NASA's Osiris-Rex mission is ready to take samples from the asteroid Bennu

The space mission is about to hit Bennu's ground. It will be possible to observe the maneuver live from our 23 on 20 October

The Osiris-Rex mission in the recent ground approach tests by Bennu (photo: Nasa / Goddard / University of Arizona) The Osiris-Rex mission of NASA, in orbit around the asteroid Bennu since December 2018, it is about to approach the ground and take a sample from its surface, in the so-called Touch-and-go maneuver (in acronym Tag), and subsequently, in 2023, bring it back to Earth for studies in-depth. The exciting touch of Osiris-Rex is scheduled for the night between Tuesday 20 and Wednesday 21 October and will precisely take place at 12.12am on the 21st (just after midnight). The event will be broadcast live by NASA and on the Osiris-Rex Twitter channel. The broadcast will begin earlier, at 11 pm on October 20, when the descent and landing operations will begin.

The Osiris-Rex stages

After a two-year journey in space, in the December 2018 the Osiris-Rex mission reached the asteroid Bennu and stopped around the celestial body, currently located 288 million kilometers from Earth. Upon arrival, the mission did not land on Bennu but was positioned at a height of 24 kilometers. From 2018 to 2020 he carried out several studies and even some approaches (in the image): on 11 August 2020, for example, Osiris-Rex reached a distance of only 40 meters from the Nightingale crater (nightingale in English), the site of the future sampling, near the north pole of Bennu. It took NASA months to choose, among the four candidate sites, this crater, with a diameter of about 20 meters, rather regular and intact, composed of a fine-grained ground, while the rest and the surrounding part is full of boulders, for this ideal for picking up material.

The descent and the touch

Overall, the operation will last about 4 and a half hours, as NASA explains. Initially Osiris-Rex will fire up its thrusters to move from the distance it is at, less than a kilometer from the surface of Bennu, and initiate the descent. After a 4-hour journey, the spacecraft will stop and make a stop at about 125 meters above sea level, preparing for the further approach. At a height of about 54 meters it will adjust its path in order to take aim to cross the path of the rotating asteroid at the moment of contact. The touch is very short and will last less than 16 seconds in total, while Osiris-Rex will fire a charge of pressurized nitrogen to move the ground and be able to collect the sample.

Appointments to attend the operations

To find out what will happen and how the operations will take place on Tuesday 20 October 2020 there will be an animation in live streaming, from 19.20 to 00.30 on the site of the Osiris-Rex mission.

From 23 of 20 to 00.30 on 21 October there will be the direct, made possible by the Lockheed Martin Space company, of the descent into the Nightingale crater on Bennu with the first attempt of the mission - which we hope will go to port - to collect dust and soil samples from Bennu. Furthermore, from midnight to 00.30 am on the 21st, the experts will answer questions from the public about Touch-and-go, asteroid science and Osiris-Rex: to participate you must use the #ToBennuAndBack tag.

The evidence collected so far

Among the evidence obtained in the first investigations, the presence of OH molecules trapped in the minerals was observed, a sign of possible traces of water perhaps present in the past. In addition, there are carbon-rich organic molecules that can provide clues to understand if and how this ancient asteroid, along with others, played a role in spreading the chemical elements underlying life on Earth. The scientists then collected various images of Bennu's conformation and terrain, which is littered with an enormous amount of smaller rocks, surprisingly dominated by gigantic boulders.