Water in Impact Shocked Rocks

The fracturing of rocks by the pressure wave generated during impact and the brecciation of target materials creates micro-environments in which water can be preferentially trapped or circulated. Precambrian basement gneiss shocked to > 10 Ga from the Haughton impact structure is found to contain cyanobacterial communities and abundant heterotrophic communities as well 26, 27 . The porosity of this rock is increased substantially by impact-shock such that the surface area of pores greater...

XUVDriven Hydrodynamic Escape

Recent modelling of atmospheric evolution on terrestrial planets has focused on fractionation from primordial source compositions during XUV-driven hydrody-namic escape e.g. 27 . The upper atmospheres of terrestrial planets are mainly controlled by absorption of XUV radiation 28 and additionally by energy deposited in the upper atmospheres by large impacts 29 . By knowing the evolution of the solar XUV radiation with time, one can apply a scaling relation for the estimation of the exosphere...

Polar Hydrology

There are several regions on Earth where mean annual temperatures are well below freezing and yet liquid water persists in these locales. Such polar regions provide an excellent analog to study the hydrological cycle under conditions that have prevailed in the polar desert environment of Mars. In this review we will focus on two areas including Axel Heiberg Island in the Canadian High Arctic and the McMurdo Dry Valleys of Antarctica. In both locations the mean annual air temperatures are...

Morphological Indicators of Ground Ice Existence in the Surface Layers of the Cryolithosphere

Besides theoretical predictions, information about the ground ice distribution on Mars may also be inferred directly from observations of some morphological features on the planet's surface associated with the presence of ground ice. Usually such features have been attributed to rampart craters (craters with fluidized ejecta), lobate debris aprons, terrain softening, polygonal terrains, thermokarst features, askers and moraines, outflow channel and features of volcano-ice interaction 9, 10, 42,...

Evolution of Halophiles

It is clear from the above discussion that halophiles form a phylogenetically diverse group. They occur in all three domains of life. No correlation has been found between an organism's place in the tree of life and its ability to grow at high salt concentrations. Halophiles occur amid non-halophiles in several instances in the tree of life. Adaptation to life at high salt concentrations can be achieved in different ways, as previously discussed. The most commonly occurring strategy involves...

Water in the Solar System

The history of water in the Solar System is still subject to debate and continual revision of ideas. It is, however, useful to have a basic idea of the active history of Solar System water. The ideas presented below are a brief overview of some of the more recent hypotheses that have gained some popularity with workers in the field. H2O and OH- seem likely to have been present in the universe since the first stars completed their life-cycles and released oxygen into the interstellar medium....

Aspects of the Atmospheric Water Cycle

The atmospheric and shallow subsurface water cycle of Mars consists of various components as illustrated in Fig. 8.4. Each of them will be discussed in this section. Atmospheric escape processes discussed in Chap. 2 by Lammer et al. are only relevant on geological time scales, so they are totally negligible in the consideration of the present global water cycle. Fig. 8.4 Schematic diagram showing the different reservoirs of exchangeable water in the atmosphere and shallow subsurface as well as...

Mars

Mars is a cold dry planet bombarded with UV radiation. Overall, it is currently considered inhospitable to life. Yet, Mars is considered the most likely planet, next to Earth, to either harbor life now in protected oases, or to have done so sometime during its past. It is thought that all of the constituents for life are present on the planet, and that the radiation regime would not have precluded the origin and evolution of life 4, 72 . The one factor that would preclude life on Mars at any...

Stability of Ground

The equilibrium of ground ice with the Martian atmosphere or the conditions for its stable existence in the surface layers is determined by the correlation between two fundamental processes sublimation of ground ice and condensation of atmospheric moisture into the surface regolith 25, 28, 63 . The first process dominates on Mars when ground temperatures are above the frost-point temperature (the temperature at which the atmospheric water vapor will begin to condense) corresponding to the...

