Science

Colors, shapes and brightness levels of asteroids revealed in new Gaia satellite data

The Milky Way mapping satellite Gaia has released its third data catalog, which includes 10 times more asteroid information than its second data catalog, indicating an increase in “close collisions” between space rocks tracked by Gaia.

These close encounters can be used to estimate a number of characteristics of asteroids, especially their masses.

The third Gaia catalog also improves on its predecessors by including spectral observations of asteroids for the first time. The release contains spectra or measurements of the color and brightness of asteroids at different wavelengths from approximately 60,000 asteroids.

On the subject: How the bluest asteroid in the solar system got its color

These spectra can be used to determine the composition of asteroids, which are unspoiled material left over from the formation of the planets about 4.6 billion years ago.

Astronomers currently have spectra of only a few thousand asteroids, and scientists at the University of Helsinki in Finland predict that Gaia could increase that number by a factor of ten. This means the Gaia data could help astronomers better understand the solar system and its evolution.

The Gaia data also shows that while the flying saucer-shaped satellite has made a splash by delivering data on distant stars and exoplanets in the Milky Way, Gaia is more than capable of influencing science much closer to home.

The Gaia mission differs from the Hubble Space Telescope and the James Webb Space Telescope in that instead of choosing an object or group of objects and studying them intensively, Gaia maps the entire sky by making repeated observations.

This method allows Gaia to target billions of stars and observe how their positions change over time. Because these stars are so far away, the movements the spacecraft sees are tiny. But when Gaia notices a faint light source moving into the spacecraft’s field of view so fast that the object is only visible in one image before disappearing, it indicates that the body is much closer to Earth.

Checking these bodies against databases of known Solar System bodies allows researchers to determine if objects are previously discovered asteroids, and this cross-validation method often leads to new discoveries.

Gaia’s high-precision stellar position monitoring is a key tool in tracking asteroids.

Asteroid Lutetia, one of the asteroids that Gaia astrometry used to study, as seen by the Rosetta mission.

Asteroid Lutetia, one of the asteroids that Gaia astrometry used to study, as seen by the Rosetta mission. (Image credit: ESA 2010 MPS for OSIRIS MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA team)

“When we observe an asteroid, we look at its motion relative to the background stars to determine its trajectory and predict where it will be in the future,” said Marco Micheli, scientist at the European Space Agency’s (ESA) Near-Earth Object Coordination Council . Center, the report said. (will open in a new tab). “This means that the more precisely we know the position of the stars, the more reliably we can determine the orbit of an asteroid passing in front of them.”

Gaia uses a method called astrometry to calculate the mass of asteroids. This method, which dates back to 190 BC when the Greek astronomer Hipparchus used it to create star catalogs, uses precise movements of celestial bodies to create detailed databases of such objects, including asteroids.

The astrometry conducted by Gaia differs from the usual calculation of an asteroid’s orbit, which assumes that the object has a point shape with no defined shape, therefore does not take into account the size, rotation, light scattering properties of the surface, and the actual real shape. asteroid.

Because of Gaia’s impressive accuracy, the astrometry it draws depends on the angle at which the asteroid’s center of mass is offset from the center of the sunlit region of the body. This offset was determined for the asteroid (21) Lutetia, which was extensively studied by ESA’s Rosetta mission in 2010.

Using Rosetta data and physical information collected by ground-based telescopes allowed Gaia to remove systematic errors and determine the rotation period, rotation pole orientation, and a detailed shape model of Lutetia. By doing this for Lutetia and other asteroids, Gaia astrometry can help gather detailed physical information that researchers can then use to make more detailed observations and study the origin and evolution of the solar system.

“There are so many revolutionary achievements that it is difficult to single out one most significant achievement,” University of Helsinki professor Karri Muinonen said in a statement. “Based on Gaia DR3 [data release 3]Finnish researchers will change the way we think about asteroids in our solar system.”

A complete overview of the Gaia data is available from ESA. (will open in a new tab).

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