SATIS: a mission study for a deep-space CubeSat to observe (99942) Apophis, a near-Earth potential hazardous asteroid, before, during, and after the Earth fly-by

The purpose of this paper is to present the SATIS mission, an ambitious 12UXL CubeSat mission designed in the frame of the ESA's planetary defense activities. The overarching SATIS mission objective is to characterize the physical properties of the near-Earth asteroid (99942) Apophis before, during and after the Earth Closest Approach. To demonstrate the feasibility of the proposed mission, an overview over the science objectives, preliminary mission and CONOPS design has been presented, together with the mission and system challenges. In order to intercept and rendezvous the Potential Hazardous Asteroid Apophis before its Earth flyby in April 2029, transfer opportunities to Apophis have been computed resulting in two potential launch windows, a nominal one in Apr/May 2027 and a backup one in Oct/Nov 2027. The computed transfer opportunities are presented and discussed in the present paper. The interplanetary transfer will then culminate in the arrival and start of the proximity operations where most of the science return is gathered. Different orbital strategies for the proximity operations around Apophis are presented and discussed in terms of its suitability to achieve the defined mission requirements and its impact on the system design.