Space telescope detects 352 new double asteroids
The companions of asteroids are difficult to find. Only a tiny telltale wobble draws attention to them. Now the number of known asteroid moons has almost doubled.
With the help of the European space probe Gaia, experts have discovered more than 350 new possible moons around asteroids that were not previously known to have a companion. "Such double asteroids are difficult to find because they are usually small and far away from us," said the European Space Agency ESA, quoting the lead author of the study, Luana Liberato from the Observatoire de la Côte d'Azur, in a press release. It is assumed that almost every sixth asteroid has a companion. However, of the approximately one million known asteroids, only 500 such double asteroids have been discovered so far. This number has therefore almost doubled. The research group reports on this in the scientific journal "Astronomy & Astrophysics".
Asteroids provide unique insights into the formation and development of the solar system. Together with comets, they are categorised as small bodies and date back to the time of planet formation around 4.5 billion years ago. Most of them orbit between Mars and Jupiter in the asteroid belt. Double asteroids are particularly exciting because they can be used to study how different bodies form, collide and interact in space.
The ESA's Gaia mission aims to record the positions, movements, distances and brightness of almost two billion stars. During Gaia's observations, however, foreground asteroids also repeatedly come into the field of vision of the instruments on board. The Gaia observations of such small bodies can therefore be described as scientific by-catch of the mission. The current data set of more than 150,000 recorded asteroid orbits enabled the researchers to search for a wobble typical of double asteroids, which is caused by the gravitational influence of an orbiting companion. Gaia also collected data on the chemistry of asteroids and compiled the largest collection of asteroid reflectance spectra to date.
Probably the most famous double asteroid is the Didymos-Dimorphos system, which received a powerful visit from the DART space probe in September 2022. At the time, ESA and the American space agency NASA were jointly testing whether an asteroid could be deflected from its trajectory. To this end, DART hit the asteroid moon Dimorphos, shortening its orbit around the asteroid Didymos by around 32 minutes. It was the first attempt in the history of space exploration to change the trajectory of a celestial body. Among other things, the precise measurement data from the Gaia telescope helped the astronomers to plan the scenario and observe the subsequent changes.
"The Gaia telescope has proven to be an excellent asteroid explorer, working hard to unravel the mysteries of the cosmos both inside and outside the solar system," said Timo Prusti, Gaia project scientist at ESA. "This result shows that every release of Gaia data moves us forward." The next large dataset is expected to contain even more details on additional asteroid orbits and is expected in mid-2026.
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