More minimoons to be discovered – Queen’s academic

Many more minimoons will be discovered in the next decade, a Queen’s University Belfast-led team of academics has said.

It comes after detail of the finding of the second minimoon – a free-floating silicate boulder named 2020 CD3 – was published in the Astronomical Journal.

Minimoons are small asteroids temporarily captured in Earth’s orbit before they are flung back out into space.

Grigori Fedorets, from the Astrophysics Research Centre at Queen’s – who led the multi-telescope observational campaign, described the sighting of the minimoon on February 15 as a “rare treat for astronomers”.

A global effort led by the astronomer from Queen’s was launched to compare it to findings recorded on the only other minimoon to confirm its status.

It is thought that 2020 CD3 could have entered the Earth’s orbit several years ago, but it was only visible by powerful telescopes on its way out of the Earth-Moon system, which it left on March 7.

“The discovery in February was significant as the only other minimoon astronomers have documented was recorded back in 2006, spending around a year on an orbit around the Earth,” said Mr Fedorets.

“Asteroid 2020 CD3 was a companion to the Earth for a longer time than the previous minimoon and we were able to calculate its orbit and study it in enough depth to derive its physical properties, and rotational period, proving that it was a natural and not an artificial body such as a dead satellite.

“Several powerful telescopes from around the world, including those in Hawaii and La Palma as well as the one Arizona were used for the study.

“Through observations our group confirmed that it is a silicate shard of a larger body. We also calculated that it was about 13,000 km from the Earth at its closest approach and somewhere between 1m and 1.5m meters in diameter – about the size of a small car.”

The research study, which involved 23 researchers from 14 academic institutions in seven countries, indicates more minimoons will be discovered.

“Updated calculations from our latest research estimate that we will be able to find several minimoons in the next decade. Projects like the upcoming Vera C. Rubin Observatory’s Legacy Survey of Space and Time, which will use the world’s largest digital camera will help astronomers to record them and learn more about the solar system,” Mr Fedorets said.

He also speculated that a space travel expedition to a minimoon is possible within the next decade.

“Perhaps the most exciting thing about minimoons is that they come very close to the Earth and spend a significant amount of time in its vicinity,” he said.

“That would make them outstanding targets for space missions.

“That could give us amazing insights into these one to 10 metre objects which we know so little about because up until now they have been so rare.

“This could help us learn about how asteroids and meteorites link, which is one of the fundamental questions in planetology.”