Excitement as Nasa’s first asteroid sample – world’s biggest – parachutes into Utah desert

The final descent and landing, shown on a Nasa livestream, capped a six-year joint mission between the US space agency and the University of Arizona. It marked only the third asteroid sample, and by far the biggest, ever returned to Earth for analysis, following two similar missions by Japan’s space agency ending in 2010 and 2020.

OSIRIS-REx collected its specimen three years ago from Bennu, a small, carbon-rich asteroid discovered in 1999. The space rock is classified as a “near-Earth object” because it passes relatively close to our planet every six years, though the odds of an impact are considered remote.

Apparently made up of a loose collection of rocks, like a rubble pile, Bennu measures just 500 metres (1,600ft) across, making it slightly wider than the Empire State Building is tall but tiny compared with the Chicxulub asteroid that struck Earth some 66 million years ago, wiping out the dinosaurs.

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Like other asteroids, Bennu is a relic of the early solar system. Because its present-day chemistry and mineralogy are virtually unchanged since forming some 4.5 billion years ago, it holds valuable clues to the origins and development of rocky planets such as Earth.

It may even contain organic molecules similar to those necessary for the emergence of microbes.

Samples returned three years ago by the Japanese mission Hayabusa2 from Ryugu, another near-Earth asteroid, were found to contain two organic compounds, buttressing the hypothesis that celestial objects such as comets, asteroids and meteorites that bombarded early Earth seeded the young planet with the primordial ingredients for life.

OSIRIS-REx launched in September 2016 and reached Bennu in 2018, then spent nearly two years orbiting the asteroid before venturing close enough to snatch a sample of the loose surface material with its robot arm on October 20, 2020.

The spacecraft departed Bennu in May 2021 for a 1.2-billion-mile (1.9-billion-km) cruise back to Earth, including two orbits around the sun.

Hitting the upper atmosphere at 35 times the speed of sound about 13 minutes before landing, the capsule glowed red hot as it plunged earthward and temperatures inside the vessel were expected to reach 5,000 degrees Fahrenheit (2,800°C).

Parachutes deployed near the very end of the descent, slowing the capsule to about 11mph before it fell gently onto the desert floor of northwestern Utah.

The Bennu sample has been estimated at 250 grams (8.8 ounces), far surpassing the 5 grams carried back from Ryugu in 2020 or the tiny specimen delivered from asteroid Itokawa in 2010. But the amount of material delivered on Sunday will not be more precisely quantified for at least a week.

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A recovery team of scientists and technicians were standing by to retrieve the capsule, and to confirm whether the integrity of the vessel and inner canister bearing the asteroid material were maintained through re-entry and landing. They aimed to keep the sample pristine and free of any terrestrial contamination.

Once the capsule has been secured, the sample will be flown by helicopter to a “clean room” at the Utah test range for initial examination, then transported to Nasa’s Johnson Space Centre in Houston, to be parcelled into smaller specimens promised to some 200 scientists in 60 laboratories around the world.

The main portion of the OSIRIS-REx spacecraft, meanwhile, is expected to sail on to explore yet another near-Earth asteroid, named Apophis.