Traces of water found on the asteroid Bennu


NASA’s OSIRIS-REx probe is not wasting its time. A week after arriving in the orbit of the asteroid Bennu, it has already detected traces of water on the celestial pebble. Indeed, the two spectrometers (OVIRS and OTES) on OSIRIS-REx revealed the presence of hydroxyl, molecules that contain oxygen and hydrogen.

According to the mission’s scientific team, these molecules are found in hydrated clay minerals, which means that at some point the rock material interacted with water.

The presence of hydrated minerals on Bennu confirms that the asteroid is a remnant of the beginning of the formation of the solar system, and that it is an excellent specimen for the OSIRIS-REx mission aimed at studying the composition of primitive organic and volatile matter.

Dr. Amy Simon, NASA

This detection thus confirms the scientists’ interests in Bennu who chose it among 7000 asteroid candidates.

It also shows that the asteroid has remained almost unchanged since the formation of the solar system 4.6 billion years ago. By studying this witness of the carbon-rich past, researchers hope to deepen their knowledge of this very distant time, and perhaps to discover the elements of life on Earth that could have fallen on our planet.

This discovery also seems to show a connection between what we think has happened in space with asteroids like Benou and what we see in the terrestrial meteorites analyzed in the laboratory.

 Dr. Ellen Howell, University of Arizona

In addition, the three OCAMS cameras of the spacecraft have begun mapping the asteroid, making high-resolution photos, and documenting the site selected for sampling and filming. The information gathered to date corroborates radar observations from the Earth on its diameter, rotational speed, inclination, and overall shape.

OSIRIS-REx has traveled more than two years to get closer to Bennu, which revolves around the Sun at a speed of 100,000 km/h and is currently 124 million kilometers from the Earth. In early December, the small US probe braked to stabilize at 7 km from the asteroid. Never has a human probe entered into orbit around such a small asteroid.

The asteroid is also not quite spherical, it is wider than “high”, its shape does not have the round regularity of a planet.

In mid-2020, Osiris-Rex will move closer, “at the walking pace of an insect”, deploy an articulated arm and touch the surface for five seconds to suck 60 grams to 2 kg of material.

The probe will begin its return to the Earth in March 2021.

Emy Torres

Emy holds a degree in Political Science from the University of Michigan and currently freelances part-time for The Talking Democrat.