Modeling and control techniques for landing on (99942) Apophis: An analysis of a mission scenario

On 13 April 2029, the near-Earth asteroid (99942) Apophis will perform a close flyby within a distance of 32,000 km of Earth’s surface. This event, which is ten times closer than the Moon and closer than many geostationary communication satellites, offers an unprecedented opportunity to study an asteroid in great detail. To leverage this close encounter, a fast sample return mission, APOSSUM, was designed using ESA’s current RAMSES mission as a use case. This paper presents a detailed analysis of the APOSSUM mission scenario, focusing on feasibility. It covers the separation of the APOSSUM probe, its cruise towards Apophis, and the subsequent landing and return phases. Particular emphasis is placed on the landing scenario, with studies of different density models of Apophis and a comparison of control techniques for precision landing. The findings from this mission will significantly advance our understanding of small-body landing maneuvers. • Detailed analysis of a sample return mission to Apophis during its 2029 close Earth flyby. • Comparison of Proportional-Derivative (PD) and Bang-Bang control for precision asteroid landing. • Evaluation of non-uniform density models of Apophis to assess their impact on gravitational dynamics and precision landing strategies. • Gravity modeling via spherical harmonics and tetrahedral mass discretization. • Integration of previous observational data on Apophis for mission feasibility and optimization of landing success. • Comprehensive mission design includes Earth return, targeting Woomera for safe landing.