Nasa capsule returns to Earth with long-awaited rare asteroid sample

Nasa's first asteroid samples fetched from deep space parachuted into the Utah desert on Sunday to cap a seven-year journey.

In a flyby of Earth, the Osiris-Rex spacecraft released the sample capsule from 100,000km out. The small capsule landed four hours later on a remote expanse of military land, as the mothership set off after another asteroid.

Scientists estimate the capsule holds at least a cup of rubble from the carbon-rich asteroid known as Bennu, but won’t know for sure until the container is opened. Some spilled and floated away when the spacecraft scooped up too much and rocks jammed the container’s lid during collection three years ago.

Japan, the only other country to bring back asteroid samples, gathered about a teaspoon in a pair of asteroid missions.

The pebbles and dust delivered on Sunday represent the biggest haul from beyond the Moon. Preserved building blocks from the dawn of our solar system 4.5 billion years ago, the samples will help scientists better understand how Earth and life formed.

Osiris-Rex, the mothership, rocketed away on the $1 billion mission in 2016. It reached Bennu two years later and, using a long stick vacuum, grabbed rubble from the small roundish space rock in 2020. By the time it returned, the spacecraft had logged 4 billion miles (6.2 billion kilometers).

NASA’s recovery effort in Utah included helicopters as well as a temporary clean room set up at the Defense Department’s Utah Test and Training Range. The samples will be flown Monday morning to a new lab at Nasa's Johnson Space Center in Houston. The building already houses the hundreds of pounds (kilograms) of moon rocks gathered by the Apollo astronauts more than a half-century ago.

The mission’s lead scientist, Dante Lauretta of the University of Arizona, will accompany the samples to Texas. The opening of the container in Houston in the next day or two will be “the real moment of truth,” given the uncertainty over the amount inside, he said ahead of the landing.

Engineers estimate the canister holds 250 grammes of material from Bennu, plus or minus 100 grammes. Even at the low end, it will easily surpass the minimum requirement of the mission, Lauretta said.

It will take a few weeks to get a precise measurement, said Nasa’s lead curator Nicole Lunning.

Nasa plans a public show-and-tell in October.

Currently orbiting the sun 50 million miles (81 million kilometers) from Earth, Bennu is about one-third of a mile (one-half of a kilometer) across, roughly the size of the Empire State Building but shaped like a spinning top. It’s believed to be the broken fragment of a much larger asteroid.

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