Publications by authors named "Ronald-Louis Ballouz"
Images collected during NASA's Double Asteroid Redirection Test (DART) mission provide the first resolved views of the Didymos binary asteroid system. These images reveal that the primary asteroid, Didymos, is flattened and has plausible undulations along its equatorial perimeter. At high elevations, its surface is rough and contains large boulders and craters; at low elevations its surface is smooth and possesses fewer large boulders and craters.
View Article and Find Full Text PDFWhen the OSIRIS-REx spacecraft pressed its sample collection mechanism into the surface of Bennu, it provided a direct test of the poorly understood near-subsurface physical properties of rubble-pile asteroids, which consist of rock fragments at rest in microgravity. Here, we find that the forces measured by the spacecraft are best modeled as a granular bed with near-zero cohesion that is half as dense as the bulk asteroid. The low gravity of a small rubble-pile asteroid such as Bennu effectively weakens its near subsurface by not compressing the upper layers, thereby minimizing the influence of interparticle cohesion on surface geology.
View Article and Find Full Text PDFArticle Synopsis
- - NASA's OSIRIS-REx mission successfully collected a sample from asteroid Bennu in October 2020, with plans to deliver it to Earth in September 2023, despite challenges in finding suitable collection sites due to unexpected surface conditions.
- - A "Sampleability Map" was created to identify and evaluate potential sampling locations on Bennu based on how compatible they were with the spacecraft's sampling mechanism, using a scoring system called "sampleability."
- - The sampleability algorithm assessed surface properties on two levels: globally to understand Bennu's surface as a whole and site-specifically for higher-resolution predictions at targeted collection spots, ultimately aiding in choosing the optimal collection location.