Asteroid Belt Could Be A ‘Treasure’ Of Planetary Building Blocks

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The asteroid belt may have started empty, later becoming a “cosmic refugee camp” taking the remnants of planetary formation from across the solar system, according to a new study.

The main asteroid belt, located between the orbits of Mars and Jupiter, represents 0.05% of the mass of the Earth. The asteroids there can vary greatly in mass, with the four largest – Ceres, Vesta, Pallas and Hygiea – holding more than half the mass of the belt.

To explain the dramatic range of sizes in the asteroid belt, previous models suggested that the primordial asteroid belt originally had a mass at least equal to that of Earth and that its members had less mass disparity. . The planets’ gravitational pull then helped shrink this primordial belt, depleting asteroids of some sizes more than others. [The Asteroid Belt Explained (Infographic)]

However, these earlier models of asteroid formation raised a question: how the belt was able to lose more than 99.9% of its mass without losing it entirely, the study’s lead author said. Sean Raymond, astronomer at the University of Bordeaux in France.

“Our approach is the opposite. We asked the question, ‘Could the asteroid belt have been born empty? “” Raymond told Space.com. “The answer is yes, effortlessly.”

Birth of the asteroid belt

Most asteroids orbit the sun in a wide belt located between the orbits of Mars and Jupiter: the asteroid belt. Get the facts about the asteroid belt in this SPACE.com infographic. (Image credit: Karl Tate, SPACE.com contributor)

Scientists developed computer models of an empty primordial asteroid belt to see if the remnants of the planetary formation could explain the belt’s current composition. The inner belt is dominated by dry S-type, or siliceous, asteroids, which appear to be made of silicate materials and nickel iron and make up about 17 percent of known asteroids. The outer belt is dominated by water-rich C-type, or carbonaceous, asteroids, which consist of clay and stony silicate rocks and make up more than 75 percent of known asteroids.

Researchers have found that an empty primordial asteroid belt could explain the mass and makeup of the current members of the asteroid belt. This model suggests that this area between Mars and Jupiter is a repository of planetary remnants, “a refugee camp housing objects that have been evicted from their homes and left to brave interplanetary space, eventually settling into stable orbits in the asteroid belt, ”Raymond said. Espace.com. [The Strangest Asteroids in the Solar System]

In this new model, the inner belt consists largely of rocky remains from the formation of the terrestrial planets – Earth, Mars, Venus and Mercury. In contrast, the outer belt is made up of vestiges of the formation of giant gas planets, such as Jupiter and Saturn.

“In terms of composition, Jupiter and Saturn grew up in a much cooler region than where the rocky planets developed,” Raymond said. “Being cooler, their cores could incorporate ice and other volatile substances. C types contain about 10% water, while S types are much drier, starting in the much warmer area of ​​the sea. Earth.”

Relics of the solar system

These findings suggest that the asteroid belt “is a treasure – it must contain relics of the building blocks of all the planets,” Raymond said. “There must be pieces of earthly building blocks in the asteroid belt, as well as remnants of the construction of the nuclei of the giant planets.”

Future research may further test how well different models of asteroid belt formation correspond to reality. Raymond hopes the team’s new concept “will help keep people’s minds open to stories of potentially radically different origins for the solar system, as well as extra-solar planets.”

Raymond and his colleague Andre Izidoro from the University of Bordeaux detailed their findings online on September 13 in the journal Science Advances.

Follow Charles Q. Choi on Twitter @cqchoi. Follow us @Spacedotcom, Facebook and Google+.



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