Skip to main content
SearchLoginLogin or Signup

The Didymos and Dimorphos global boulder properties and SFD: A comparison with all previously visited NEAs

Presentation #510.06 in the session Asteroids: Planetary Defense (Oral Presentation)

Published onOct 23, 2023
The Didymos and Dimorphos global boulder properties and SFD: A comparison with all previously visited NEAs

On 26 September 2022, the Double Asteroid Redirection Test (DART) spacecraft impacted the surface of Dimorphos, the ~150 m satellite of the binary near-Earth asteroid (65803) Didymos (~730 m diameter). Boulders on small asteroids represent fragments of their parent-body disruptions followed by evolutionary processes (cratering, thermal breakdown, size-sorting, and migration of granular materials). Hence, the observed morphological properties and size-frequency distribution (SFD) of boulders are powerful tools for understanding formation and evolution processes.

During the last minutes of DART, the DRACO scientific camera obtained multiple images of Didymos and Dimorphos with pixel scales ranging from a few meters (on parts of Didymos’ surface) to centimeters (for Dimorphos impact site). To identify and manually count all boulders located in the illuminated areas of both asteroids we use 1) four DRACO images, with a Didymos spatial scale ranging from 4.90 to 3.26 m, and 2) two DRACO images with a spatial scale on Dimorphos ranging from 0.26 to 0.20 m. For the Didymos case, all boulders larger than 10-15 m can be detected, while for Dimorphos all features larger than 0.6-0.8 m can be identified.

Using the Small Body Mapping Tool (SBMT) we directly project the DRACO images onto the Didymos and Dimorphos shape models and count boulders as ellipses. We identify 169 boulders on Didymos and 4734 on Dimorphos. For each boulder SBMT provides the latitude, longitude, axial ratio and orientation, and given the gravity model, the slope, acceleration and potential.

We use the method of Clauset et al. (2009) to evaluate whether a power-law fits the resulting boulder SFD. All the obtained global boulder properties, including the derived SFD, will be presented in the context of previously visited asteroids Eros, Itokawa, Toutatis, Ryugu and Bennu.

Acknowledgments: This research was supported by the Italian Space Agency within the LICIACube project (ASI-INAF agreement AC n. 2019-31-HH.0, & n. 2022-8-HH.0) and the DART mission, NASA Contract No. NNN06AA01C to JHU/APL.

No comments here