OSIRIS-REx

NASA launched OSIRIS-REx on 8 September 2016 to study Bennu, a carbon-rich near-Earth asteroid, and return a sample. The spacecraft arrived at Bennu in December 2018 and surveyed the asteroid to select a sampling site. Bennu is roughly half a kilometre across and has a small-body environment in which close navigation and sampling required detailed mapping.

On 20 October 2020, OSIRIS-REx performed a touch-and-go manoeuvre: it briefly contacted Bennu's surface and used a sampling mechanism to collect regolith—loose rocks and dust. NASA later reported a total returned sample mass of 121.6 grams, more than the mission's 60-gram collection requirement. Direct samples let scientists study material in laboratories on Earth, complementing observations made remotely by spacecraft instruments.

After departing Bennu in May 2021, the spacecraft carried its sample toward Earth. On 24 September 2023, it released the sample return capsule, which landed at the Utah Test and Training Range. NASA's team recovered the capsule and transported the material for curation and scientific study. The spacecraft itself then continued on an extended mission, renamed OSIRIS-APEX, to study asteroid Apophis during its 2029 close Earth encounter.

NASA's initial examination of Bennu material identified abundant carbon and water-bearing clay minerals. Later research can investigate the sample's chemical and mineral composition in more detail and compare it with remote observations of the asteroid. Such findings help scientists examine the early solar system and the distribution of materials relevant to planetary chemistry. Organic compounds are not, by themselves, evidence of life; they can form through non-biological processes.