Gaia reveals moons around hundreds of asteroids

ESA’s Gaia mission, fabulous in its own right as a star surveyor, has recently spotted potential moons around more than 350 asteroids.

This extraordinary discovery is detailed in a new study led by Luana Liberato of Observatoire de la Côte d’Azur in France.

“Binary asteroids are difficult to find as they are mostly so small and far away from us,” says Liberato.

“Despite us expecting just under one-sixth of asteroids to have a companion, so far we have only found 500 of the million known asteroids to be in binary systems. But this discovery shows that there are many asteroid moons out there just waiting to be found.”

The intrigue of asteroids

Asteroids have always been intriguing – not just because they hurtle through space at unthinkable speeds – but also because these celestial bodies hold unique insights into the formation and evolution of the solar system.

Gaia has been an asteroid explorer since its launch in 2013. The spacecraft is known for its all-sky scanning capabilities, which have led to a number of remarkable asteroid discoveries.

What makes this recent discovery even more riveting is that it almost doubles our tally of known asteroids with moons – leaping from 500 to a whopping 852 potential binary asteroid candidates.

Gaia goes beyond simply locating asteroids; it has assembled the largest collection of asteroid “reflectance spectra” to date. These light curves play a vital role in uncovering an asteroid’s color and composition, providing valuable insights into their characteristics.

By analyzing this data, scientists can better understand the nature and evolution of these celestial bodies, enhancing our knowledge of the solar system and the processes that shape it.

Unique insights from binary asteroids

In Gaia’s third data release, scientists successfully pinpointed the positions and motions of more than 150,000 asteroids. They even zeroed in on asteroid orbits so accurately that it became possible to identify asteroids exhibiting a “wobble” – a characteristic sign of a nearby companion.

The discovery of potential moons around these asteroids could revolutionize our understanding of the dynamics within asteroid systems. 

Moons may provide clues about the history and formation of these celestial bodies, shedding light on the processes that have governed their development over billions of years. 

Additionally, studying these moon-asteroid pairs could enhance our knowledge of the gravitational interactions that influence their orbits and stability, potentially leading to more accurate models of solar system evolution.

“Binary asteroids have attracted the attention of the scientific community due to their interesting properties and the significant impact they have on our understanding of the solar system,” noted the study authors.

“Unlike single asteroids, binary systems offer unique insights into many fundamental processes, including the formation and evolution of planetary bodies, collision dynamics, and gravitational interactions.”

What lies ahead?

As we look to the future, the advancements brought about by Gaia’s findings pave the way for even more profound explorations. 

Upcoming missions, such as spacecraft targeting asteroids for direct observation, aim to gather even more data and samples. 

Enhanced technology and methodologies will allow scientists to delve deeper into the mysteries of asteroids, their compositions, and their potential for mining resources. 

The continued collaboration of observatories and space agencies worldwide will undoubtedly propel us toward more exciting discoveries that await among the stars.

Upcoming exploration of binary asteroids

With ESA’s forthcoming Hera mission, the exploration of binary asteroids is going to reach a new pinnacle. 

Hera will follow up on NASA’s DART mission, which had a rendezvous with Dimorphos, a moonlet orbiting the asteroid Didymos. The mission will also provide a post-impact survey of Dimorphos, marking another first for mankind – a probe rendezvous with a binary asteroid system.

“Gaia has proven to be an outstanding asteroid explorer, and is hard at work revealing the secrets of the cosmos both within and beyond the solar system,” says Timo Prusti, project scientist for Gaia at ESA. 

“This finding highlights how each Gaia data release is a major step up in data quality, and demonstrates the amazing new science made possible by the mission.”

The study is published in the journal Astronomy & Astrophysics.

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