Wolfgang Seboldt, Bernd Dachwald
Solar Sails for Near- and Medium Term Scientific Deep Space Missions
In: L.T. DeLuca (Ed.): In-Space Propulsion (Edited Proceedings of the 10th International Workshop on Combustion and Propulsion
, 2003, Lerici, Italy), Politechnico di Milano, Milano, 2005, Paper 31


Providing an innovative and efficient concept for in space propulsion with low-thrust and without any propellant, solar sails offer a wide range of applications for high-energy low-cost missions. They are accelerated in space by reflecting solar photons off large mirroring surfaces, thereby transforming the momentum of the photons into a propulsive force. Solar sails could close a gap in transportation options for highly demanding exploration missions within our solar system and even beyond. The paper briefly reviews the basic principles of solar sails as well as the technical concept and its realization in a ground demonstration experiment performed in 1999 in close cooperation between DLR and ESA. Next possible steps are outlined. They could comprise the demonstration of solar sail deployment and operations in Earth’s orbit and/or the verification of the propulsion concept in the frame of scientific missions. It is expected that the developed design could be extended to sail sizes of about (50-70 m)2 and perhaps even up to (100 m)2 without significant mass penalties. With these areas, the maximum achievable thrust at 1 AU would range between 20 and 90 mN – comparable to some electric thrusters. Such sails with a mass between 70 and 150 kg plus a micro-spacecraft of 70 to 300 kg would have a maximum acceleration in the order of 0.1 – 0.5 mm/s2 at 1 AU, corresponding to a maximum ΔV-capability of about 3 – 15 km/s per year. Two near/medium-term mission examples to a near-Earth asteroid (NEA) are discussed: a rendezvous mission and a sample return mission. Further on a more advanced medium-term mission to the outer solar system is presented.