Spacecraft drops cargo to Earth after plucking material from asteroid

A space capsule that grabbed rarefragments from the asteroid Bennu came to a "stable rest" in the Utah desert on Sunday, touching down after a mission that began seven years ago, NASA said.

The capsule smoothly descended with a parachuteto its landing zone about four hours after the OSIRIS-RExspacecraft travelled past Earth and released thecargo.

Scientists estimate the capsule holds at least a cup of rubble, or about 250 grams,from the carbon-rich asteroid,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.

OSIRIS-REx had travelled to a crater in the asteroid's northern hemisphere in 2016 and reached it two years later. Once there, it lowered a robotic arm vacuuminto the surface to extract the third and largest sample ever taken from an asteroid in the first mission of its kind for NASA.

Canada had an importantrole to play, providing an instrument called the OSIRIS-REx Laser Altimeter (OLA), whichscanned and measured the surface of the500-metre-wide asteroid, creating a3D model that helped mission planners decide where to land.

Science adviser to the president of the Canadian Space Agency John Moores saidthecontribution means scientists in Canada will have access to a small portion of the asteroid material.

"In total, we laid down more than three billion measurements so this now provides a very highly precise map of the asteroid," said Cameron Dickinson, a staff engineer at Canadian space company MDA Ltd., which designed the Canadian component of the spacecraft.

Japan will also get some of the bounty, after returning to Earth with much smaller samples about a teaspoon of rubble from two other asteroids in 2010 and 2020, giving NASA a portion each time.

2-year analysis

The capsule that sucked up loose rocks and pebbles for NASA landed after a journeyhome of nearly twobillion kilometres.

NASA deployed a team, equipped with helicopters, torecover the capsule from the desert and will transport it toa temporary clean room set up at the U.S. Defense Department's Utah Test and Training Range.

It's estimated the recovery team will need a day to take the capsule apart and prepare the sample for transport to a new lab at NASA's Johnson Space Centre in Houston,where a two-year analysis will take place.The sample will be revealed to the public on Oct.11.

The mission's lead scientist, Dante Lauretta of the University of Arizona, will accompany the sampleto 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.

Bennu, discovered in 1999, is classified as a "near-Earthobject" because it passes relatively close to our planet everysix years. It measures about half a kilometre across and is roughly the size of the Empire State building.

The asteroid is expected to come dangerously close to Earth in 2182 possibly close enough to hit. The data gleaned by OSIRIS-REx will help with any asteroid-deflection effort, according to Lauretta.

Tim Haltigin, planetary senior mission scientist with the Canadian Space Agency, has worked on the project for a decade. Asteroids, he said, are leftover ingredients from the formation of the solar system, and getting a sample from one "is sort of like going back into a cosmic mixing bowl and pulling out individual grains of sugar and a bit of flour and, you know, maybe a chocolate chip."

"And so this is how we're able to study the raw ingredients of the solar system as they were billions and billions and billions of years ago," Haltigin said.

Now free of the sample capsule, OSIRIS-RExis already targeting the asteroid Apophisfor an encounter scheduled for 2029,when the space rock willmakeits closest known flyby of Earth.