Nasa’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) asteroid-hunting mission has discovered water on the asteroid Bennu.

Data sent by the space agency’s first asteroid sample return mission has shown that water is locked inside the clays of Bennu.

The data was transmitted by OSIRIS-REx’s two spectrometers, the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) and the OSIRIS-REx Thermal Emission Spectrometer (OTES), to the Nasa team handling the mission on Earth.

It was revealed that molecules containing oxygen and hydrogen atoms, known as ‘hydroxyls’, exist on Bennu.

“When samples of this material are returned by the mission to Earth in 2023, scientists will receive a treasure trove of new information about the history and evolution of our solar system.”

Nasa believes that hydroxyls are present in water-bearing clay minerals across Bennu, which means that the asteroid’s rocky material came into contact with water at some point.

Bennu is, however, too small to accommodate liquid water, but the latest data show that it existed at some time on its parent body, which is a much larger asteroid.

Nasa Goddard Space Flight Center OVIRS deputy instrument scientist Amy Simon said: “The presence of hydrated minerals across the asteroid confirms that Bennu, a remnant from early in the formation of the solar system, is an excellent specimen for the OSIRIS-REx mission to study the composition of primitive volatiles and organics.

“When samples of this material are returned by the mission to Earth in 2023, scientists will receive a treasure trove of new information about the history and evolution of our solar system.”

OSIRIS-REx is currently conducting a preliminary survey of the asteroid by flying itself in passes over the asteroid’s equator, north and south poles at ranges around 7km to better calculate the asteroid’s mass.

Launched in September 2016, OSIRIS-REx is scheduled to perform its first orbital insertion on 31 December.

The spacecraft is expected to remain in orbit until it exits to begin another series of flybys for its next round of survey next February.