NASA's Lucy team discovers moon around asteroid Polymele

The Lucy mission was going to break records by visiting more asteroids than any previous mission. After a long running observation campaign, the mission can add another asteroid to the list.

Lucy's science team discovered that Polymele has a satellite of its own. Polymele was expected to pass in front of a star, which would allow the team to observe the star blink out as the asteroid briefly blocked it. The Lucy team planned to measure the location, size, and shape of Polymle with unprecedented precision while it was outlined by the star behind it. This day would hold a special bonus because of the success of these campaigns in the past.

"We were thrilled that 14 teams reported observing the star blink out as it passed behind the asteroid, but as we analyzed the data, we saw that two of the observations were not like the others." Two observers spotted an object 200 km away from Polymele. It had to be a piece of technology.

The team used the data to estimate that the satellite is around 5 km in diameter and around 27 km in length. There was a distance between the two bodies. The team will not be given an official name for the satellite until they know its location.

As the satellite is too close to Polymele to be seen by Earth-based telescopes without the help of a fortuitously positioned star, that determination will have to wait until either the team gets lucky with future occultation attempts or until Lucy approaches the asteroid. The Polymele was 480 million miles from Earth. It's like trying to find a quarter on a sidewalk in Los Angeles, while trying to see it from a skyscraper.

The history of the solar system can be deciphered by studying asteroids, which hold important clues. The Lucy team had planned to visit one main belt asteroid and six Trojan asteroids, a previously unexplored population of asteroids that lead and follow Jupiter. The team used the Hubble Space Telescope to find a small satellite on Eurybates. Lucy is on her way to visit nine asteroids over the course of 12 years.

Lucy's slogan was 12 years, seven asteroids, one spaceship, said Tom Statler at NASA Headquarters in Washington. It's a good problem to have because we have to change the slogan for this mission.