Last Friday, OSIRIS-REx captured imagery over the course of a four-hour, 11-minute period to take in a full rotation of the diamond-shaped space rock from a distance of about 122 miles.
The view is whetting astronomers’ appetite for even closer looks at Bennu, which is currently about 80 million miles from Earth. Over the next few weeks, OSIRIS-REx will carefully survey the quarter-mile-wide asteroid’s terrain as it edges closer. During December, it’ll execute three flybys, coming within just a few miles of the surface. And early next year, it’ll settle into a close-in orbit and conduct a months-long survey.
All that’s just a buildup for the main event: the probe’s descent to the surface in mid-2020 for the collection of samples that will be packed up for delivery to Earth in 2023.
The principal investigator for the OSIRIS-REx mission, Dante Lauretta of the University of Arizona’s Lunar and Planetary Laboratory, was struck by Bennu’s variations in surface reflectance, which hints at a diverse composition: “Those dark areas have got the team buzzing with excitement!” Lauretta tweeted.
Now with full coverage – here is a complete rotation of Bennu with the colors stretched to accentuate the reflectance variations. pic.twitter.com/8hD9XMPsS8
— Dante Lauretta (@DSLauretta) November 6, 2018
There’s also a boulder in Bennu’s southern hemisphere that looks as if it’s “just hanging on” due to the asteroid’s weak gravitational pull, Lauretta said in a different tweet.
These features add to the intrigue surrounding the OSIRIS-REx mission, which is expected to provide insights into how the solar system was formed, how potentially threatening asteroids can be diverted, and how future space explorers can take advantage of what asteroids have to offer. For what it’s worth, OSIRIS-REx is a tortured acronym that stands for Origins, Spectral Interpretation, Resource Identification, Security – Regolith Explorer.
OSIRIS-REx isn’t the only game in town when it comes to asteroid exploration: Japan’s Hayabusa 2 probe is in the midst of its own survey of another diamond-shaped asteroid that looks a lot like Bennu, only twice as wide. Hayabusa 2 is due to grab bits of asteroid Ryugu next year and bring them back to Earth in 2020, well before OSIRIS-REx’s delivery.