NASA‘s OSIRIS-REx completed its last flyover of Bennu around noon. 6 EDT (4 p.m. MDT) 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 changed the surface of Bennu as it grabbed a sample of the asteroid.
The OSIRIS-REx team added this flyby to document surface changes due to the Touch and Go (TAG) sample collection maneuver on October 20, 2020. “By examining the distribution of the excavated material around the TAG site, we will learn more about the surface nature and subterranean materials along with the mechanical properties of the asteroid, ”said Dr. Dante Lauretta, lead researcher for OSIRIS-REx at the University of Arizona.
During the flight, OSIRIS-REx imaged Bennu for 5.9 hours, covering more than one full rotation of the asteroid. It flew within 3.5 km of the surface of Bennu – the closest it has been since the TAG sampling event.
It takes until at least April 13 for OSIRIS-REx to downlink all data and new images of Bennus’ surface recorded during flyby. It shares the Deep Space Network antennas with other missions like Mars Perseverance, and typically gets 4-6 hours of downlink time per. day. “We collected approx. 4,000 megabytes of data during flyby, ”said Mike Moreau, Deputy Project Manager for OSIRIS-REx at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Bennu is approximately 185 million miles from Earth right now, which means we can only achieve a downlink data rate of 412 kilobits per second, so it will take several days to download all flyby data.”
Once the mission team receives the images and other instrument data, they will investigate how OSIRIS-REx mixed Bennus’ surface. During the touchdown, the spacecraft’s sampling head lowered 48.8 centimeters 1.6 meters into the asteroid’s surface, simultaneously firing a charge of nitrogen gas under pressure. The spacecraft’s thrusters kicked up a large amount of surface material during the recurring combustion – launching rocks and dust in the process.
OSIRIS-REx, with its pristine and precious asteroid cargo remains near Bennu until May 10, when it fires its thrusters and begins its two-year cruise home. The mission delivers the asteroid test to Earth on September 24, 2023.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering and security and mission security to OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security – Regolith Explorer). Dante Lauretta of the University of Arizona, Tucson, is a principal investigator, and the University of Arizona also leads the science team and mission planning and data processing science observation. 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, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the Agency’s Directorate of Science Mission in Washington.