Word: soiling
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
...three experiments have been extensively tested using terrestrial soil samples and, as a result, it is safe to say that it is extremely unlikely that a false positive result will be obtained...
...Harold Klein, biology team leader of the Viking mission, published about the time that the first U.S. lander went to work on the surface of Mars. Yet last November, after these same life-seeking experiments aboard both the Viking landers had shown apparently positive results in tests of Martian soil, Klein and other NASA scientists seemed unsure. In a Washington press conference summarizing the Viking findings, they announced that the results made it impossible to say that there was or was not life on Mars. That has remained NASA's official position. But unofficially, a handful of scientists support...
...those who hold similar views base their judgment not on new evidence but on an analysis of the biology experiments conducted by the Viking landers. The gas exchange test, based on the fact that terrestrial organisms give off gases as waste products, involved dropping a pinch of Martian soil into a warm, moist test chamber. The aim was to determine whether the sample would give off carbon dioxide, as animals would, or oxygen, as plants do. Scientists were surprised when the sample began releasing oxygen far more rapidly than plants would be expected to do. But they noted that...
More encouraging results came from a second test, in which a sample of Martian soil that had been moistened with a nutrient broth showed a rapid release of carbon dioxide. The result might mean that some kind of microbe was metabolizing the food provided by Viking. But cautious scientists noted that certain peroxides in the soil might also have caused the reaction to occur...
Tests did not find organic, or carbon-based, molecules in the Martian soil. Terrestrial soil is laden with such molecules, which are the remains of living organisms. But scientists agree that this negative finding does not necessarily weaken the case for Martian biology. There may simply have been too few of these molecules in the soil to be detected by the gas chromatograph-mass spectrometer designed to look for them. The picture is complicated by the biology tests run at the second Mars landing site. In the gas exchange test, the soil released substantially less oxygen than the sample...