The main objective of this activity is to study multi-asteroid touring mission concepts using electric solar wind sail technology as the principal propulsion system, to identify the most promising concept and to analyse and develop it to an M-class mission.

The electric solar wind sail (E-sail) propulsion system, because it does not run out of propellant, can enable multi-target missions that can flyby or rendezvous with a larger number of asteroids or other celestial objects. E-sail technology idea was developed in EU FP7 "ESAIL" project (2011-2013).For example, a one kilometre long sample of E-sail tether was manufactured as part of the project.Mass budget estimates of the E-sail indicate that the propulsion system is lightweight enough so that interesting performance is reached for asteroid touring missions, exemplified by a set of calculated flight times to Potentially Hazardous Asteroids. Asteroids are important target for space missions for multiple reasons: scientific (origin and early development of the solar system etc.), Earth impact threat and planetary defence, and in the future possibly also commercial (asteroid mining). Because asteroids are a numerous and diverse target, the efficiency of studying them would be significantly enhanced by an ability to fly E-sail missions that can visit a larger number of asteroids by a single launch.This activity will be formedby several workpackages:1. E-sail design. Analyse requirements posed by the E-sail on the spacecraft platform; recommend E-sail architecture(s) suitable for asteroid missions2. CandidateMissions Evaluation. Analyse possible candidate missions by different classifications: by target bodies (NEO, main belt, Trojans), by mode of encounter (full-speed flyby, slowed-down flyby, close inspection or landing), by included propulsion systems (pure E-sail, E-sail plus conventional). From the large parameter space of possible missions, pick up promising target/technology combinations. The analysed missions should be compatible with typical M-class mission constraints. 3. Mission selection.4.Detailed design of the selected mission and propulsion system development roadmap. Mission objectives, mission analysis, payload, spacecraft systems, spacecraft geometric configuration, moving mechanisms, E-sail (tether rig type and geometry, number and length of tethers, placement of Reel Unit/Remote Unit combinations, placement of auxiliary tether ring, electron gun and high voltage source, power budget, mass budget, significant cabling arrangements, clearance requirement with respect to solar panels etc., restrictions to thruster plumes), conventional propulsion, GNC, power subsystem, command and data handling, telecommunications, thermal design, ground support and operations, analysis of technical risk including preceding E-sail validation mission requirements, cost (cost estimate of the main mission and the required E-sail test and validation mission, decomposed in development, building, launch and operations).