Champollion

Abstract

At the time of the 1996 COSPAR meeting, the US NASA and the French CNES were planning to develop a comet lander as part of the International Rosetta Mission. This lander, named Champollion after the translator of the Rosetta stone, was to be released from the orbiter and landed on Comet P/Wirtanen to perform in situ analyses of the cometary nucleus. The investigations on Champollion focused on objectives that could not be performed from the Rosetta orbiter. Unfortunately, in September 1996, NASA withdrew its support for Champollion, forcing its cancellation. The description provided in this paper is therefore principally of historical interest, but might prove useful to the development of the remaining Rosetta Lander. The instruments on Champollion would have determined the elemental, molecular, mineralogical, and isotopic compositions of material down to depths approaching 1 m below the surface of the nucleus. The physical structure of the nucleus would have been determined through measurements of the near-surface strength, density, texture, porosity, ice phases, and thermal properties. Images were to have been obtained at resolutions ranging from 1 m to 5 μm. Some key features of the lander were its actively controlled descent from the orbiter to the comet nucleus, its 2.5-m spike which served as an anchor, and the high degree of integration of the instruments with the lander structure and subsystems. The lander was powered by primary batteries. The nominal lifetime of the lander on the surface of the comet was 84 hours, during which measurement sequences could be repeated if necessary and subsurface samples could be obtained from at least three different depths.