A team of scientists from NASA have discovered the evidence of abundant water-bearing minerals on the surface of the near-Earth asteroid Bennu.
Bennu is the target of NASA's Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission, which began orbiting the asteroid on December 31.
"The scientists are interested in the composition of Bennu because similar objects may have seeded the Earth with water and organic materials," said the study's lead author Victoria Hamilton from the Southwest Research Institute.
"OSIRIS-REx data confirm previous ground-based observations pointing to aqueously altered, hydrated minerals on the surface of the asteroid," Hamilton added.
In the study, published in the Nature Astronomy journal, the team identified infrared properties similar to those in a type of meteorite called carbonaceous chondrites.
Two types of carbonaceous chondrites called CI and CM chondrites contain several per cent by weight of organic compounds and some also contain water in abundance of 10-15 per cent and as much as 20 per cent in rare cases.
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The presence of volatile organic chemicals and water indicates that they have not undergone substantial heating.
"Because asteroids with hydrated minerals are found throughout the main asteroid belt, significant ice must have been present in the disk during and shortly after the time of carbonaceous asteroid accretion," Hamilton said.
During planetary formation, scientists believe that water was one of the many chemical components that accreted to form Earth. However, most scientists think additional water was delivered in part by comets and pieces of asteroids, including water-bearing carbonaceous meteorites, Hamilton said.
"Many of these meteorites also contain prebiotic organic chemicals and amino acids, which are precursors to the origin of life. The details of water delivery to Earth as well as the larger issue of the different inventories of water ice in the early solar system affect how we view the solar system formation," she explained.
OSIRIS-REx, launched in 2016 to explore Bennu, the smallest body ever orbited by spacecraft, is expected to return a sample of the asteroid to Earth in 2023. Bennu may contain unaltered material from the very beginning of our solar system.
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