A strange near-Earth object (NEO) recently discovered orbiting close to our planet turns out to be the propellant of a rocket from the 1960s, NASA announced. Object 2020 SO was originally thought to be an asteroid, but it was notable for having an unusual orbit that brought it closer to our planet. Now closer examination has confirmed that 2020 SO is a visitor from the past, part of the 1966 Surveyor 2 mission to the moon.
Surveyor 2 was intended to be an unmanned lunar lander that would photograph the moon’s surface prior to the manned Apollo 11 mission that landed in 1969. Surveyor 2, however, was not so lucky, and during its trip to the moon one of its thrusters failed, sending it tumbling and causing operators on the ground to lose contact with the craft. However, a small part remains in the shape of the Centaur upper stage booster rocket that was recently captured by Earth’s gravity and which will orbit our planet for a few more months.
To confirm that the detected object was indeed a booster, a NASA team observed it using the Infrared Telescope Facility (IRTF) in Maunakea, Hawaii, but this was difficult. “Due to the extreme weakness of this object following the CNEOS prediction, it was a difficult object to characterize,” team leader Vishnu Reddy said in a statement. “We obtained color observations with the Large Binocular Telescope, or LBT, which suggested that 2020 SO was not an asteroid.”
The team made more follow-up observations and was able to confirm that the composition of the object matched the 301 stainless steel used in Centaur rocket boosters, although the readings were slightly altered by the 54 years the material had spent in space.
“We knew that if we wanted to compare apples to apples, we would have to try to get spectral data from another Centaur rocket booster that had been in Earth orbit for many years and then see if it would better match the 2020 SO spectrum,” he said. Reddy. “Due to 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 obtain a robust and reliable data set.”
Luckily, there was another similar Centaur booster rocket from 1971 in orbit, and the team was able to observe this. By comparing the readings of the 1971 booster with the new object, they were able to confirm that the 2020 SO object was also a Centaurus booster. Mystery solved.