NASA firs reported 2020 SO as an asteroid in September 2020
In December, it came within 30,000 miles of Earth, allowing closer analysis
It was confirmed to be a Centaur booster rocket from 1966 s Surveyor 2 mission
2020 SO will make one last pass on February 1 and 2 before heading into space
There have been two other reported mini-moons, in 2006 and in February 2020