OSIRIS -REx has hit the target: the probe sent by NASA to collect dust and samples from the asteroid Bennu smoothly deployed his robotic arm and, for the first time ever, briefly touched a body celestial, collecting precious material from the surface that will be sent to our Planet in the 2023 (the 24 September e) to be analyzed. OSIRIS-Rex left Cape Canaveral on September 8 2016 and crossed paths with the lonely Bennu on December 3 2018, to start orbiting the 31 December 2018.

Benne is an asteroid currently located at 321 millions of kilometers from Earth and according to scientists it is so ancient that it offers us a “ window into the early solar system “, when the Universe we know was starting to take shape by spreading “ingredients” essential to creating life. If OSIRIS-Rex’s “hit and run” on Bennu , known more precisely as “Touch-And -Go “(TAG), has collected enough material , the probe will start its return trip in March 2021 . Otherwise there will be a new attempt to obtain the necessary samples on 12 January.

The “contact”

Alla 19: 50 yesterday Italian time, OSIRIS-REx turned on its thrusters to move out of Bennu’s orbit. He then extended his long arm by 3 , 35 meters , called the “Touch-And-Go Sample Acquisition Mechanism” (TAGSAM), and began its descent of 805 meters towards the surface. After four hours, at an altitude of approximately 55 meters, the probe performed a maneuver in two parts to arrive precisely to the sample collection site, known as “Nightingale”.

Ten minutes later, the probe turned on the thrusters to slowly approach and adapt to the rotation of the asteroid . To do this he skirted for 11 minutes a boulder the size of a two-story building nicknamed “Mount Doom”, landing in a clear spot inside a crater in the Northern Hemisphere by Bennu . The Nightingale site, according to NASA, is one of the few relatively clear (hence favorable for dust and sample collection) points on an asteroid covered with boulders. The data sent by the telemetry says that the TAG event happened successfully (and autonomously, with pre-programmed instructions from the engineers on Earth) , but it will take about a week to understand if OSIRIS-REx has collected the required amount of samples: at least 60 grams . Real-time data says the arm made contact with the surface and “fired” nitrogen to raise dust and samples on Bennu’s surface , some of which should have been captured. Shortly after the operation the spacecraft safely departed from Bennu.

“ Today’s TAG maneuver is historic “, said Lori Glaze, director of the Planetary Science Division of NASA’s Washington headquarters. “The fact that we have safely and successfully touched the surface of Bennu, plus all the other milestones this mission has already achieved, is a testament to the fervent spirit of exploration that continues to uncover the secrets of the solar system.”

Everything went fine? There is a plan B

To understand if OSIRIS-REx has collected the right amount of samples, NASA engineers will use different techniques , in order to make estimates as accurate as possible from a distance. First, they’ll compare images from the Nightingale site before and after the event, to see how much surface material has shifted. Next, the team will take a picture of the TAGSAM arm head, where the samples should be crammed, with a camera called SamCam, dedicated to documenting the collection process. An indirect indication will be the amount of dust found around the head. OSIRIS-REx engineers will also attempt to take photos which could, provided you have the right lighting conditions, show the inside of the head.

A couple of days after analyzing the images taken by the SamCam, the spacecraft will try yet another method to measure the mass of the collected sample, in order to determine the change in the spacecraft’s “moment of inertia”, ie how the mass is. and how it affects the rotation of the body around a central axis. This maneuver will involve extending the TAGSAM arm towards the side of the vehicle and slowly rotating it around an axis perpendicular to the arm. “This technique,” explains NASA, “is analogous to a person spinning with one arm extended while holding a string with a ball at the end. The person can sense the mass of the ball from the tension in the string. By performing this maneuver before the ‘TAG event and later engineers can measure the change in the mass of the head as a result of the sample inside “.

If all analyzes and tests dimos