Over the past few months, the nature of a mysterious object of reduced size has raised many questions. It must be said that his trajectory is very surprising. According to the researchers, it is not a small asteroid or a mini-moon, but rather space debris.
In September 2020, astronomers discovered the small body 2020 SO. However, its nature was difficult to determine, keeping the experts in suspense for several weeks. Its trajectory is indeed surprising:the object has an orbit very similar to that of the Earth. In addition, its movement indicated that it was to become a satellite of our planet for a few months (see below).
In a press release published on December 2, 2020, the NASA has finally confirmed the nature of the 2020 SO object. It is the thruster of the upper stage of the Centaur launcher of the Surveyor 2 mission. Launched on September 20, 1966 towards the Moon, this mission proved to be a failure. The upper stage of the rocket measuring 12 m long by 3 m wide ended up in orbit around the sun.
In order to determine the nature of 2020 SO, several researchers conducted the investigation. One example is Marco Michelli, astronomer at the European Space Agency's (ESA) Near-Earth Object Coordination Center. The person concerned obtained measurements of the position of the object. However, its solar radiation pressure signature was quite strong. This has therefore made it possible to understand that 2020 SO is too light to be the result of a natural formation.
With his team, Vishnu Reddy, professor and planetary scientist at the Lunar and Planetary Laboratory of the University of Arizona (USA), conducted spectroscopic observations from 2020 SO using the Infrared Telescope Facility (IRTF). This is NASA's infrared telescope on Mauna Kea (Hawaii). In addition, other observations made by the Large Binocular Telescope (LBT) located in Arizona made it possible to affirm that 2020 SO was not an asteroid.
Vishnu Reddy and his team analyzed the composition of 2020 SO and compared its spectrum to that of 301 stainless steel, the material of the Centaur rocket boosters of the 1960s. If the two did not match perfectly, this difference can be explained. Indeed, the reference spectrum corresponds to fresh steel, while the steel of 2020 SO had suffered the harsh conditions of space for 54 years!
Experts then compared the spectrum of a Centaur D rocket booster launched in 1971 with 2020 SO. The two matched, so the researchers concluded that the object was also a Centaur rocket booster. It passed closest to our planet on December 1, 2020, at a distance of 50,000 km . It will remain in Earth's Hill sphere before heading back toward the sun in May 2021.
