The American probe Osiris-Rex definitively left the orbit of the asteroid Bennu on Monday, May 10, from which it collected dust samples last year, to begin its journey back to Earth.
There will still be a long way to go: it will not land in the desert of Utah, in the United States, until September 24, 2023. The probe
"is now traveling at more than 950 km / h from Bennu, on its way home. "
Said Dante Lauretta, head of the mission, on the video broadcast of the event by NASA.
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The propellants of the machine were engaged without incident for seven minutes in order to carry out the necessary thrust to put the probe on the correct trajectory.
The latter will cross that of the Earth after a final journey of 2.3 billion kilometers.
Osiris-Rex brings back on board
“more than 60 grams”
of dust and fragments of the asteroid, that is to say the largest sample collected by NASA from the lunar rocks brought back by the Apollo missions.
To achieve this result, the US Space Agency carried out a high-risk operation in October 2020: the probe came into contact with the ground of the asteroid for a few seconds, and the dust was raised by a nitrogen blast. tablet before being captured.
Surprise: the probe's arm had sunk several centimeters into the surface of the asteroid, which scientists learned was in reality
"very sparsely formed"
, said Dante Lauretta.
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And everything had almost failed when NASA realized a few days later that the valve of the collection compartment was failing to close, letting fragments escape into space. But the cargo had finally ended up being secured, being transferred from the probe arm into the capsule, fixed in its center.
In two and a half years, this capsule will be released a few hours before it enters the Earth's atmosphere, and will be slowed down by a parachute system for its landing. The samples will then be transported to NASA's Johnson Space Center in Houston, but 75% will be kept intact
"to be studied by future generations with technologies that are not yet created,"
the agency said. Their analysis should help scientists better understand the formation of the solar system and the development of Earth as a habitable planet.