Rosetta Payload Operations During Mars and Earth Swingbys

Abstract

The International Rosetta mission managed by the European Space Agency (ESA) was launched on 2 March 2004 to rendezvous with comet 67P/Churyumov-Gerasimenko (C-G) in May 2014. Upon arrival, the lander carrying 10 experiments will be placed on the comet's surface, and the Rosetta orbiter with 12 experiments will continue to orbit C-G and accompany the comet through perihelion. On its way to C-G, Rosetta performs close flybys at two asteroids, namely 2867 Steins in September 2008 and 21 Lutetia in July 2010. The study of these asteroids forms part of the mission science objectives of Rosetta. In order to reach C-G, Rosetta makes use of three gravity assists at the Earth in March 2005, November 2007 and November 2009, and one Mars swingby in February 2007, resulting in major trajectory modifications. During the swingbys, the experiments use the Earth and its Moon, and the Mars system as targets for calibration, scientific observations and public relations. The experiment observations from Rosetta at Mars were coordinated with Mars Express, and New Horizons which carried out a Jupiter swingby on 28 February 2007. However, payload operations are only possible on a non-interference basis with the critical spacecraft maneuvers. Science operations planning must take into account severe constraints due to e.g. trajectory correction maneuvers, eclipses, occultations, geometry and radiation belts. The experiment observations are linked to the precise time of closest approach (CA) to the planet, which is updated shortly before the swingby. This paper highlights the constraints and corresponding planning aspects which are specific to the Mars and Earth swingbys executed in 2007.