The European Space Agency’s (ESA) Gaia mission, initially launched for star surveying, has made a remarkable leap in asteroid exploration. Gaia has identified potential moons orbiting over 350 asteroids that were previously thought to have no companions, significantly expanding our knowledge of binary asteroid systems.
Previously, Gaia confirmed moons around asteroids already known to have companions, using its precise astrometric data. This new discovery demonstrates Gaia’s capability for ‘blind’ searches, revealing entirely new binary asteroid candidates.
“Binary asteroids are challenging to detect due to their small size and great distance,” said Luana Liberato from Observatoire de la Côte d’Azur, France, and lead author of the study. ” This discovery suggests many more asteroid moons are yet to be found.”
If confirmed, these findings could nearly double the known number of asteroids with moons, adding 352 new binary candidates to the list. Binary asteroids offer valuable insights into the formation and evolution of our Solar System, helping scientists understand how celestial bodies interact and evolve in space.
Since its launch in 2013, Gaia has been instrumental in asteroid research. Its third data release pinpointed the positions and movements of over 150,000 asteroids, allowing scientists to detect the ‘wobble’ caused by orbiting companions. Gaia also provided the most comprehensive collection of asteroid reflectance spectra, revealing details about their color and composition.
The precision of Gaia’s data was enhanced by its Focused Product Release last year, and even more detailed asteroid orbits are expected in Gaia’s fourth data release, anticipated by mid-2026.
. “This discovery highlights the continuous improvement in data quality and the exciting new science Gaia enables.”
ESA’s Hera mission, launching later this year, will further explore binary asteroids. Hera will follow NASA’s DART mission, which tested asteroid deflection by colliding with the moonlet Dimorphos in 2022, and will conduct a post-impact survey of Dimorphos, marking the first probe to visit a binary asteroid system.
Gaia’s contributions have also enhanced techniques like stellar occultation, where astronomers observe the shadow of an asteroid passing in front of distant stars, showcasing the mission’s significant role in Solar System exploration.
