NASA confirmed that OSIRIS-REx has completed its last flight over the asteroid Bennu. The flyover was completed around 6:00 am EDT on April 7, leaving the OSIRIS-REx slowly moving away from the asteroid. Mission controllers have a few more days to wait before they are able to find out how the spacecraft changed the surface of the asteroid after its sample-collecting mission.
The OSIRIS-REx team added the additional flyby of the asteroid to document the changes in the surface that resulted from the Touch and Go sample collection maneuver carried out on October 20, 2020. Mission controllers said the survey of the distribution of the excavated material in Around the sample collection site allows to learn more about the nature of the surface and subsoil materials, along with the mechanical properties of the asteroid.
During its final flyby, OSIRIS-REx took images of the asteroid for almost 6 hours, covering more than one complete rotation around Bennu. It flew less than 2.1 miles from the surface, which is the closest the spacecraft has been since the sampling event. It will take a few days before the mission controllers have an idea of the conditions of the landing site, because it will take at least until April 13 for the spacecraft to downlink all data and new photos.
OSIRIS-REx shares the Deep Space Network antennas used to relay data with other NASA missions, including the Mars Perseverance Rover. OSIRIS-REx is typically allowed between four and six hours of downlink per day. So far, the mission’s controllers have received about 4,000 megabytes of data collected during the flyby.
OSIRIS-REx is currently about 185 million miles from Earth, resulting in a slow downlink data rate of 412 kilobits per second. The limited downlink time is available per day and the slow downlink rate means that it will take several days to download all the data. OSIRIS-REx will remain in the vicinity of the asteroid until May 10, when its propellants will fire, and the two-year journey home will begin.