Scientists have high hopes for the sample, saying it will provide a better understanding of the formation of our solar system and how Earth became habitable.
The Osiris-Rex probe’s final, fiery descent through Earth’s atmosphere will be perilous, but the US space agency is hoping for a soft landing, around 9:00am local (15H00 GMT), in a military test range in northwestern Utah.
Four years after its 2016 launch, the probe landed on the asteroid Bennu and collected roughly nine ounces (250 grams) of dust from its rocky surface.
Even this small amount of dust, NASA claims, will “help us understand the types asteroids which could pose a threat to Earth”, and shed light on “the earliest history of the solar system”, NASA Administrator Bill Nelson stated.
“This return of the sample is historic,” NASA scientist Amy Simon said to AFP. “This is going to be the biggest sample we’ve brought back since the Apollo moon rocks” were returned to Earth.
But returning the capsule will be “a dangerous manoeuvre,” acknowledged she.
Osiris-Rex is set to release the capsule — from an altitude of more than 67,000 miles (108,000 kilometers) — some four hours before it lands.
The fiery passage through the atmosphere will come only in the last 13 minutes, as the capsule hurtles downward at a speed of more than 27,000 miles per hour, with temperatures of up to 5,000 Fahrenheit (2,760 Celsius).
Its rapid descent, monitored by army sensors, will be slowed by two successive parachutes. If they do not deploy properly, it will result in a “hard land”.
If it appears that the target zone (37 by 9 miles) might be missed, NASA controllers could decide at the last moment not to release the capsule.
The probe would then keep its cargo and make another orbit of the sun. The scientists would need to wait for 2025 in order to try a second landing.
Successful landings would lead Osiris Rex to another asteroid.
Once the tire-sized capsule touches down in Utah, a team in protective masks and gloves will place it in a net to be airlifted by helicopter to a temporary “clean room” nearby.
NASA wants this done as quickly and carefully as possible to avoid any contamination of the sample with desert sands, skewing test results.
If all goes according to plan, on Monday the NASA Johnson Space Center will receive the test sample by air. The box is opened there in a second “clean room”, which begins a long process.
NASA plans to announce its first results at a news conference October 11.
Most of the sample will be conserved for study by future generations. Roughly one-fourth of it will be immediately used in experiments, and a small amount will be sent to Japan and Canada, partners in the mission.
Japan gave NASA some grains of dust from Ryugu after it brought 0. 2 ounce of dust to Earth in 2020 during the Hayabusa-2 mission. It had returned a tiny amount of dust from an asteroid ten years earlier.
But the sample from Bennu is much larger, allowing for significantly more testing, Simon said.
Earth’s origin story
Asteroids are composed of the original materials of the solar system, dating to some 4. 5 billion years ago, and have remained relatively intact.
They “can give us clues about how the solar system formed and evolved,” said Osiris-Rex program executive Melissa Morris.
“It’s our own origin story.”
By striking Earth’s surface, “we do believe asteroids and comets delivered organic material, potentially water, that helped life flourish here on Earth,” Simon said.
Scientists believe Bennu, which is 1,640 feet in diameter, is rich in carbon — a building block of life on Earth — and contains water molecules locked in minerals.
Bennu had surprised scientists in 2020 when the probe, during the few seconds of contact with the asteroid’s surface, had sunk into the soil, revealing an unexpectedly low density, sort of like a children’s pool filled with plastic balls.
Understanding its composition could come in handy in the — distant — future.
For there is a slight, but non-zero, chance (one in 2,700) that Bennu could collide catastrophically with Earth, though not until 2182.
Last year, NASA was able to alter the trajectory of an asteroid in test by smashing a probe against it. It may need to do this again in the future with more serious stakes.
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