They discover a star that can also be visited by the space probe Lucy

Even before its launch, NASA’s Lucy spacecraft already had a mission ahead of it that should make it the spacecraft with the most asteroids visited of all existing spacecraft. Now, when it is still flying towards the first of its objectives, and thanks to the surprising result of a long observation campaign, the mission can add one more asteroid to the list of those that will be visited by the spacecraft.

Trojan asteroids, named after characters in Greek mythology, revolve around the Sun in two clouds. One of them precedes Jupiter in its orbital path. The other follows the planet behind. Lucy will be the first spacecraft to visit such asteroids.

On March 27, the Lucy mission science team discovered the first signs that the smallest of the Trojan asteroids to visit during the mission, Polymele, has a satellite of its own. That day, Polymele was expected to pass in front of a star, from Earth’s visual perspective, allowing the team to watch the star flicker as the asteroid briefly obscured it. Distributing 26 teams of professional and amateur astronomers along the path in which the occultation would be visible, the Lucy mission team planned to measure Polymele’s location, size, and shape with unprecedented precision as it loomed over the moon. star behind him. These stealth campaigns have been hugely successful in the past, providing valuable information to their corresponding mission about their observation targets, but today would have a special bonus.

After careful analysis of the data collected from the observations, the team led by Marc Buie, a scientist at the Southwest Research Institute in the United States and a member of the Lucy mission science team, realized that two of the observations had detected a object about 200 kilometers away from Polymele. It had to be a satellite.

Using data from the occultation, the team determined that this satellite is about 5 kilometers across and confirmed that it orbits Polymele, which itself is about 27 kilometers across. Following planetary naming conventions, the satellite will not receive an official name until the team can determine its orbit. As the satellite is too close to Polymele to be seen clearly by ground-based or Earth-orbiting telescopes (without the help of a star directly behind it at some point) its christening will have to wait until the team gets lucky with an occultation. suitable or until Lucy approaches the asteroid in 2027. At the time of the observations that have allowed the satellite to be discovered, Polymele was at a distance of 770 million kilometers from Earth.

Artist’s impression of the asteroid Polymele, which has recently been found to have a satellite. (Illustration: NASA’s Goddard Space Flight Center)

Asteroids contain vital clues to deciphering the history of the solar system, and perhaps even the origins of life. Solving these two mysteries is one of NASA’s top priorities. The Lucy mission team originally planned for the spacecraft to visit one main-belt asteroid and six Trojan asteroids. In January 2021, the team discovered, using the Hubble Space Telescope, that one of the Trojan asteroids, Eurybates, has a small satellite. Now, with this new satellite, Lucy is on her way to visit nine asteroids in this incredible 12-year journey. (Font: NCYT by Amazings)