Mars Life Debate Stays Hot With New Pathfinder Data
(From the July/August 1999 issue of StarDate magazine)
Hot springs may once have bubbled on the surface of Mars, providing comfortable homes for microscopic life, according to a recent analysis of soil from the Mars Pathfinder landing site. But the soil contains no direct evidence of life on Mars -- past or present.
Pathfinder landed on Mars on July 4, 1997, and operated for about three months. Its small Sojourner rover, which ventured a few yards from the landing site, analyzed the chemistry of the Martian rocks and soil. Horton Newsom and Justin Hagerty of the University of New Mexico and Fraser Goff of Los Alamos National Laboratory discovered that the soil chemistry closely resembled that of soil exposed to water heated by molten rock here on Earth. They reported their findings in the Journal of Geophysical Research in April.
Many hot springs on Earth teem with abundant life, and some scientists suggest that such environments would be good places to look for life on Mars. Scientists have not yet discovered active hot springs on Mars, either at or below the surface, but Mars Global Surveyor continues to look for evidence of them from orbit.
Researchers who reported the discovery of possible microscopic fossils in a meteorite from Mars say the rock was exposed to warm water several billion years ago. Although many other scientists who have analyzed the Martian rock found no signs of life, the evidence of past hot springs on Mars may strengthen the case.
Two other spacecraft, Mars Climate Orbiter and Mars Polar Lander, will continue the search for water on the planet. Climate Orbiter is scheduled to enter orbit around Mars in September, while Polar Lander will touch down near the edge of the south polar ice cap in December. The lander will dig into the Martian soil with a small scoop, and will drop two probes that will dig several inches below the surface.
Yet another spacecraft, Hubble Space Telescope, discovered a giant storm system near Mars' north pole. Unlike most Martian storms, which are made of dust, this one consisted of water-ice clouds like those found on Earth. The system measured 1,100 miles (1,765 km) from east to west, and 900 miles (1,440 km) from north to south, and consisted of at least three bands of clouds wrapped around a large "eye."
Hubble imaged the storm on April 27, during the middle of summer in the northern hemisphere of Mars. The storm occurred after the frozen carbon dioxide that makes up most of the north polar ice cap vaporized, leaving only a smaller cap of frozen water. The storm may have been triggered by the large difference in temperature between the ice cap and the rust-colored Martian soil; similar systems in the polar regions on Earth are caused by large temperature differences between the ice cap and the surrounding ocean water.
The Viking orbiters discovered several similar storm systems during the 1970s. All of the storms took place during the northern summer season. -- — Damond Benningfield
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