After traveling through space for more than two years and 1.2 billion miles (2 billion km), NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) spacecraft arrived at its destination — asteroid Bennu (formerly 1999 RQ36) — on December 3, 2018.
Launched on September 8, 2016, OSIRIS-REx is NASA’s mission to explore the near-Earth asteroid Bennu, collect a sample and return it to Earth.
Now, at about 11.8 miles (19 km) from Bennu’s Sun-facing surface, the spacecraft will begin a preliminary survey of the asteroid.
It will commence flyovers of Bennu’s north pole, equatorial region, and south pole, getting as close as nearly 4 miles (7 km) above Bennu during each flyover.
The primary science goals of this survey are to refine estimates of the asteroid’s mass and spin rate, and to generate a more precise model of its shape. The data will help determine potential sites for later sample collection.
OSIRIS-REx will enter orbit around Bennu on December 31 — thus making this asteroid, which is only about 1,600 feet (492 m) across — the smallest object ever orbited by a spacecraft.
“During our approach toward Bennu, we have taken observations at much higher resolution than were available from Earth,” said OSIRIS-REx project manager Dr. Rich Burns, of NASA’s Goddard Space Flight Center.
“These observations have revealed an asteroid that is both consistent with our expectations from ground-based measurements and an exceptionally interesting small world.”
“Now we embark on gaining experience flying our spacecraft about such a small body.”
When OSIRIS-REx begins to orbit Bennu at the end of this month, it will come close to approximately three quarters of a mile (1.25 km) to its surface.
In February 2019, the spacecraft will begin efforts to globally map Bennu to determine the best site for sample collection.
After the collection site is selected, the spacecraft will briefly touch the surface of Bennu to retrieve a sample.
OSIRIS-REx is scheduled to return the sample to Earth in September 2023.