analysis from the Center for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory. from NASA.
A detailed analysis of the 2020 SO orbit revealed that it had come close to Earth several times over the decades, with a focus in 1966 bringing it close enough to suggest that it may have originated from our planet.
Comparing this data with the history of previous NASA missions, Paul Chodas, director of CNEOS, concluded that 2020 SO could be the Centaur upper stage booster rocket from NASA’s failed 1966 Surveyor 2 mission to the Moon.
With this data in mind, a team led by Vishnu Reddy, associate professor and planetary scientist at the University of Arizona’s Lunar and Planetary Laboratory, conducted follow-up spectroscopy observations of 2020 SO using NASA’s IRTF in Maunakea, Hawaii.
The work behind detection
“Due to the extreme weakness of this object following the CNEOS prediction, it was a difficult object to characterize. We obtained color observations with the Large Binocular Telescope, or LBT, which suggested that 2020 SO was not an asteroid “Reddy said in a statement.
Through a series of follow-up observations, Reddy and his team analyzed the composition of 2020 SO using NASA’s IRTF and compared the 2020 SO spectrum data with that of 301 stainless steel, the material from which rocket propellants were made. Centaur in the 1960s.
While not a perfect match at first, the team persisted in realizing that the discrepancy in the spectrum data could be the result of testing new steel in a laboratory against steel that would have been exposed to harsh space weather conditions. for 54 years. This prompted the group to conduct additional research.
“We knew that if we wanted to compare apples to apples, we would have to try to get spectral data from another Centaurus rocket booster that had been in Earth orbit for many years and then see if it would better match the 2020 SO spectrum,” Reddy said.
“Because of the extreme speed at which Earth-orbiting Centaur thrusters travel through the sky, we knew that it would be extremely difficult to fix the IRTF long enough to get a robust and reliable data set,” he added.
The key to a second rocket
Despite these difficulties, in the early morning of December 1, Reddy and his team accomplished what they thought would be impossible.
Scientists observed another Centaur D booster rocket from the 1971 launch of a communications satellite that was in Geostationary Transfer Orbit, long enough to get a good spectrum.
The team then compared this new data to SO 2020 and found the spectra to be consistent with each other, thus coming to the definitive conclusion that SO 2020 is also a Centaur rocket booster.
“This conclusion was the result of a tremendous team effort. We were finally able to solve this mystery thanks to the great work of Pan-STARRS, Paul Chodas and the team from CNEOS, LBT, IRTF and observations around the world, ”said Reddy.
2020 SO made its closest approach to Earth on December 1, 2020 and will remain within Earth’s gravitational domain sphere, a region in space called the “Hill Sphere” that extends approximately 1.5 million kilometers from our planet, until it escapes back into a new orbit around the Sun in March 2021.