The Rosetta campaign to detect an exosphere at Lutetia

Abstract 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 23  molecules s −1 for water and by ROSINA RTOF to be 25  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.