The Martian atmospheric evolution: implications for the planetary water inventory

The study of Mars and its planetary water inventory is particularly interesting because this planet is similar to Earth in many ways. Observations by various spacecraft in the past and more recently by Mars Global Surveyor showed the probable existence, at least in the past, of large quantities of liquid water on the Martian surface or in subsurface layers. Surface features resembling massive outflow channels provide evidence that the Martian crust contained the equivalent of a planet wide reservoir of water several hundred meters deep. Where has this water gone? When water evaporates from the Martian surface, permafrost and subsurface ice reservoirs reach the upper atmosphere where the incoming solar UV radiation can break up the molecules into H, H2 and O. These oxidize the Martian surface soil or are ionized and swept away by the solar wind. Although the evolution of the Martian atmosphere, with regard to water is influenced by non-thermal atmospheric escape processes of heavy constituents to space it is shown that a huge surface sink of atmospheric oxygen - which is photo-chemically incorporated in the Martian surface material - should also exist. The investigation of this oxygen surface sink will give us a better understanding of the Martian atmospheric evolution in addition to the atmospheric loss to space. For getting an idea how much oxygen was incorporated into the Martian soil laboratory experiments and theoretical studies supporting such investigations are planned. The solution to the question and the determination of the total amount of oxygen which is incorporated into the Martian surface is closely connected to another topic which will be researched by Mars Express` landing platform Beagle 2: did the appropriate conditions for the development of life exist at or near the Martian surface at any time in the past and present? The possibility to study theoretically and with laboratory experiments atmospheric-surface weathering and soil-cementation-processes as well as geo-chemically analyzed terrestrial Mars soil analogue material should give a better understanding of the evolution of the Martian atmosphere and the origin of possible primitive life forms on our neighbouring planet.

 

Fecha: 
18/12/2001 - 13:00
Conferenciante: 
Helmut Lammer
Filiación: 
Austrian Academy of Sciences


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