Following a two-year journey, NASA's OSIRIS-REx spacecraft is beginning to close in on its target, the primitive asteroid Bennu. As part of its preparations for this highly anticipated encounter, mission control has successfully carried out an important dress rehearsal starring the robotic arm that will be used to grab samples of dust and rock from the surface.

With Bennu zipping around the Sun at an average speed of 101,000 km/h (63,000 mph), OSIRIS-REx is currently completing a series of careful braking maneuvers as it makes its way toward the asteroid. Scheduled to enter its orbit on December 3, OSIRIS-REx will spend almost a year surveying the asteroid and picking out the best location pull its sample from.

The instrument it will use to grab that sample is called the Touch-and-Go Sample Acquisition Mechanism (TAGSAM). Designed and built by Lockheed Martin over more than a decade, the 11-ft (3.35-m) arm features three articulating joints, a rounded sampling head and three bottles of high-pressure nitrogen gas.

In October, OSIRIS-REx jettisoned the cover off the TAGSAM arm and left it in a resting position for a few weeks. It was then fully deployed into its sampling position with images, seen above, confirming that it extended and retracted just as it was designed to do. This is the first time the TAGSAM arm has been deployed in the micro-gravity environment of space.

"The team is very pleased that TAGSAM has been released, deployed, and is operating as commanded through its full range of motion," says Rich Burns, OSIRIS-REx project manager at NASA's Goddard Space Flight Center. "It has been restrained for over two years since launch, so it is gratifying to see it out of its shackles and performing well."

Sometime in the early 2020s, TAGSAM will go in for the kill. It will blast the surface of Bennu with its nitrogen gas to stir up material and use the TAGSAM head to capture around 2.1 oz (60 g) of regolith. This is expected to take around five seconds, before OSIRIS-REx retreats and starts to make its way back to Earth.

"Now that we have put TAGSAM through its paces in space and know it is ready to perform at Bennu, we can focus on the challenges of navigating around the asteroid and seeking out the best possible sample site," says Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson.

You can see a demonstration of OSIRIS-REx's sampling operations in the video below.

Source: NASA

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