OSIRIS-REx: Asteroid 1999 RQ36 (Bennu)

[Joseph Buell]

You can explore a 3-D model of Bennu by NASA. https://trek.nasa.gov/bennu

[neufer]

You can explore a 3-D model of Bennu by NASA. https://trek.nasa.gov/bennu

• Every time a "Buell" rings (in another post) he earns his ensign wings.

<<In the United States Navy, the rank of ensign superseded passed midshipman in 1862. Ensign is the junior commissioned officer rank in the United States Navy, the United States Coast Guard, the National Oceanic and Atmospheric Administration Commissioned Officer Corps, and the PHS Commissioned Corps. Prospective Naval Aviators and Naval Flight Officers have a 12 to 18 month flight training track to earn their wings, followed by a six to nine month training track in a Fleet Replacement Squadron before being assigned to fly combat aircraft in a deployable Fleet aviation squadron.>>

[bystander]

OSIRIS-REx Completes Final Tour of Asteroid Bennu
NASA | GSFC | OSIRIS-REx | 2021 Apr 07

This image shows a top-down view of asteroid Bennu, with a portion of the asteroid’s equatorial ridge and northern hemisphere illuminated. It was taken by the PolyCam camera on NASA’s OSIRIS-REx spacecraft on March 4, 2021, from a distance of about 186 miles (300 km). The spacecraft’s cameras are pointed directly at Bennu’s north pole. Two large equatorial craters are visible on the asteroid’s edge (center and center left). The image was obtained during the mission’s Post-TAG Operations phase, as the spacecraft slowly approached Bennu in preparation for a final observational flyby on April 7. Credit: NASA/Goddard/University of Arizona

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NASA’s OSIRIS-REx completed its last flyover of Bennu around 6 a.m. EDT (4 a.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 when it grabbed a sample of the asteroid.

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

During the flyby, OSIRIS-REx imaged Bennu for 5.9 hours, covering more than a full rotation of the asteroid. It flew within 2.1 miles’ (3.5 kilometers) distance to the surface of Bennu – the closest it’s been since the TAG sample collection event.

It will take until at least April 13 for OSIRIS-REx to downlink all of the data and new pictures of Bennu’s surface recorded during the 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 about 4,000 megabytes of data during the flyby,” said Mike Moreau, deputy project manager of 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 of the flyby data.”

Once the mission team receives the images and other instrument data, they will study how OSIRIS-REx jumbled up Bennu’s surface. During touchdown, the spacecraft’s sampling head sunk 1.6 feet (48.8 centimeters) into the asteroid’s surface 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 burn – launching rocks and dust in the process.

OSIRIS-REx, with its pristine and precious asteroid cargo, will remain in the vicinity of Bennu until May 10 when it will fire its thrusters and begin its two-year cruise home. The mission will deliver the asteroid sample to Earth Sept. 24, 2023.

[Forrest White]

The observed increase in the thermal inertia of the soil as it approaches the equator suggests that a certain mechanism of transport and sorting of regolith, depending on the size or composition of particles and boulders, operates in the northern hemisphere of the asteroid.