Sources of Organic Molecules

The surface of Mars is dotted with impacts of meteoritic bodies. Moreover, the older are the surfaces, the more numerous are the impacts and more significant are their sizes. Consequently many bodies coming from the interplanetary medium have hit the surface of Mars, particularly at the beginning of its history.36,37,74 Currently, several hundred tons of objects coming from the interplanetary medium fall on the Earth's surface75-78 and also on the surface of Mars. Analyses oftheir molecular composition revealed the presence of organic molecules.79-86 Consequently, it is extremely likely that the surface of Mars had received organic matter coming from the interplanetary medium since the beginning ofits history (Fig. 4.10). It is also possible that endogenous organic syntheses, particularly atmospheric ones, could have taken place.87-90 Many sources could have contributed to the organic matter delivered to the surface of Mars, especially over the first several hundred million years.

Figure 4.7. Infrared image of the Aram Chaos crater. In the center of the crater, a zone of 60 km of diameter containing between 10 to 15% of grey hematite was detected by the instrument TES of the Mars Global Surveyor mission. This crater could have contained a lake in the early beginning of Mars' history. (Source: ref. 61).

Figure 4.7. Infrared image of the Aram Chaos crater. In the center of the crater, a zone of 60 km of diameter containing between 10 to 15% of grey hematite was detected by the instrument TES of the Mars Global Surveyor mission. This crater could have contained a lake in the early beginning of Mars' history. (Source: ref. 61).

Figure 4.8. Infrared image of Mawrth Vallis and identification of clays by OMEGA instrument onboard Mars Express probe. In blue, clay deposit zones. Reprinted by permission from Macmillan Publishers Ltd: Nature 438, 623-627, copyright 2005.

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