A NASA space explorer on Tuesday (October 20) touched down on the surface of the asteroid Bennu to collect rock samples and return them to Earth for study in what would be the first such mission for the U.S. space agency.

OSIRIS-REx is a seven-year mission that is set to conclude upon the delivery to Earth of at least 60 grams of the asteroid’s rocky material in 2023, which is expected to provide fresh insights into the formation of the solar system and the origin of life.

Image of the NASA space explorer OSIRIS-REx touching down on the asteroid Bennu. (Image courtesy of NASA)(Kyodo)

The U.S. team plans to exchange the samples with those to be brought back from asteroid Ryugu by Japan’s space probe Hayabusa2, which is due to return to Earth at the end of this year.

The OSIRIS-REx spacecraft arrived above Bennu in December 2018 after traveling through space for over two years, covering more than 2 billion kilometers. It has since been conducting surveys and preparing for the sample collection, such as by carrying out rehearsal operations.

On Tuesday, the spacecraft, which is the size of a 15-passenger van, touched down on Bennu’s surface briefly by extending its robotic arm to a rocky site surrounded by building-sized boulders, according to NASA.

The sample collector attached at the end of the arm has a function to release nitrogen gas to stir up and lift rocks and dust for capture.

According to the team, indications regarding the success of the collection attempt and the spacecraft’s performance will not be available until imagery starts coming in on Wednesday. It is also expected to take about 10 days to know how much material was retrieved.

NASA intends to obtain a sample of between 60 grams and 2 kilograms. Hayabusa2, which is smaller than the OSIRIS-REx craft, has aimed to collect 0.1 gram of material.

The mission, if it goes successfully, will be the first U.S. mission to carry samples from an asteroid back to Earth and the largest sample returned from space since the Apollo era, according to the National Aeronautics and Space Administration.

The Apollo missions between 1969 and 1972 brought back 382 kilograms of moon rock, pebble and stone samples.

Asteroids are known as the remnants left over from the early formation of the solar system about 4.6 billion years ago.

Bennu, a diamond-shaped asteroid measuring 500 meters in diameter, has been mostly undisturbed for billions of years and is believed to retain materials from the early solar system, according to NASA. It may also contain organics necessary to form life.


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