Modeling the gravitational field of the ore-bearing asteroid by using the CFD-based method

A gravitational field of an ore-bearing asteroid, which usually has an irregular shape and heterogeneous density, is a prerequisite for asteroid exploration (e.g., space mining) missions. Thus, it is a hot topic in planetary science to model the external gravitational field of the ore-bearing asteroid in an efficient and accurate way. In this study, a computational fluid dynamics (CFD)-based method proposed in our previsous studies is investigated further. Firstly, six types of density distribution in asteroid Bennu are simulated as six experimental cases; then the gravitational fields are derived by using the CFD-based method; and finally, the results are compared to the other two solutions derived from the mascons gravity model method (as a benchmark method) and polyhedron gravity model method, respectively. The CFD-based method shows a superior performance in modelling the gravitational field of an irregularly-shaped asteriod with heterogeneous density in terms of both accuracy and efficiency. For example, the CFD-based method only costs 340 s obtaining 1,650,000 gravitational vectors outside the asteroid with a relative error of 1.27 %, compared to the computation time of 14,520 s and the solution accuracy of 3.84 % for the polyhedron gravity model method on the same testing points. The comparison study demonstrates a good potential application of the CFD-based gravitational field modeling method in asteroid exploration missions.