Presentation #113.04 in the session “Didymos: Throwing DARTs”.
Spacecraft proximity operations around small bodies depend critically on mapping of their gravitational field, for orbiting, landing, surface operations, etc. In addition, it is essential for accurately simulating dynamical phenomena such as impact events and surface material ejection. While the most accurate method of mapping a gravity field is to orbit the body with a spacecraft to measure the acceleration, this method is costly and time consuming. We implement the Venditti and Rocco (2013, 2018) mascon gravity field modeling method as part of our Rebound Ejecta Dynamics (RED) Python package (Larson et al. 2020, Larson & Sarid 2021) and benchmark it using the Didymos binary asteroid system, the target of the Double Asteroid Redirection Test (DART) mission. DART is a particularly useful benchmark since the system’s gravity field will be mapped by observing the DART impact debris in the system. The flexibility of Python allows for functions from RED to be integrated into simulations written in languages other than Python; this versatility makes this shape modeling method more accessible for a wide variety of dynamical simulations, including (but not limited to) modeling ejecta dynamics about a small body. In this presentation, we examine one such implementation, by mapping the distribution of landed ejecta on Dimorphos and Didymos, as an outcome of the DART planned impact. Since the current shape of Dimorphos is unknown, we vary the ellipsoidal axes of Dimorphos to test the effects of the body’s shape on resurfacing of the primary and secondary bodies due to an impact. We also vary the position of the impact event relative to the semi-major and semi-minor axes of Dimorphos. The orientation of the ellipsoidal target body relative to other bodies in the system can create a varying gravity field that, along with the initial velocity distribution and solar radiation, dictates particle trajectories. We produce a local longitude-latitude grid as a provenance map for accumulated particles with each particle’s properties. The particle distributions on the surface may provide a way to characterize the gravity field of the Didymos system prior to DART mapping the system as the impactor approaches.