NASA spacecraft meets with asteroid
Monday, December 3, 2018(CNN)NASA's OSIRIS-REx mission and the asteroid Bennu have had a date planned for two years, and just after noon ET today, they finally got to meet face to face. OSIRIS-REx fired its thrusters for a small burn, putting it about 4.3 miles from Bennu, marking the end of its journey to the asteroid.
The mission -- which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer -- is NASA's first asteroid sample return mission. It launched in September 2016 and will spend two years up close and personal with Bennu. First images of the asteroid from the spacecraft's perspective have appeared as it got closer and closer.
On Tuesday, the spacecraft will fly within 5 miles of Bennu, which will help design future orbits and map the surface.
Over the next year, OSIRIS-REx will survey the asteroid using five scientific instruments on board the spacecraft. These instruments will help it determine a safe location from which to collect a small sample from Bennu's surface that will be returned to Earth in September 2023.
"Bennu's low gravity provides a unique challenge for the mission," said Rich Burns, OSIRIS-REx project manager at NASA's Goddard Space Flight Center. "At roughly 0.3 mile in diameter, Bennu will be the smallest object that any spacecraft has ever orbited."
The sample from Bennu, a near-Earth asteroid, could help scientists understand not only more about asteroids that could impact Earth but about how planets formed and life began.
OSIRIS-REx has a camera suite, a laser altimeter for 3D mapping, a thermal emission spectrometer to take temperature and mineral content and spectrometers to measure X-rays, nearly infrared and visible light.
An arm mechanism called TAGSAM will reach out to collect the sample from Bennu's surface, making contact with the asteroid for five seconds in July 2020. During this contact, the arm will use a nitrogen gas burst to stir up rock and other materials on the surface so it can capture them. There is enough nitrogen for three attempts if the first is unsuccessful.
NASA said the estimated 2.1-ounce sample size equates to about 30 sugar packets worth of dirt and rocks.
The arm has a full range of motion, with joints capable of movement comparable to shoulder, elbow and wrist joints. It was "flexed" in space for the first time on November 14.
"The TAGSAM exercise is an important milestone, as the prime objective of the OSIRIS-REx mission is to return a sample of Bennu to Earth," said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. "This successful test shows that, when the time comes, TAGSAM is ready to reach out and tag the asteroid."
Source: https://www.cnn.com/2018/12/03/world/osiris-rex-bennu-asteroid-mission-rendezvous/index.html