engleski

Implications for global climate change on Mars : intriguing dark streaks and valleys-ocean boundary

While some evidences imply that Mars was for most of its history cold and dry as it is today, other evidences imply that Martian history was much warmer and richer with water. The usual arguments for the first hypothesis is the lack of carbonates in the soil and large amounts of olivine that could survive only in dry conditions. One possible explanation for carbonates is that chemical processes near Martian surface dissolved them. One possible explanation for olivine is that it was exposed to the surface after the Mars was transformed to the present cold and dry state. The other explanation for olivine is that after ejection from volcanoes, in very short time it was covered by large amount of material before it had a chance to react with water, and re-exposed recently again in cold and dry conditions (e.g. Valles Marineris case). On the other hand, not only that some evidences support warm and wet hypothesis, but also that Mars once had rivers, lakes and ocean. Common to all related with the first hypothesis is that climate conditions were the same as today during most of the Martian history. Common to the second hypothesis is that climate significantly changed at some point in time. Accordingly, it has a sense to search for evidences that global climate changed. Recently, it was presented that intriguing dark streaks imply that we are near the end of large climate change on Mars [6thMars #3204]. The first interesting thing regarding them is that there are at least three cases where newly formed dark streak is observed. This proves that process of creation of dark streaks is still going on, meaning that any hypothesis regarding dark streaks has a good chance to be confirmed in some future mission to Mars. One is that formation of dark streaks is related with melting of ground water. This in combination with local distribution of dark streaks, where new one creates where some old one was not before, implies irreversible process where such water accumulated in different climate conditions. Recent analysis additionally shows correlation between valleys-termini and Contact 1 and Contact 2 [35thLPS #1992]. This additionally implies that global climate change happened when proposed ocean was between those two elevations, from warm and wet to cold and dry conditions. Accordingly, conclusion is that while dark-streaks and valleys-termini certainly require some further analysis and additional study by high-resolution color images and perhaps even some rover at the ground, they even now strongly support warm and wet hypothesis. This supports the above mentioned processes on Martian surface, currently not explainable by cold and dry hypothesis.

Mars; climate change

nije evidentirano