Wading In Martian Water
Moffett Field CA (SPX) May 03, 2005 The European Space Agency's Mars Express spacecraft has been orbiting Mars for over a year. While the high resolution images of the planet's many craters, volcanoes, and other features get the most notice, the spacecraft's seven instruments have also gathered large amounts of data about the planet's atmosphere, geology, and chemistry. Bernard Foing, ESA Chief Scientist, provides on overview of the most notable discoveries made during Europe's first trip to the Red Planet. In part one of this overview, Foing wades through the evidence for liquid water on Mars. Mars is the little brother of the Earth, with different processes working on different scales. Like Earth, Mars has tectonics, volcanics, erosion, and an atmosphere. We can study the cycle of water on Mars - water can be present as ice, we know it's in the atmosphere, and it has existed there in liquid form. There was evidently liquid water on the surface of Mars in the first billion years of its history. Although Earth and Mars formed from the same materials, the two planets evolved differently. Water in the atmosphere of Mars may have dissipated very early, and so Mars may have turned cold and dry after the first billion years. One indication of this early loss of water comes from how the martian atmosphere interacts with the solar wind. An experiment on Mars Express shows that that this interaction is causing Mars to lose 100 tons of its atmosphere per day. The Earth also loses part of its atmosphere every day to space, but Earth has a magnetic shield. The Earth's magnetosphere prevents particulates from the solar wind from impacting the Earth, and so for this reason, we don't eject as much of our atmosphere. If there had been an extended ocean on Mars 3.5 billion years ago, it might have allowed the planet to maintain a dense atmosphere. The greenhouse on Mars would have kept water stable at the surface.
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