如题
The iron rust responsible for the reds and oranges on much of the martian surface is believed to have largely formed early in the history of the planet when its atmosphere may have been different and water in the air was more abundant. In the last billion years or so, the martian atmosphere has been cold and dry. Under these conditions UV radiation bombardment causes a thin top layer in the soil and rock enriched in the oxygen anion ("superoxide", an oxidant) which is capable of further release of iron from mineral by oxidation. However, this is a much slower process and probably doesn't account for most of the iron coloration. One consequence of superoxides is to create an environment that is anathema (destructive) to bacteria and other microbes. This would mean that life right at the surface cannot tolerate these conditions and, if present today, must dwell 10 centimeters or more below the topmost soil layers (life possibilities on Mars is discussed on page 19-13).
Mars was the first extraterrestrial planet mapped in some detail, solely from telescope observations. Thus, in 1881, Giovanni Schiaparelli published the map below, in which many of the features he named are still known as such in today's nomenclature. Although these names are illegible in the figure below, we reproduce this map for its historical importance:
The iron rust responsible for the reds and oranges on much of the martian surface is believed to have largely formed early in the history of the planet when its atmosphere may have been different and water in the air was more abundant. In the last billion years or so, the martian atmosphere has been cold and dry. Under these conditions UV radiation bombardment causes a thin top layer in the soil and rock enriched in the oxygen anion ("superoxide", an oxidant) which is capable of further release of iron from mineral by oxidation. However, this is a much slower process and probably doesn't account for most of the iron coloration. One consequence of superoxides is to create an environment that is anathema (destructive) to bacteria and other microbes. This would mean that life right at the surface cannot tolerate these conditions and, if present today, must dwell 10 centimeters or more below the topmost soil layers (life possibilities on Mars is discussed on page 19-13).
Mars was the first extraterrestrial planet mapped in some detail, solely from telescope observations. Thus, in 1881, Giovanni Schiaparelli published the map below, in which many of the features he named are still known as such in today's nomenclature. Although these names are illegible in the figure below, we reproduce this map for its historical importance: