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Rocks and boulders
Rather, it was strewn with large boulders and small rocks, and this created a problem. Because Bennu is now so far from Earth, there is an 18.5 minute delay between here and there. This means that the spacecraft will fly on its own, with automated navigation. Originally, mission planners expected to leave the vehicle in a flat square about 25 meters by 25 meters. But due to the rough surface of the asteroid, there were no such areas.
Image captured on August 11 during the second test of the OSIRIS-REx mission’s sample collection event.
NASA / Goddard / University of Arizona
So now OSIRIS-REx will target a smaller area, only seven meters on a side, adding to the current challenge. The spacecraft will depart its orbit, just over 1 km from Bennu, at 1:50 pm ET on Tuesday (17:50 UTC). It will slowly approach the asteroid and have the ability to abort the “touch and go” maneuver up to a distance of five meters from the asteroid.
Considering the time delay, the spacecraft’s arm will touch Bennu at 6:12 p.m. ET (22:12 UTC), and scientists should know fairly quickly if the maneuver occurred. (NASA will provide live coverage.) However, they won’t have an indication of whether the effort to take a sample was successful until they start getting high-resolution data Tuesday night. Researchers will conduct tests Saturday to try to accurately measure how much asteroid material OSIRIS-REx gathered before determining whether a second attempt is necessary.
To declare the mission a success, the scientists say they need to grab 60 g of asteroid dust. But Heather Enos, a scientist at the University of Arizona, Tucson and OSIRIS-REx deputy principal investigator, said the team hopes for more. “We have the capacity to collect up to two kilograms, and I would love for that capsule to be completely full,” he said. “And I can tell you that I have had some wild dreams.”
After scientists determine that OSIRIS-REx has taken enough pebbles and dust grains from Bennu, it will be time for the spacecraft to return to Earth. A capsule carrying the material is due to land in a Utah desert on September 24, 2023. There may be a few more white knuckles at that time.
