Labels: text | screenshot | machine OCR: MARS AND EARTH: A COMPARATIVE HISTORY THE SEARCH FOR LIFE The problem of Mars (cont.) Volcanic activity on Mars undoubtedly produced an atmosphere composed of carbon dioxide and water vapor. The resulting greenhouse effect probably raised the temperature on the surface above the freezing point. So it is possible that at one time rain fell on the Red Planet, that rivers and even lakes formed. But these phenomena did not last. Since the gravity on Mars is one-third that on Earth, the Red Planet could not hold its atmosphere. All the water vapor eventually escaped, as did the carbon dioxide to a lesser degree (being heavier than water). Some scientists estimate these losses at 1400 tons of water and 130 tons of carbon dioxide. As we have seen, on Earth water vapor became an essential element of the atmosphere; meanwhile, carbon dioxide, which is very water soluble, was dissolved in the oceans. MARS BETAT
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