The OSIRIS-REx spacecraft makes a final flyby of the asteroid Bennu on Wednesday.
The spacecraft made history when it touched the asteroid briefly on October 20, 2020 and collected a strong 2-ounce sample of the surface.
The sample, stored inside the spacecraft, will be returned to Earth in 2023.
The OSIRIS-REx mission, formally known as Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, first arrived on the asteroid in December 2018 and has since orbited it.
During Wednesday’s flyby, the spacecraft will get a final close-up of Bennu, capturing images of the asteroid’s surface just 3.3 miles away. The images should reveal the aftermath of the sampling event in October, which was a messy affair.
The asteroid’s surface was altered when the OSIRIS-REx sampling head sank 1.6 meters above the asteroid’s surface. He fired a charge containing nitrogen gas to disturb the surface material and facilitate the collection of samples. The spacecraft’s propellers also threw material into the air as the spacecraft moved away from the asteroid after collecting the sample.
The gravity of the asteroid is weak, so rocks and dust were thrown and scattered throughout the process.
Images captured by the spacecraft on Wednesday will show scientists how far the sampling event altered the asteroid’s surface. The spacecraft will spend nearly six hours imagining Bennu, allowing its cameras to see the asteroid complete a full rotation.
The route of this overflight is familiar to OSIRIS-REx, which did a similar one while looking for a landing site during the 2019 polls. These 2019 images will be used with the new images to create before and after of comparisons.
During the flyby, OSIRIS-REx instruments will collect data, which will allow the mission team to evaluate them after the tools were covered in dust during the collection event. The spacecraft may perform an extensive mission after leaving the Bennu sample on Earth in September 2023, so this assessment may help teams make that determination.
Days after the flyby, all images and data will be returned to the mission teams so they can analyze the changes in Bennu and evaluate the spacecraft’s instruments.
OSIRIS-REx will remain in the area around Bennu until May 10, and will begin a two-year, 200-million-mile journey back to Earth.
“Leaving the surroundings of Bennu in May puts us at the‘ sweet spot ’when the departure maneuver will consume the least amount of fuel aboard the spacecraft,” said Michael Moreau, deputy director of Goddard Space Flight’s OSIRIS-REx project NASA Center in Greenbelt, Maryland, in a statement.
“However, with more than 595 miles per hour (265 meters per second) of gear change, this will be the largest propulsion maneuver performed by OSIRIS-REx since the approach to Bennu in October 2018.”
The asteroid sample could shed more light on the formation of the solar system and how elements such as water may have been delivered to Earth early by the impacts of asteroids.
Once OSIRIS-REx approaches Earth in 2023, it will remove the capsule containing the sample, which will shoot through the Earth’s atmosphere and parachute into the Utah desert.
A team will be ready to retrieve the sample and transfer it to an aircraft hangar that will serve as a temporary clean room. The sample will be moved to laboratories that are currently under construction at the Johnson Space Center in Houston.
“OSIRIS-REx has already provided incredible science,” Lori Glaze, director of planetary science at NASA, said in a statement. “We are very excited that the mission is planning another overflight of the asteroid Bennu to provide new information on how the asteroid responded (the Touch-and-Go Sample Collection event) and to say goodbye properly.”
