CANDIDATE SAMPLE SITES

 

Choosing the Candidate Sample Collection Sites

Each of the four candidate sample sites on Bennu were chosen based on their scores for safety, sampleability, deliverability, and science value. Sites with safe surrounding topography were selected because the spacecraft must be protected as it descends to, touches and collects a sample from the asteroid’s surface. The four sites were also evaluated for the amount of sampleable material they contain. Sites with high sampleability contain material that can be ingested by the spacecraft’s sample mechanism head. To be considered ingestible, rocks and debris must be 2.5 cm or smaller. Deliverability evaluates the relative ease for the spacecraft to be maneuvered in and out of a site. The four sites also have high science value. Science value evaluates the surface properties of each site by measuring the presence of carbon-rich materials, presence of hydrated minerals, alteration of regolith, diversity in material composition and evidence of primitive materials. In December 2019, the OSIRIS-REx team chose sites Nightingale and Osprey as the mission’s primary and backup sample collection sites.