The Rosetta campaign to detect an exosphere at Lutetia

On 10th July 2010 the Rosetta spacecraft passed within 3160 km of asteroid 21 Lutetia during which seven instruments attempted to detect an exosphere. A comparison of the sensitivity is made between the different instruments based on a simple spherical out-gassing point source model, which was used to infer that the Lutetia exosphere production rate was determined by MIRO to be <4.3×1023 molecules s−1 for water and by ROSINA RTOF to be <1.7×1025 molecules s−1 for carbon monoxide. Consideration of the flyby geometry and combined instrument operations places further constraints on the exosphere structure and gas production rate. Experience gained during the flyby will prove invaluable for operations planning during Rosetta's approach and orbit of comet 67P/Churyumov–Gerasimenko in 2014.

► Rosetta co-ordinated instrument campaign to detect an exosphere during Lutetia flyby.
► Geometry of flyby described.
► Comparison of instrument sensitivity.
► Upper limits of gas production rate from asteroid 21 Lutetia.
► Discussion of mission scenarios for coma detection at comet.