Characterizing the Effects of Asteroid Structure on Momentum Enhancement from a Kinetic Impactor
Abstract
The NASA Double Asteroid Redirection Test (DART) is the first planetary defense mission to directly test kinetic impactor technology. The mission will launch in 2021, and the DART spacecraft will impact the moon of the 65803 Didymos binary system (Didymos-B) to test kinetic impactor technology. This mission provides a rare opportunity to observe the momentum change of the impacted asteroid. These observations are critical for future planetary defense efforts and will be useful for validating the predictions of impact simulations. Because the target properties and structure of Didymos-B are uncertain, it is important to simulate a variety of potential scenarios. Previous models showed that target structure (e.g., layering or porosity at the micro- and macro-scale) can significantly affect the cratering process and the expected momentum efficiency factor, β. Here, we report on the observed effects of target structure on the resultant deflection. We performed 57 2-dimensional CTH simulations of Didymos-B as a gravitational amalgamation of smaller rocks and regolith (rubble pile). Each simulation included a random rubble configuration such that impact site structure varies across simulations. We use a tabular equation of state ("Sesame") with a p-ɑ porosity model. All asteroid materials are modeled as basalt, while the spacecraft is modeled as a porous aluminum cylinder. The regolith has a microporosity of either 20% or 60%, while the boulders are competent basaltic rocks. We use two different plasticity models within CTH to test material behavior, a pressure-dependent yield surface (the "geo" model) as well as the Brittle Damage with Localized Thermal Softening (BDL) model. We catalogue crater morphology, amount of ejecta, and momentum transfer to the target for each simulation. Approximately 20 simulations are run for each material model set. The material model choice and porosity values also have an effect. For example, when the regolith porosity is set to 60%, we find a range of average β = 2.03-2.23, using the BDL and geo models, respectively. When the regolith porosity is reduced 20%, βmean = 2.30. We present the conclusions of these simulations and discuss their impact on the DART mission.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH54B..02B
- Keywords:
-
- 4301 Atmospheric;
- NATURAL HAZARDS;
- 4314 Mathematical and computer modeling;
- NATURAL HAZARDS;
- 6008 Composition;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES;
- 6022 Impact phenomena;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES