NASA on Monday said the asteroid Bennu was once in contact with water, based on molecules containing hydrogen and oxygen bonded together detected by the OSIRIS-Rex spacecraft in numerous places on the asteroid. 

Bennu may have once belonged to a much larger asteroid that carried water, the agency announced in a press release, adding these measurements are a promising start for the OSIRIS-Rex mission to solve the mystery of how the solar system formed. Scientists aim for OSIRIS-Rex, short for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, to collect a sample from the asteroid’s surface and return it to Earth in 2023.

“Scientists will receive a treasure trove of new information about the history and evolution of our solar system,” said Amy Simon, a deputy instrument scientist at NASA’s Goddard Space Flight Center.

NASA made this announcement about molecular traces of water on the asteroid after analyzing images and light measurements collected by three of the spacecraft’s instruments during its initial flight toward Bennu. Simon is part of the team analyzing data from one of the spacecraft’s spectrometers called OVIRS, short for the OSIRIS-REx Visible and Infrared Spectrometer. By combining that data with information from the OSIRIS-REx Thermal Emission Spectrometer and the OSIRIS-REx Camera Suite, Simon and other scientists detected these molecules called “hydroxyls” in clay minerals across the asteroid. 

The spacecraft made its first flight near Bennu on Dec. 3, and controllers are flying the spacecraft within 7 kilometers over its north pole, equator, and south pole to measure the mass and potential gravitational pull of the asteroid. NASA expects controllers will insert the spacecraft into orbit around Bennu on Dec. 31, and keep it in orbit through February while searching for a place to touch down briefly on the surface and collect a sample.

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