Small bodies missions and technologies (part 2)

McInnes, Colin and Hughes, Gareth W. and Macdonald, M.; (2006) Small bodies missions and technologies (part 2). In: Proceedings of the 56th International Astronautical Congress. Curran Associates, IAC-05. ISBN 9781604236484

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Abstract

Solar sailing can enable fly-by, rendezvous and sample return missions to high-energy asteroid and cometary targets. Due to the absence of reaction mass, solar sailing can deliver significant effective delta-v to reach high eccentricity and/or high inclination targets which are either difficult or impossible to reach using chemical or even solar electric propulsion. Typically, such missions can be delivered using a small, low cost launch vehicle due to the modest payload required and the use of a low mass solar sail assembly. A range of mission applications will be discussed in some detail, including a sample return mission from a high inclination target body, near Earth asteroid 2001 QP153, selected as a representative high-energy target body to demonstrate the enabling capability of solar sailing for such missions. In addition, fast rendezvous missions to high eccentricity short period comets will be discussed such as Wirtanen and Encke. For sample return mission, the sample can in principle be delivered to the ISS in low Earth orbit rather than aerocaptured. This return mode would allow the structure of highly porous samples to be preserved by avoid the extreme mechanical loads experienced during re-entry. In addition to the effective delivery of payloads to small bodies, solar sails can station-keep at artificial equilibria in their vicinity to provide novel vantage points for imaging and on-orbit science. For example, by hovering at a fixed phase angle relative to the target body, mapping can be conducted by allowing the target body to rotate relative to the static solar sail. Other more exotic possibilities include using the solar sail as a reflector to enhance surface illumination and to illuminate the interior of shaded craters. Finally, the use of solar sail propulsion for near-Earth asteroid hazard mitigation will be discussed. A near-term solar sail will be investigated which can deliver an inert projectile onto a retrograde solar orbit, raising impact speeds to at least 60 km/s. Such high-energy orbits increase the energy liberated during impact by a factor of 40 or more, while reducing the required projectile mass by at least 95\% relative to conventional concepts for kinetic energy impact schemes using prograde orbits. This considerable reduction in projectile mass allows kilometre-sized asteroids to be diverted with current launch vehicles, near-term technologies and at a cost comparable to a modest deep space mission.