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Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Bacterial Muck on Mars?
20 March 1997 (All day)
HOUSTON--The authors of the life-on-Mars paper that rocked the world last summer (Science, 16 August 1996, p. 924) say they have found further evidence of past life in the famed meteorite: residue from bacterial secretions. The findings, reported here yesterday at the annual Lunar and Planetary Science Conference, were greeted with skepticism from other scientists at the meeting, suggesting that the debate over martian life isn't likely to end soon.
Geochemist Carlton Allen of Lockheed Martin Engineering and Sciences in Houston announced that his group has identified in meteorite ALH84001 the remains of possible "biofilms"--thin layers of carbon that might have been secreted by some tiny long-gone Martian bacteria. Biofilms are aggregates of bacteria attached to a surface and surrounded by a protective coat of mucus or slime, and they are commonplace on Earth; the best known, perhaps, is dental plaque.
Allen reported that the team--headed by David McKay of NASA's Johnson Space Center in Houston--had further analyzed carbonate globules similar to those that yielded the first putative traces of past life. The researchers lightly etched the globules' surfaces with acid to remove the overlying carbonate. Underneath, they found layers of filmy, flaky material, sometimes with a honeycombed structure, that they surmise are the remains of biofilms. These layers did not occur only around the tiny wormlike features that the team has suggested could be the remnants of ancient bacteria. Rather, said Allen, "we find biofilms all over the place" in the globules.
Experts are taking the preliminary analysis with a grain of salt. McKay and colleagues "have no evidence there are organisms in those features," says David Des Marais, a geochemist at NASA's Ames Research Center in Mountain View, California. The NASA team and others are continuing to analyze the meteorite to gather more clues and to identify possible organic matter.