Spacecraft Photographs ‘Popping Rocks’ on Asteroid

Mar 29, 2019

A space mission led by the University of Arizona has been orbiting a near-Earth asteroid for the past three months. It’s turned up a few surprises, including plumes of dust and rubble that erupt off the asteroid’s surface into space. KNAU’s Melissa Sevigny reports.

Particles being ejected from the asteroid Bennu.
Credit NASA/Goddard/University of Arizona/Lockheed Martin


The OSIRIS-REx spacecraft has photographed 11 plumes of dust rising from the surface of Bennu. Some of that material disappears into space or is caught in orbit around the asteroid. 

Carl Hergenrother of the University of Arizona says it’s not clear what’s causes the activity. "It’s possible, it could be that there’s a little bit of water trapped on the surface, or within minerals and rocks, and as they heat up during the day you get this Pop Rock effect, when the rock literally just pops."

Boulders on Bennu
Credit NASA/Goddard/University of Arizona/Lockheed Martin

Spacecraft images also revealed millions of big boulders on the surface. Kevin Walsh of the Southwest Research Institute in Colorado says that was a surprise and it will make collecting a sample of the asteroid more challenging. "It means we’re going to have to be a bit more careful! We were always going to be careful but it means we’ll have to rethink the strategy we use to fly and navigate down to the surface."

The goal is to bring a sample back to Earth in the year 2023. Scientists are studying Bennu to learn about origins of the solar system and how to defend Earth against asteroid impacts.