Earth’s Homemade Rocket Turned ‘Mini-Moon’ Is Back To Say Goodbye

You know Earth’s main moon. It’s hard to miss right now. But every now and then, our planet’s gravity temporarily captures smaller celestial objects like asteroids and they become little “mini-moons” for a period.

In February 2020, for just the second time, astronomers discovered a captured asteroid orbiting Earth, a mini-moon called 2020 CD3. Then, just a few months later, in September, it looked as though the third such mini-moon had been spotted.

The object was first presumed to be an asteroid and was designated 2020 SO. It approached earth and was officially captured by our gravity in November, beginning the first of two orbits around us.

It made a very close approach on December 1, 2020, coming almost as close to the surface of Earth as the ring where many of our larger telecommunications satellites orbit. This allowed professional sky watchers to get a closer look at the object and determine that it was a relatively new denizen of space.

NASA was able to confirm that 2020 SO is actually the Centaur upper stage rocket booster from the doomed Surveyor 2 mission to the Moon. 

The 1966 mission was meant to make a soft landing on the lunar surface but a thruster failure led to a dramatic crash landing instead.

But the rocket booster survived and was lost from our view for over a half century.

That is until it passed too close last year and got swept up in our gravitational field. Now 2020 SO is set to make its second close approach next week. After that, it’s expected to break free again and head back into orbit around the sun.

This fly-by wont be as close as the one in December, but it will still be closer to our planet than our actual moon for a brief period.

Its moment of closest approach comes on Feb. 2. The Virtual Telescope Project and astrophysicist Gianluca Masi, based in Rome, will host an online viewing and farewell party for 2020 SO on Feb. 1, starting at 10 p.m. UTC (5 p.m. ET).