Asteroid OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) is the latest in a string of missions that have attempted to retrieve some decent-sized samples of asteroid dirt. Previous missions brought back some very disappointingly small samples.
The OSIRIS-REx spacecraft will take two years to reach asteroid Bennu by September 2019, according to CTV News. There, the spacecraft will have to slow way down to a crawl, relatively speaking. Actually, the asteroid and the spacecraft will be hurtling around the sun at 63,000 mph by then. OSIRIS-REx will then go into a one-mile-high orbit around Bennu.
At 493 meters (1,617 feet) wide, and about the size of the Empire State Building, Bennu will be the smallest object NASA has ever tried to orbit around. One thing the scientists do have to contend with is the low gravity, solar winds, and pressures from solar and re-emitted infrared radiation. All of these things could affect the orbit.
To that end, OSIRIS-REx is equipped with an array of 28 different thrusters on board, including a pair of extra small thruster engines that will allow navigators here on Earth to have fine-tuned control of the spacecraft while it pinpoints with photographs the areas to sample. “Kind of like photographic breadcrumbs,” says mission design lead, Brian Sutter, of Lockheed Martin, reports Wired.
Back in 2011, the Canadian Space Agency (CSA) collaborated with NASA on this, the first U.S. mission to collect a sample of an asteroid and return it to Earth. Scientists looked to Canada for the special laser instrument and expertise needed to study the geology of the asteroid.
The instrument, called OLA (OSIRIS-REx Laser Altimeter) is an advanced LIDAR (Light Detecting and Ranging) system that will scan the entire surface of the asteroid. Along with other instruments, OLA will be creating detailed 3-D maps of every crack, canyon, and open space, providing details about the topography and interior geology of the space rock.
The process of scanning the entire surface of Bennu using OLA will take six months. After OLA’s data and pictures have been studied, scientists will determine the best places to move in and “gently” pluck samples from the asteroid’s surface using a robotic arm. This step will also have to be done very cautiously.
There is only enough nitrogen on board to make three sampling attempts, and if all goes well, 2.1 ounces (about four tablespoons) of asteroid material will be stored in a capsule for its journey back to Earth. In September 2023, if the heat shield protects the capsule, the parachute opens, and the well don’t run dry, the prized asteroid dust will land in the desert in Utah.
