An ESA study for the search for life on Mars

Similarities in the early histories of Mars and Earth suggest the possibili ty that life may have arisen on Mars as it did on Earth. If this were the c ase, early deterioration of the environment on Mars (loss of surface water, decrease in temperature) may have inhibited further evolution of life. Thu s, life on Mars would probably be similar to the simplest form of life on E arth, the prokaryotes. We present a hypothetical strategy to search for lif e on Mars consisting of (i) identifying a suitable landing site with good e xobiological potential, and (ii) searching for morphological and biogeochem ical signatures of extinct and extant life on the surface, in the regolith subsurface, and within rocks. The platform to be used in this theoretical e xercise is an integrated, multi-user instrument package, distributed betwee n a lander and rover, which will observe and analyse surface and subsurface samples to obtain the following information: 1. environmental data concerning the surface geology and mineralogy, UV rad iation and oxidation processes; 2. macroscopic to microscopic morphological evidence of life; 3. biogeochemistry indicative of the presence of extinct or extant life; 4. niches for extant life. Lastly, the rationale for human exploration of Mars will be addressed. (C) 2000 Elsevier Science Ltd. All rights reserved.