Goddard Science Colloquium by Laurie Leshin (GSFC) on the preliminary (and as yet unpublished) results from Stardust. She explained why comets are interesting - they were formed far enough out in the proto-Solar nebula that they should be unprocessed material which are deflected into the inner system and hence available for study. Sample return offers the benefit that all the heavy equipment can be kept on the ground and instrument development continues after the mission is completed. Stardust successfully collected cometary dust in its aerogel and preliminary examination is underway. The most unexpected result so far is the discovery of a refractory grain which should not be present in the comet if it is unprocessed.
She finished up by describing SCIM, a Mars Scout proposal, for a sample return mission which dips into the Martian atmosphere during the dust storm season to collect particles then returns them to Earth.