Progress report

“OSIRIS-REx really seeks to answer some of the most fundamental questions that we ask ourselves”

Dante Lauretta

Since OSIRIS-REx arrived at Bennu, it’s spent the best part of a year surveying the asteroid, revealing new mysteries and pinpointing the perfect location to prop itself down to extract a surface sample. On 12 December 2019 the OSIRIS-REx team announced that the site for their sample collection will be a region near the north pole, nicknamed Nightingale. “This is a day I’ve been dreaming of for over a decade,” says Lauretta. “And it’s the culmination of the work of hundreds of people working thousands of hours poring over the data that we’ve returned from the asteroid over the past year.”

Nightingale was chosen ahead of the other sites – Kingfisher, Osprey and Sandpiper – as it showed it has lots of finely grained material, which makes it easy to collect. The region also has a lower albedo, which could be an indication of the presence of organic material.

In other news, astronomers have been trying to work out the mystery of the asteroid ejecting particles into space. When the spacecraft first arrived, these particles could have been easily confused with stars in the background. However, after further investigation it was discovered that the asteroid is emitting material for some unknown reason. Three likely explanations are that it is the result of impacts with meteoroids, thermal stress fracturing or the release of water vapour.

“Among Bennu’s many surprises, the particle ejections sparked our curiosity, and we’ve spent the last several months investigating this mystery,” explains Lauretta. “This is a great opportunity to expand our knowledge of how asteroids behave.”

The team have stated that any of these three explanations are plausible, or it could even be a combination of them. They are also hoping that a sample of this emitted material will find its way into the sampling mechanism of OSIRIS-REx, meaning that there could be an answer waiting for them come 2023.