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Uploaded on Jan 2, 2012
"After terraforming , Mars would once again lose its capacity to support life. But 100 million years is a long time. In fact, Earth might not be habitable for much longer than that. As the sun continues to brighten, Earth will succumb to a runaway greenhouse effect. The oceans will evaporate, creating Venus- like conditions unsuitable for life. So our second planetary home might last almost as long as our ﬁrst. " Christopher P. McKay , planetary scientist at NASA Ames Research Center, studying planetary atmospheres, astrobiology, and terraforming. http://channel.nationalgeographic.com...