Asteroids, Comets and Asteroids

Just Passing By: the Globe of Earth Imaged by OSIRIS-REx

Posted by Jason Major on
Earth imaged on Sept. 22, 2017 by the MapCam instrument aboard OSIRIS-REx. Credit: NASA/Goddard/University of Arizona

Here’s our beautiful blue marble as seen by NASA’s OSIRIS-REx spacecraft on Sept. 22, 2017 from a distance of 106,000 miles (170,000 km). It had just completed a gravity-assist flyby of Earth—a little 19,000 mph “once around the block” that gave the spacecraft an 8,500-mile-an-hour speed boost necessary to adjust its course toward Bennu, the asteroid target of its mission.

OSIRIS-REx launched from Cape Canaveral on Sept. 8, 2016 aboard a ULA Atlas V rocket. It has since been in orbit around the Sun, and on Sept. 22, 2017 it “borrowed” a bit of Earth’s momentum to put it into the right inclination to meet up with Bennu in August 2018.

The launch of OSIRIS-REx (© Jason Major)

“The encounter with Earth is fundamental to our rendezvous with Bennu,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The total velocity change from Earth’s gravity far exceeds the total fuel load of the OSIRIS-REx propulsion system, so we are really leveraging our Earth flyby to make a massive change to the OSIRIS-REx trajectory, specifically changing the tilt of the orbit to match Bennu.”

During the Earth gravity assist (EGA) scientists used OSIRIS-REx’s MapCam instrument to capture the image of Earth from above the Pacific Ocean (technically an aligned composite of images acquired with MapCam’s W, V, and B channel filters and white-calibrated to Earth’s clouds.) The dark lines at the top are a result of short exposure times…MapCam was specifically designed to image the dark surface of an asteroid, not an enormous, daylit planet! Still, it’s a gorgeous image of our world from space.

Next stop: Bennu!

OSIRIS-REx will spend three years surveying and sampling the surface of Bennu before returning to Earth in September 2023 to drop off its sample within a re-entry capsule.

Source/learn more about OSIRIS-REx here.

UPDATE: The image below shows Earth and the Moon, captured by OSIRIS-REx’s black-and-white NavCam 1 instrument on Sept. 25, 2017 as it was departing. The spacecraft was 735,000 miles away from the Moon and the image shows the distance between the two worlds to scale. (Credit: NASA/Goddard/University of Arizona. Source)