These 352 asteroids likely have cute little moons
Identifying asteroids that may have moons could help researchers understand unique aspects of our solar system.
An illustration of a binary asteroid system.
Mark Garlick/Science Photo Library/Alamy Stock Photos
An ultra-high-precision satellite tasked with mapping more than a billion stars across the galaxy has discovered something interesting closer to home: 352 asteroids in our solar system that likely have their own moons. Known as “binary asteroids,” these systems are difficult to pinpoint due to their distance from Earth and their relatively small size.
Scientists zeroed in on these systems by examining data on the objects’ movements from the European Space Agency’s Gaia spacecraft, which is drifting about 930,000 miles (1.5 million kilometers) from Earth. This is the first set of potential binary asteroids identified using only the objects’ positions and movements, says Luana Liberato, an astrophysicist at the Canadian Space Agency. Cote d’Azur Observatory He lives in France and is lead author of the study published today. Astronomy and Astrophysics.
The Gaia spacecraft consists of two optical telescopes that reflect light onto special detectors, allowing it to record the precise movements of the many celestial objects that orbit our solar system at breakneck speed. For the study, the team analyzed measurements from the Gaia mission’s third data release and searched through more than 150,000 asteroids identified by the spacecraft for signs of “wobble,” a change in an object’s expected position that is thought to be caused by the gravitational forces of another object orbiting it.
Supporting science journalism
If you enjoyed this article, please support our award-winning journalism. Subscribe. By purchasing a subscription, you help ensure a future of influential stories about the discoveries and ideas shaping the world today.
Orbits of 156,823 asteroids identified as part of Gaia Data Release 3. The broad blue and yellow circles in the frame indicate the orbits of planets, while the countless colorful swirls are asteroids. The central region is all within the orbit of Jupiter (Blue Circle).
“Most of the binary asteroids we know about have been discovered from the ground,” says Jay McMahon, an aerospace engineer at the University of Colorado Boulder who was not involved in the study. “We’re lucky that they get close enough to Earth.”
Gaia “is a really big, sensitive telescope,” McMahon continues, “and it’s been able to discover and characterize much more than we’ve ever done on the ground.”
Asteroids are rocks left over from the early solar system, and while further analysis is needed to determine whether these candidate systems are in fact what they seem, the newly discovered binary systems can help us learn more about the structure and movement of asteroids, which could provide unique insights into the formation of our solar system.
“It’s very difficult to measure the mass of an asteroid,” said Shantanu Naidu, a radar astronomer at NASA’s Jet Propulsion Laboratory who studies binary asteroid systems and was not involved in the new study. “In binary systems, you can measure the period that the moon orbits, and in that case you can directly measure the mass of the system.”
Knowing this mass allows researchers to calculate the asteroid’s volume and density, and to work out its composition and porosity. “Once we know these properties, we can start to piece together the pieces and get a complete picture of how the asteroid evolved,” Naidu says.
ESA and NASA have also conducted other missions aimed at improving our understanding of binary asteroid systems. For example, the recent Double Asteroid Reorientation Test (DART) mission slammed a spacecraft into an asteroid moon to investigate potential ways to protect against planet-threatening asteroids. ESA’s Hera mission, due to launch in October, will assess the post-impact situation of the DART mission.
Knowledge of the composition and evolution of binary asteroids could reveal even more far-reaching details. “Asteroids are the building blocks of planets and play a role in the formation history of our solar system,” Liberato says. “Studying binary asteroids can help us better understand the physical and chemical processes that take place during planetary formation and evolution, including collision dynamics, gravitational interactions, and material exchange.”
