NASA’s OSIRIS-REx Probe Prepares For Final Flyby of Asteroid Bennu Before Returning to Earth


NASA’s OSIRIS-REx spacecraft will get one last close encounter with Bennu on April 7 as it performs a final flyover to capture images of the asteroid’s surface. While performing the flyover, the spacecraft will observe Bennu from a distance of about 3.7 km – the closest it jhas been since the Touch-and-Go Sample Collection event on October 20, 2020, NASA said on Thursday. The OSIRIS-REx team decided to add this last flyover after Bennu’s surface was significantly disturbed by the sample collection event. During touchdown, the spacecraft’s sampling head sunk 48.8 centimetres into the asteroid’s surface and simultaneously fired a pressurised charge of nitrogen gas. The spacecraft’s thrusters also mobilised a substantial amount of surface material during the back-away burn. Because Bennu’s gravity is so weak, these various forces from the spacecraft had a dramatic effect on the sample site — launching many of the region’s rocks and a lot of dust in the process.

This final flyby of Bennu will provide the mission team an opportunity to learn how the spacecraft’s contact with Bennu’s surface altered the sample site and the region surrounding it. After the Bennu flyby, it will take several days for the data from the flyover to be downlinked to Earth. Once the data are downlinked, the team will inspect the images to understand how OSIRIS-REx disturbed the asteroid’s surface material. At this point, the team will also be able to evaluate the performance of the science instruments.

The spacecraft will remain in asteroid Bennu’s vicinity until May 10, when the mission will enter its Return Cruise phase and begin its two-year journey back to Earth. As it approaches Earth, the spacecraft will jettison the Sample Return Capsule (SRC) that contains the rocks and dust collected from Bennu. The SRC will then travel through the Earth’s atmosphere and land under parachutes at the Utah Test and Training Range on September 24, 2023.

Once recovered, the capsule will be transported to the curation facility at the agency’s Johnson Space Center in Houston, where the sample will be removed for distribution to laboratories worldwide, enabling scientists to study the formation of our solar system and Earth as a habitable planet, NASA said.

NASA in January had announced that the return journey of its asteroid-sampling OSIRIS-REx probe is being delayed by two months. OSIRIS-REx spacecraft will finally touch down on earth on September 24, 2023. Michael Moreau, OSIRIS-REx deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland said in a statement that leaving Bennu’s surface in May will give them an apt chance when the departure manoeuvre will take up the least amount of the spacecraft’s onboard fuel. He also mentioned with over 265 meters per second of velocity change, this will be the largest propulsive manoeuvre conducted by OSIRIS-REx since the approach to Bennu in October 2018.

The spacecraft will remain close to asteroid Bennu and enter its Earth Return Cruise phase on May 10, 2021. OSIRIS-REx will jettison the Sample Return Capsule (SRC) as it will come closer to Earth in 2023. The SRC will then travel through the Earth’s atmosphere and land under parachutes at the Utah Test and Training Range. NASA will transport the capsule with asteroid samples to the curation facility at the agency’s Johnson Space Center in Houston and distribute it to laboratories worldwide. The scientists will then study the formation of the solar system and Earth as a habitable planet. Scientists will also investigate how planets formed and how life began, as well as improve the understanding of asteroids that could impact Earth.

NASA’s OSIRIS-Rex will join the two other missions: Japan’s Hayabusa 2 that brought samples from asteroid Ryugu and China’s Chang’e 5 mission that will bring samples from the lunar surface.

Japan’s Hayabusa2 mission returned to earth six years after it was sent on the mission. The spacecraft reached its stationary position above the asteroid Ryugu in June 2018 after travelling 3.2bn km on an orbit around the sun for more than three years. Meanwhile, China’s Chang e 5 mission will be collecting samples from the moon and also test technologies that will be needed for future missions to the Moon as well as Mars.

(With inputs from IANS)


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