NASA’s OSIRIS-REx completes asteroid Bennu’s final tour before its 180,000,000 mile journey back to Earth

This artist’s concept shows the planned flight path of NASA’s OSIRIS-REx spacecraft during its final flight past asteroid Bennu, scheduled for April 7. Credit: ASA / Goddard / University of Arizona

NASA‘s OSIRIS-REx completed its last flyover from Bennu at around 6 a.m. EDT (4 a.m. MDT) on April 7 and is now slowly drifting away from the asteroid; however, the mission team will have to wait a few more days to find out how the spacecraft altered Bennu’s surface when it picked up a sample from the asteroid.

The OSIRIS-REx team added this flyby to document surface changes resulting from the Touch and Go (TAG) sample collection maneuver on October 20, 2020. “By examining the spread of excavated material around the TAG site, we will learn about the nature of the surface and subsurface materials along with the mechanical properties of the asteroid, ”says Dr. Dante Lauretta, principal investigator for OSIRIS-REx at the University of Arizona.

Top view of asteroid Bennu

This image shows a top view of asteroid Bennu, with part of the asteroid’s equatorial rim and the Northern Hemisphere illuminated. It was captured by the PolyCam camera on NASA’s OSIRIS-REx spacecraft on March 4, 2021 from a distance of approximately 186 miles (300 km). The spacecraft’s cameras are aimed directly at Bennu’s North Pole. Two large equatorial craters are visible on the edge of the asteroid (center and center left). The image was acquired during the Post-TAG Operations phase of the mission, as the Bennu spacecraft slowly approached in preparation for a final observational flyby on April 7. Credit: NASA / Goddard / University of Arizona

During the flyby, OSIRIS-REx imaged Bennu for 5.9 hours, covering more than one full rotation of the asteroid. It flew to the surface of Bennu within 3.5 kilometers – the closest since the TAG sample collection event.

It will take at least until April 13 for OSIRIS-REx to download all data and new photos of Bennu’s surface recorded during the flyby. It shares the Deep Space Network’s antennas with other missions such as Mars Perseverance and typically gets 4-6 hours of downlink time per day. “We collected approximately 4,000 megabytes of data during the flyby,” said Mike Moreau, OSIRIS-REx deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Bennu is currently about 185 million miles from Earth, which means we can only achieve a downlink data rate of 412 kilobits per second, so it will take a few days to download all the flyby data.”

OSIRIS-REx Bennu Departure

NASA invites the public to watch OSIRIS-REx take off from Bennu on and NASA TV, May 10, 2021, at 4:00 p.m. EDT.

Once the mission team has received the images and other instrument data, they will study how OSIRIS-REx has scrambled Bennu’s surface. During landing, the spacecraft’s sampling head sank 1.6 feet (48.8 centimeters) into the surface of the asteroid and simultaneously fired a pressurized charge of nitrogen gas. The spacecraft’s thrusters kicked up a large amount of surface material during the back-away combustion, launching rocks and dust.

OSIRIS-REx With its pristine and precious asteroid payload, it will remain near Bennu until May 10, when it will fire its thrusters and begin its two-year cruise home. The mission will bring the asteroid monster to Earth on September 24, 2023.

KinetX Flight Navigator Leilah McCarthy

KinetX Flight Navigator Leilah McCarthy processes navigation images to help target NASA’s OSIRIS-REx latest flyby of near-Earth asteroid Bennu. Credit: KinetX Inc./Coralie Adam

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides general mission management, systems engineering, and security and mission assurance for OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security – Regolith Explorer). Dante Lauretta of the University of Arizona, Tucson, is the lead investigator, and the University of Arizona also leads the mission’s science team and scientific observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers program, operated by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the Scientific Mission Directorate in Washington.