Lunette is a 9 kg gravity-mapping payload, including a 6 kg subsatellite derived from the current CanX Generic Nanosatellite Bus. It is a primary payload on the Student Space Exploration and Technology Initiative (SSETI) European Student Moon Orbiter (ESMO) mission, now completing preliminary design (Phase A) and planned for launch in 2011. The subsatellite will be carried into Lunar orbit aboard SSETI ESMO and deployed to fly in an along-track formation. By performing radio ranging between the subsatellite and the electronics package left behind on the parent, it is possible to map the irregularities in the Lunar gravity.

Forty years after the first spacecraft entered lunar orbit, the gravitational field of the lunar farside remains poorly known, because spacecraft low over the farside cannot be tracked from Earth. Current farside gravity maps are based on indirect information; they are not very precise and their reliability is uncertain. A complete, dependable lunar gravity map would aid both lunar science and lunar mission engineering. The best way to achieve this is with an orbiter plus a subsatellite, doing continuous inter-spacecraft tracking, and recording data when out of touch with Earth.

The primary objective of the Lunette payload is to map the gravity field of the lunar far side to the same accuracy as the maps current available for the near side (10-20 mGal). Six months of formation flying will produce a reliable global gravity map with the desired quality and also provide local measurements better than any current data of selected areas of interest. In the short term, this information is important for planning the orbits and precision landings of future lunar robotic exploration missions. In the long term, this is one of the first steps in surveying the moon's resources when selecting a site for a Lunar base and planning resource utilization.

The subsatellite includes attitude control, imaging, station-keeping and maneuvering propulsion, and a radio transponder for tracking by the electronics package on the parent spacecraft. A block diagram is given below.

The subsatellite and base unit will be built primarily by the Space Flight Laboratory, and the Lunette design is being refined by a team of seven Masters students at UTIAS/SFL. The team is partnered with SP Systems, software architect for the MOST astronomy satellite and primary developer of the Lunette mission concept.

The Lunette science team is led by Dr. Jafar Arkani-Hamed, whose expertise in lunar gravity mapping and geophysics began with Apollo and has continued through over 20 refereed papers on lunar geophysics.

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