Graphic shows spacecraft, touch-and-go robotic arm and sample return capsule.


OSIRIS-REx mission to asteroid Bennu

By Duncan Mil

January 24, 2019 - The OSIRIS-REx spacecraft will touch down in 2020 to collect a sample from the surface of Bennu -- a carbon-rich asteroid which may contain the molecular precursors to the origin of life on Earth.

Of more than 500,000 asteroids in the solar system, Bennu is one of only five with the right orbits, sizes and carbonaceous compositions for a sample-return mission. The 510-metre wide asteroid is probably part of a much more massive asteroid -- remaining debris from the formation of the solar system some 4.6 billion years ago.

Launched in September 2016, OSIRIS-REx arrived at Bennu, 110 million kilometres from Earth, in December 2018. On New Year’s Eve, the spacecraft went into orbit around Bennu.

Starting in February, the OSIRIS-REx team will perform a series of close flybys of Bennu, taking high-resolution images of the asteroid to select a sampling site.

During the summer of 2020, the spacecraft will briefly touch the surface of Bennu using a two-metre-long robotic arm, its Touch-and-Go Sample Arm Mechanism (TAGSAM) to retrieve a sample.

The sample head will use high-pressure nitrogen to kick up regolith -- dust and rock particles from millions of years of meteoroid impacts -- during a five-second contact. The TAGSAM can capture particles up to two centimetres in diameter while contact pads can pick up fine dust particles up to one millimetre in diameter.

The OSIRIS-REx team hope to collect up to two kilograms of regolith. The sample will be sealed in a return capsule for the cruise back to Earth, arriving in September 2023.

PUBLISHED: 24/01/2019; STORY: Graphic News; PICTURES: NASA/JPL
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