Martian paleolakes and waterways: Exobiological implications

Abstract

Abstract. The problems of how warm and wet Mars once was and when climate transitions may have occurred are not well understood. Mars may have had an early environment similar to Earth's that was conductive to the ermergence of life. In addition, increasing geologic evidence indicates that water, upon which terrestrial life depends, has been present on Mars throughout its history. This evidence suggests that life could have developed not only on early Mars but also over longer periods of time in longer lasting, more clement local environments. Indications of past or present life most likely would be found in areas where liquid water existed in sufficient quantities to provide for the needs of biological systems. We suggest that paleolakes may have provided such environments. Unlike the case on Earth, this record of the origin and evolution of life has probably not been erased by extensive deformation of the Martian surface. Our work has identified eleven prospective areas where large lacustrine basins may once have existed. These areas are important for future biological, geological, and climatological investigations.

Episodic flood inundations of the northern plains of Mars

“…The presence of large bodies of water during different periods of time on the northern lowlands of Mars have been previously proposed (McGill, 1985;Jöns, 1986;Lucchitta et al, 1986;Parker et al, 1987Parker et al, , 1989Parker et al, , 1993Baker et al, 1991;Scott et al, 1991aScott et al, , 1991bChapman, 1994;Scott and Chapman, 1995;Kargel et al, 1995;Head et al, 1999). For example, Parker et al (1987Parker et al ( , 1989 described seven different boundaries, but only two of them could be approximately traced as complete closures within and on the margins of the northern lowlands.…”

A volcanic origin for the outflow channels of Mars: Key evidence and major implications

“…Sediment loads more typical of terrestrial fluvial systems suggest water volumes up to two to three orders of magnitude greater than these estimates (e.g., Komar, 1980;Harrison and Grimm, 2004;Ghatan et al, 2005;Kleinhans, 2005;Andrews-Hanna and Phillips, 2007), implying equivalent water layers of at least tens of kilometers thickness if water recycling is unrealistically assumed to have not occurred. Because water in the regions of hypothesized aqueous outbursts cannot be assumed to have been recycled with full efficiency, aqueous interpretations of the outflow channels must also account for the existence of significant groundwater volumes never expelled to the surface and therefore never directly involved in outflow channel incision (e.g., Scott et al, 1991;Baker et al, 1992a). Thus, even under the reasonable assumption of the past operation of an active hydrological cycle capable of repeated recharge of hypothesized reservoirs, outflow processes appear to require volumes equivalent to a global layer of at least several kilometers thickness (even assuming high sediment loads of~5 to 10%).…”

The role of Raman spectroscopy as an astrobiological tool in the exploration of Mars

“…There are at least 15 large basins on Mars exceeding 100 000 km 2 in area and 1000 m in depth, of which Elysium is the only depositional basin, although many smaller basins including crater depressions show evidence of sedimentation. 67 The most promising astrobiological environments are palaeolake craters with siliciclastic sediments. There are three palaeolake features of astrobiological interest: 59 (i) strand lines marking former lake levels, i.e.…”