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Project Progress

The focus of the work has been on examining aspects of the martian environment that are relevant to Mars as a possible habitat for prebiotic or biotic activity. This work has examined the modern and the ancient martian environments.

In terms of modern Mars, it is clear that the current environment is not conducive to the preservation of organic matter at the surface as a result of the presence of an oxidant and the high ultraviolet flux. Therefore, if such organic materials existed in the past, they would only be preserved in the subsurface or in material recently brought to the surface. Finding recently exposed material is therefore of high importance. There are two mechanisms to expose material from depth at the surface: impact cratering and landslides.

We have examined cratering rate to estimate the number of craters and the depth of material excavation as a function of time. For example, the estimated number of 1 km craters, which would expose material from depths of as much as 150 m, that are <100,000 years old ranges from about 10-30, depending upon the flux model chosen. These estimates suggest that finding fresh craters would be an important mission planning priority.

We are also examining landslides within Valles Marineris to determine whether the landslide process continues and new wall exposures are continually formed or whether the landslide formation occurred only at a single point in time. TES data are also being examined to determine the composition of the material exposed in the walls of Valles Marineris and the layered deposits of the interior.

Volcanic terrane provide environments on Earth for a variety of thermophilic organisms. Such terranes on Mars might also be suitable habitats. Early in martian history when the impact flux was high and planetary scale sterilization events were occurring, the subsurface would have represented an protected environment. The margins of the Hellas Basin, in the southern hemisphere of Mars, are areas of volcanism and large-scale fluvial processes. The spatial association of heat and water suggest that subsurface hydrothermal systems would have been established and given the scale of the basin and the volcanism, would have been long lived. These environments might have been locations for the development and sustenance of thermophilic organisms. Modern areas of volcanic and fluvial activity include the Cerberus Plains which had large-scale flood basalt eruptions and which are very young (106 million years). The Cerberus Plains could be an area where thermophilic organism could have found a modern niche.

Examination of the layered deposits of the north and south pole using MOC images is being done to determine if the age of the material can be better constrained. Using MOC images, very small diameter craters can be observed. Since these are more abundant than large diameter craters, age variations might be reflected in their spatial variations. Relatively few small diameter craters are observed which is consistent with the layered material being very young.

We continue to examine aspects of the valley networks and erosion characteristics of Mars using MOC and MOLA data. There is a significant discrepancy with respect to the development of the channels and the absence of fine scale surface features indicative of surface flow.