References

1 Anders E, Owen T (1977) Mars and Earth origin and abundance of volatiles. Science 198 453-465 2 Baker VR, Milton DJ (1974) Erosion by catastrophic floods on Mars and Earth. Icarus 23 27-41 3 Baker VR (1982) The Channels of Mars. Univ. of Texas Press, Austin 4 Banin A, Mancinelli RL (1995) Life on Mars I. The chemical environment. Adv. Space Res. 15(3) 163-170 5 Ben-Amotz A, Grunwald T (1981) Osmoregulation in the halotolerant alga Asteromonas gracilis. Plant Physiol. 67 613-616 6 Bauld J...

Ground Ice in the Martian Regolith

The long-term existence of extremely cold climate on Mars has led to strong global freezing through upper layers of the planet's crust that has resulted in formation of the global permafrost shell - cryolithosphere. In accordance with the modern thermal regime of the Martian surface and the reasonable values of the planet's heat flow, the thickness of the cryolithosphere may approach 1-2 km in the equatorial zone and 5-6 km in the polar regions. In the presence of such a huge scale of...

Microbial Communities

Several components are frequently distinguished among deep-sea vent microbial communities free-living and surface-bound bacteria in the warm and cold areas, invertebrate symbionts, thermophilic (and hyperthermophilic) organisms. 13.2.1 Free Living and Attached Bacteria in Warm and Cold Vent Areas When approaching an active vent side with a manned-submersible, it is very common to observe bacterial mats on the sea bottom that can sometimes reach a thickness of several centimetres. The bacteria...

Where Do Halophiles Live

Lake environments are numerous and diverse ranging from fresh non-saline to hypersaline, from acidic to alkaline, and cold to hot. Lakes comprise a complex and diverse array of ecosystems. Hypersaline lakes regardless of their other environmental attributes serve as habitats for halophiles. Hypersaline lakes fall into two categories thalassohaline and athalassohaline. Thalassohaline lakes are those that originated by evaporation of seawater having an ionic composition reflecting that of...

Properties of Hydrated Minerals That May Be Present on Mars

The hydration properties of minerals play an important role in how water cycles between the surface and atmosphere on Mars as described in Chap. 8 by Tokano. This includes the ability of minerals to adsorb (attract and physically attach) water molecules and how fast they can take up this water. Besides adsorbed water, some minerals need bound (chemically attached) H2O as part of their structure. Other minerals require OH that is usually bound in an octahedral configuration. Most minerals that...

Hydrated Minerals

Minerals are combinations of atoms that form in a specific structure and have common properties such as color, texture, and hardness e.g. 1 . Minerals are sometimes found in pure outcrops, but more frequently occur in rocks as combinations of minerals, where the grains of many minerals neighbor each other and may be intergrown. Hydrated minerals are usually thought to include water or hydroxyl (OH) in their mineral structures and several examples are listen in Table 4.1. However, they can also...

What Are Halophiles

What Are Halophiles

Halophiles are microorganisms that live in hypersaline environments that have salt concentrations ranging from 15 to saturation. All three domains of life, the Archaea, the Bacteria and the Eukarya have halophilic representatives (Fig. 12.1). These organisms are abundant in hypersaline environments forming populations so dense that the red color associated with hypersaline lakes and ponds is due to the pigmentation of the halophilic Archaea and the eukaryote Dunaliella (Fig. 12.2). Although...

List of Contributors

Amerstorfer (Chap. 2) Institute of Geophysics, Astrophysics and Meteorology, University of Graz, Universit tsplatz 5, 8010 Graz, Austria E-mail te_amerstorfer hotmail.com Dale T. Andersen (Chap. 9) Department of Geography, McGill University, 805 Sherbrooke St. W., Montreal, Quebec, Canada H3A 2K6 E-mail dandersen seti.org Janice L. Bishop (Chap. 4) SETI Institute NASA Ames Research Center, MS 239-4, Moffett Field, CA 94035-1000, USA E-mail jbishop mail.arc.nasa.gov Nathalie A. Cabrol...