2023-09-23 08:18:12
It’s a seven-year journey that should end this Sunday, at least if all goes well. The OSIRIS-REx mission (acronym for Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer) must begin the most delicate phase of its great return, namely bringing a capsule into our atmosphere and landing it in the west the United States. And this, without damaging its precious cargo: material collected from the surface of an asteroid, the first sample of this kind ever collected, and above all brought home.
OSIRIS-REx left Earth on September 8, 2016 from the Cape Canaveral space station, heading for the asteroid Bennu. This asteroid with a diameter of approximately 500 meters and describing an orbit of 1.2 years around the Sun has the particularity of intersecting the Earth’s orbit (we speak of a near-Earth de type Apollon), which made it possible to meet him in just two years. The probe then spent the next two years observing and mapping the space rock.
It was therefore only in 2020 that OSIRIS-REx attempted what had never before been done successfully: descend to the surface of Bennu to collect samples, and then leave again. Its cargo was gathered in an atmospheric re-entry capsule, then our little pioneer (2,110 kg at launch anyway, including 1,230 kg of propellant) then propelled itself towards our Earth using a thrust of its propulsion. This little space container therefore returns to us, after a two-year return journey: arrival scheduled for this Sunday at 4 p.m. universal time.
The building blocks of life
This Sunday, four hours before reaching our planet, the capsule containing the sample will be released. The space probe will then maneuver to avoid Earth and place itself in a stable heliocentric orbit. For its part, the capsule containing the sample will rush towards our planet at 12.2 km/s before braking in our atmosphere, which will increase the temperature of its shield to several thousand degrees. Until the final crash in Utah.
What does it bring us? Only 250g of material taken from Bennu. It doesn’t look like much, but it’s the first time that we’ve recovered this kind of asteroid fragment preserved by the shield of the container, we hope, from combustion in our atmosphere. Enough, perhaps, to understand the beginnings of the solar system, and even to determine the role that carbon-rich asteroids like Bennu may have played in bringing the constituent elements of life to Earth.
NASA will keep 70 percent of the Bennu sample, preserving it “to be studied by scientists not yet born, using technologies not yet invented, to answer questions fundamental on the solar system,” communicated the American agency. The remaining 30% will be distributed to the various international teams behind the mission to be studied today.
New mission: face the snake
As for OSIRIS-REx, its career is not over: the probe must set off again for new adventures towards the asteroid Apophis, a near-Earth asteroid 325 meters in diameter and with a mass of around 40 to 50 million tonnes which crosses twice the Earth in each of its revolutions, which made it classified a time among the most dangerous projectiles for our planet. The OSIRIS-REx mission will then become OSIRIS-APEX, short for OSIRIS-Apophis Explorer. The meeting is scheduled for 2029, when Apophis will pass “only” 31,600 km from our planet.
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