Partes De Un Resumen

The carbon cycle on early Earth—and on Mars?
Monica M Grady and Ian Wright
1Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
2Departmentof Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UKM


Abstract

One of the goals of the present Martian exploration is to search for evidence of extinct (or evenextant) life.

This could be redefined as a search for carbon.

The carbon cycle (or, more properly, cycles) on Earth is a complex interaction among three reservoirs: the atmosphere; the hydrosphere;and the lithosphere.

Superimposed on this is the biosphere, and its presence influences the fixing and release of carbon in these reservoirs over different time-scales.

The overall carbonbalance is kept at equilibrium on the surface by a combination of tectonic processes (which bury carbon), volcanism (which releases it) and biology (which mediates it).

In contrast to Earth, Marspresently has no active tectonic system; neither does it possess a significant biosphere.

However, these observations might not necessarily have held in the past.

By looking at how Earth's carboncycles have changed with time, as both the Earth's tectonic structure and a more sophisticated biology have evolved, and also by constructing a carbon cycle for Mars based on the carbon chemistry ofMartian meteorites, we investigate whether or not there is evidence for a Martian biosphere.

Keywords: Earth, Mars, carbon, cycle, life

Articles from Philosophical Transactions of the RoyalSociety



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Abstract

One of the goals of the present Martian exploration is to search for evidence of...