Magnetic Mars Crystals Show Possible Biological Background
(From the May/June 2001 issue of StarDate magazine)
Ancient Martian bacteria must have produced microscopic magnetic crystals inside a meteorite from Mars, according to a team of scientists that has studied the rock for more than five years. A type of Earth bacteria secretes almost identical crystals, which cannot be produced by any other known chemical or physical process, the researchers say.
NASA and university scientists reported in 1996 that the meteorite, known as ALH 84001, showed several signs of ancient microscopic life, including magnetic crystals and tiny droplets of carbonates like those produced by terrestrial bacteria. Tests by other scientists generally refute the claim, but the original team of researchers has refused to retract any of its claims.
The new study, led by Kathie Thomas-Keprta, an astrobiologist at the Johnson Space Center and a member of the original ALH 84001 research team, examined about 600 of the tiny magnetic crystals. The crystals, called magnetites, were extracted from carbonate droplets that formed while the rock was still on Mars, indicating that the crystals also must have formed on the planet.
About one-quarter of the crystals are identical to magnetites produced by MV-1, a strain of bacteria found on Earth. The magnetites are produced in chains within the bacteria, and they align with Earth’s magnetic field. Biologically produced magnetites are different from those produced by chemical processes, the researchers say.
ALH 84001 is one of the oldest of the 16 known Martian meteorites at 4.5 billion years, the same age as Mars, Earth, and the other planets of the solar system. The meteorite was blasted into space about 16 million years ago when a large asteroid slammed into Mars. Despite the violent collision, additional research shows the interior of the meteorite never heated to more than 105 degrees Fahrenheit. It landed on Earth 13,000 years ago, and was discovered in the Allen Hills of Antarctica in 1984. — Damond Benningfield
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