OSIRIS-REx survived its landing on asteroid Bennu—now we wait to see if it obtained a pattern


At 6:08 p.m. US Eastern Time on Tuesday, NASA’s OSIRIS-REx spacecraft finished a four-and-a-half-hour descent to the surface of asteroid Bennu, 200 million miles from Earth. Once there, it briefly made contact with the ground in an attempt to collect some rocky pebbles and dust before safely flying away. We won’t know if the sample collection was successful until later.

Why do we want a sample? Asteroids like Bennu are some of the oldest objects in the solar system—they are time capsules chock full of the same materials (such as organics and hydrated minerals) that eventually formed into planets like Earth. Studying these asteroids in depth could reveal new insights into how habitable worlds are made. 

But in order to really understand the origin and evolution of these objects, we need to investigate them in laboratories here on Earth. The main goal of OSIRIS-REx has always been to bring back a sample of Bennu so we can take a closer look.

How did it happen? OSIRIS-REx touched down on a 52-foot-long site called Nightingale, within three feet of the landing target. The sample collection was made possible through a “touch-and-go” pogo method in which the spacecraft descended with a large 11-foot-long, one-foot-wide arm extended to the ground, making contact for about six seconds. During that time it fired off nitrogen gas that wafted small rocks and dust into a collection chamber at the head of the arm, with most of the collection occurring in the first three seconds. The head itself seems to have pushed down into the surface and crushed some material, which is expected to have helped the head collect more material. The spacecraft then flew back out to a safe distance away from the asteroid. 


Steven Gregory