NASA to begin first asteroid sample mission: Seeks 'pristine' specimen
Bennu.... no, not a scientology overlord
NASA is preparing for its first mission that will see a spacecraft retrieve a “pristine sample” of an asteroid so that it can be studied on Earth.
The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft will be launched on 8 September 7:05pm EDT (12:05 am BST) from Cape Canaveral Air Force Station, Florida.
The target asteroid is Bennu, a near-Earth asteroid that was discovered in 1999. It’s around 1,900 feet long - roughly the size of five football fields. NASA chose Bennu for its Earth-like orbit, it has a low eccentricity and inclination, as well as its size and composition.
An extended robotic arm on OSIRIS-REx will scrape more than two ounces of material in 2019, and the sample will be brought back to Earth in a heat-shielded capsule in 2023. The mission - excluding the launch vehicle - will cost $800 million.
OSIRIS-REx weighs in at 2,110kg and will be carrying five main instruments used to study Bennu, including: a camera system to help scientists observe Bennu and pick the best sample site; a laser altimeter, to map the shape of Bennu and determine the distance between the spacecraft and asteroid; and a thermal emission, visible and infrared, and x-ray imaging spectrometer.
Asteroids with diameters less than 200 metres tend to spin more rapidly, and the material on their surface may be ejected in the process. NASA wants to learn more about how the Solar System formed and how life began so it chose Bennu for its slower rotation rates, which increase the likelihood of retaining its carbon-rich surface.
"This asteroid is a time capsule from the birth of our solar system and ushers in a new era of planetary exploration," said Jim Green, director, NASA's Planetary Science Division. "The knowledge from the mission also will help us to develop methods to better track the orbits of asteroids."
NASA will also measure the "Yarkovsky effect" on the asteroid. Asteroids can absorb photons emitted from the Sun and emit them as they radiate the heat away. The photons emitted carry momentum and give the asteroid a recoil kick, which can cause it to travel faster. The small pushes add up over time and can drive an asteroid closer to Earth, making them potentially hazardous.
The OSIRIS-Rex mission is the first US mission that will bring an asteroid sample back to Earth. Another NASA asteroid mission has been commissioned, the Asteroid Redirect Mission (ARM), which will use a robot to obtain an asteroid sample and redirect it into lunar orbit.
The main objective for ARM – which will launch at the end of 2021 – is for NASA to test its robots and spacecraft operations ahead of its larger Journey to Mars mission. ®