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Meteorites may have transferred life between planets in the solar system


Published: 26Oct2000

A team of research scientists from McGill University, the California Institute of Technology and Vanderbilt University suggests that the Martian meteorite ALH84001 was capable of transferring life between Mars and Earth, according to new research reported in the 27 October issue of the international journal Science.

The Martian meteorite ALH84001 is a rare class of ancient meteorite that includes water-altered minerals and organic compounds. ALH84001, which formed in a magma chamber some 4.5 billion years ago and may contain evidence of ancient life on Mars, was discovered in Antarctica in 1987.

Analysis of the meteorite’s magnetic field reported by Benjamin P. Weiss at the California Institute of Technology, Pasadena, California and colleagues suggests that the interior of ALH84001 was never heated above 40oC before its ejection from the surface of Mars nor during entry into the Earth’s atmosphere.

NASA team member Hojatollah Vali, professor in the Departments of Earth & Planetary Sciences and Anatomy & Cell Biology of McGill University, who in 1996 first reported fossilized evidence of ancient life on Mars, says that a temperature of 40oC is not high enough to sterilize most bacteria. Vali further says that the theory of Cosmic Ancestry holds that primitive life must have evolved elsewhere before coming to Earth. Although life on Earth evolved over billions of years, it is apparent that the genetic programs for higher evolution cannot be explained by random mutation and recombination among genes for single-celled organisms. The pattern of magnetization in ALH84001 supports the hypothesis that meteorites could be an interplanetary delivery system capable of transferring life or the components of life between the planets of our solar system and beyond. Furthermore, as Vali contends: "Since billions of tons of Martian rocks have been transferred to Earth over geological time, protecting the Earth’s present biosphere from rock samples collected by a Martian return mission may not be a major concern."

The fusion crust of ALH84001, the surface of the meteorite that melted during high-temperature passage through the Earth’s atmosphere, has been remagnetized by the Earth’s magnetic field. However, a few millimetres toward the interior of the meteorite, the heterogeneous pattern of magnetization is similar to inside the rock. Experiments on the meteorite suggest only low-temperature heating, which implies that ALH84001 was near the surface of Mars and only lightly shocked during its ejection.

The other members of the research team are Joseph L. Kirschvink, and Francis A. Macdonald, California Institute of Technology, Pasadena, California, and Franz J. Baudenbacher, Nick T. Peters and John P. Wikswo, Vanderbilt University, Nashville, Tennessee