There is absolutely nothing inherently special about the asteroid Bennu. A loosely-packed agglomeration of dust and rock about as big across as the Empire State Building and currently 322 million km (200 million mi.) from Earth as it orbits the sun, it is just one of about a million asteroids that astronomers have identified and catalogued. But on Tuesday, Bennu became the most famous asteroid in the solar system, after NASA’s OSIRIS-REx spacecraft made contact with it for a dramatic six seconds to blast loose and collect a sample.
“I must have watched about a hundred times last night,” said Dante Lauretta, the missions’s principal investigator, during a press conference yesterday, while talking about a video clip recorded by the probe during its harrowing maneuver, seen below. “We really did make a mess on the surface of this asteroid, but it’s a good mess.”
NASA/Goddard/University of Arizona
Asteroids are more than just space debris—they are some of the oldest, most pristine samples known of the early solar system. Studying their elemental composition can yield clues to planetary formation, cosmic chemistry and even the emergence of life on Earth. But first you’ve got to get a sample of them, and that’s where OSIRIS-REx—for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer—comes in.
The SUV-sized OSIRIS-REx launched in 2016, arriving at Bennu two years later. It went into orbit around the asteroid, studying it in search of a smooth spot with loose soil and few boulders, making sample collection both easy and safe. But NASA investigators almost immediately realized they were out of luck—Bennu’s surface is almost nothing but boulders. Mission planners hoped for a target site hundreds of feet across, but they settled on one in a region near the asteroid’s north pole that they dubbed Nightingale Crater, which measures just 8 m (26 ft).
Collecting a sample from so small a spot would require both smart technology and deft flying. OSIRIS-REx has a 3.3 meter long, three-jointed arm, at the end of which is a circular sample collector about 0.3 m across dubbed TAGSAM—for Touch and Go Sample Acquisition Mechanism. The flight plan called for the spacecraft to extend its sample arm and then descend from orbit, slowing its speed to just 10 cm/second (0.2 mph) until the TAGSAM assembly made contact with the surface. At that point, nitrogen bottles in the TAGSAM would fire, blasting loose soil and rocks and forcing them into …read more
Source:: Time – Science