NASA OSIRIS-REx mission aims to depart Bennu in May

NASA has announced that its OSIRIS-REx mission is scheduled to depart from asteroid Bennu and head back to earth on May 10. OSIRIS-REx, which stands for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, completed its sample collection mission on October 20, 2020. The spacecraft likely exceeded its requirement to collect two ounces of asteroid material.NASA expects OSIRIS-REx to deliver its samples to earth on September 24, 2023. OSIRIS-REx project manager Michael Moreau says that leaving the asteroid's vicinity in May puts the spacecraft in the "sweet spot" when the departure maneuver will consume the least amount of fuel possible. OSIRIS-REx will require over 593 miles per hour of velocity change, marking the spacecraft's largest propulsive maneuver since approaching Bennu in October 2018.

Departing in May will also allow the mission team to plan a final spacecraft flyby of Bennu. This final flyby wasn't part of the original mission. The team is studying the feasibility of a last observation run to learn how contact by the spacecraft altered the asteroid's surface. If the flyby is feasible, it will happen in early April and will observe the sample site from a distance of approximately two miles.

Scientists say the asteroid's surface was considerably disturbed after the sample collection event, and its collector head sinking 1.6 feet into the surface of the asteroid. The spacecraft thrusters also disturbed a substantial amount of surface material on the asteroid during its back-away burn.

The plan is for a single flyby mimicking one of the observation sequences conducted during the mission's Detailed Survey phase in 2019. The spacecraft will image the asteroid for a full rotation to obtain high-resolution images of the northern and southern hemispheres along with the equatorial region of the asteroid. The images will be compared to imagery obtained in 2019.