Modelling an encounter between a spacecraft and a cometary meteoroid trail in interplanetary space: The case of the Venus Climate Orbiter and comet 27P/Crommelin

International audienceWe combine modern meteor activity predictors with classical techniques in astrodynamics to formulate a method of predicting encounters between cometary meteoroid trails and spacecraft in interplanetary trajectories. To demonstrate the method, we apply it to the upcoming encounter between the Venus Climate Orbiter spacecraft, due for launch in 2010, and the debris trail of comet 27P/Crommelin which is expected to reach perihelion in mid-2011. We find that a spacecraft utilising a Type II launch window to Venus in 2010 will approach the P/Crommelin dust trail to 0.025 AU on, or around, the 21st November 2010. Adherence to a launch constraint imposed by the current flight plan that limits the declination of the departure asymptote to values shallower than -30° increases this distance to 0.04 AU. A backup, Type-IV launch window for VCO exists in May-June 2011 with arrival at Venus in the Autumn of 2012. In that case, we find that the VCO spacecraft intercepts the trail twice, in late November 2011 and late September 2012, respectively. In the latter case, the expected dust fluence on the spacecraft is 3 × 10 -6 particles with an uncertainty of at least an order of magnitude. In the former case, which we model indirectly since our code can only predict the position of P/Crommelin dust in the vicinity of Venus itself, we find a fluence several times higher than the case in late 2012 but with a higher uncertainty. In both cases, the same declination constraint that was applied for the case of the primary launch window prevents trail interception. Instead, the spacecraft flies by the dust trail at a minimum distance of 0.0175 AU in the latter case and 0.0225 AU in the former case. We advocate studies such as the one presented here as part of mission analysis for future planetary missions. Further direct observations of cometary dust trails will address the main source of model uncertainty