The OSIRIS-REx spacecraft, launched in September 2016, is closing in on its target of the Bennu asteroid. And on October 16 NASA confirmed that an important step had been taken: the craft unfurled its robotic arm and tested it to confirm it is ready to go when it reaches the asteroid.
The robotic arm is formally called the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) and is an essential component in the craft’s mission to collect a sample from the asteroid. The arm had to be tested by flexing it through its full range of motion and making sure that all of the joints worked correctly. The successfully completion of the arm testing was confirmed through telemetry data and images taken by the SamCam camera on board the craft.
The arm consists of three articulating joints, a sampler head which collects the sample and looks roughly like a car’s air filter, and three bottles of nitrogen gas kept at high pressure. It was designed by aerospace company Lockheed Martin to “tag” the asteroid by maneuvering the craft nearby and then unfurling the arm to collect a sample. The nitrogen gas included in the arm will be blasted down onto the asteroid’s surface to stir up the dirt and rocks there which will then be caught by the sampler head — sort of like a vacuum cleaner. The particles collected will be stored in a canister and the nitrogen will be allowed to escape, leaving a sample of between 60 and 2,000 grams of material for study and examination. The process of collection should only take around 5 seconds, and then the spacecraft will perform careful maneuvers to back up away from the asteroid and head home.
OSIRIS-REx should arrive at Bennu in around two weeks’ time and then will prepare to collect a sample of rock and dirt from its surface in July 2020. Once a sample has been collected, the craft will turn around and deliver it back to Earth, hopefully arriving in the west desert of Utah in 2023. The sample could shed light on the early formation of the solar system as the asteroid is extremely old — older even than the solar system itself.