NASA spacecraft swoops down low over asteroid Bennu to eye sampling site

The Osprey backup sample collection site on asteroid Bennu.  (Image credit: NASA/Goddard/University of Arizona)

NASA's OSIRIS-REx spacecraft has taken its closest look yet at a potential sample site on asteroid Bennu.

The probe has been orbiting the asteroid since 2018 and has been preparing to collect a chunk of asteroid rock, which it will bring back to Earth in 2023. OSIRIS-REx is set to take the sample from the site named Nightingale on Oct. 20, 2020, but on May 26 the spacecraft took a dive toward Osprey, the backup sample collection site for the mission. OSIRIS-REx dropped down to just 820 feet (250 meters) above the site, which is the closest the spacecraft has been to Osprey. 

During the operation, the probe took 347 images from PolyCam, one of three cameras on the craft, which were stitched together into a mosaic to show the full site. In the mosaic picture, you can see Osprey located in the crater at the bottom of the image, right above the dark spot in the middle of the crater. 

Video: OSIRIS-REx gets really close to asteroid Bennu in rehearsal
How NASA's asteroid sample return mission will work (infographic)

The purpose of this swooping maneuver was to provide high-resolution images that the OSIRIS-REx team could use to identify the best areas within Osprey for the spacecraft to take a sample should the procedure at Nightingale not work. Wherever the mission's sample comes from on Bennu the spacecraft will use its robotic arm known as TAGSAM (which stands for the Touch-and-Go Sample Acquisition Mechanism). TAGSAM is made up of an 11-foot (3.4-meter) arm with three joints, a sampler head and pressurized nitrogen gas. 

To sample Bennu, the spacecraft will descend toward the surface, unfold its arm, and briefly touch the sampler head to the asteroid's surface. The mechanism will release the nitrogen gas, which will rustle material on the asteroid's surface into the sampler head. Lastly, the spacecraft will photograph the sampler head to make sure that it collected enough material. (Scientists are aiming for at least 2.1 ounces, or 60 grams.) 

By studying an asteroid like Bennu up close and bringing a piece home, scientists can better understand the early solar system, as such asteroids are remnants from this early cosmic time. In fact, some of the mineral fragments inside of the asteroid could be older than the solar system itself, according to NASA. This particular asteroid is not only especially old, but it's uniquely well-preserved so it could be an incredible resource for studying the formation of our solar system or even the origin of life. 

Email Chelsea Gohd at or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

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Chelsea Gohd
Senior Writer

Chelsea “Foxanne” Gohd joined in 2018 and is now a Senior Writer, writing about everything from climate change to planetary science and human spaceflight in both articles and on-camera in videos. With a degree in Public Health and biological sciences, Chelsea has written and worked for institutions including the American Museum of Natural History, Scientific American, Discover Magazine Blog, Astronomy Magazine and Live Science. When not writing, editing or filming something space-y, Chelsea "Foxanne" Gohd is writing music and performing as Foxanne, even launching a song to space in 2021 with Inspiration4. You can follow her on Twitter @chelsea_gohd and @foxannemusic.