NASA's last Bennu flyby will check damage caused by touchdown mission

In late October 2020, NASA performed its touchdown sample collection mission on the asteroid Bennu, a process that involved sinking a sampling head 1.6ft into the surface and then firing pressurized nitrogen gas. The impact combined with the asteroid's weak gravity caused what NASA calls a 'dramatic effect' on the sampling site, and now the space agency is getting a closer look at the damage.

The OSIRIS-REx mission was a success and resulted in the collection of material from the asteroid's surface. NASA explains that its team plans one final flyby around Bennu on April 7 that will observe the sample collection site, giving researchers a look at the damage done by the spacecraft's touchdown.

The observation will involve bringing the spacecraft to around 2.3 miles from Bennu's surface, which will be the closest it has been since the October event. Among other things, the pressurized gas 'mobilized' a bunch of dust and rocks on the surface, particularly in light of the asteroid's low gravity.

"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," NASA explained in its final flyby announcement. The return journey will take two years and is scheduled to start in mid-May.

Images of the collection site will be taken over the duration of 5.9 hours and will cover nearly a full rotation of the asteroid. The high-resolution images will be contrasted with the images captured and sent back before the collection took place, revealing the changes caused by OSIRIS-REx.