UCSC Researcher Greg Rau Awarded Grant to Study Martian Meteorite

August 15, 1997

Author: Robert Irion

Tim Stephens
UCSC Public Information Office

SANTA CRUZ, CA: A four-pound meteorite from Mars, known unromantically as ALH84001, rocked the world last year when researchers claimed it held evidence that life once existed on the Red Planet. Now, the National Science Foundation has awarded $800,000 for seven new projects to test that extraordinary claim in detail.

Among the grantees is Greg Rau, a senior researcher at the UC Santa Cruz Institute of Marine Sciences. Rau will receive $50,000 over the next two years to probe the meteorite’s different forms of carbon, one of life’s basic elements. He will examine whether some of the rock’s organic carbon might have come from Earth, not Mars. If any of the carbon appears Martian in origin, Rau will try to gauge whether it reflects the type of material that microscopic life-forms would churn out.

Rau’s experiments will make use of approaches he has honed during two decades as an expert on the cycling of carbon in the environment. However, his subject--a chunk of another world--is a far cry from the marine plankton and oceanic sediments he’s used to studying.

“It’s a new environment for me, but the techniques are essentially the same,” said Rau, who has worked at the Institute of Marine Sciences since 1985. “This is a rare opportunity and a very important undertaking.”

Rau is based off-campus at the Lawrence Livermore National Laboratory (LLNL), where he conducts much of his research. He also holds an affiliation with the NASA Ames Research Center in Mountain View. His ALH84001 project is part of a larger, separately funded study of the meteorite by a NASA Ames team led by researcher David Blake.

Scientists believe that ALH84001--so named because it surfaced in the Allan Hills region of Antarctica in 1984--landed on Earth about 13,000 years ago after a 16-million-year odyssey through the inner solar system. A large meteor impact probably blasted the rock free of Mars’s gravitational grip. The meteorite is one of 12 that appear to hail from Mars; their minerals are similar to those found in the Martian crust and are unlike those from all other meteorites.

One year ago, a diverse team of chemists and geologists announced several different lines of evidence that, taken together, hinted strongly that bacteria-like microbes once flourished within the crevices of ALH84001. The evidence included electron micrographs of minuscule structures that the researchers identified as putative “microfossils” of life-forms. However, other scientists have argued that chemical processes alone, in the absence of any biological activity, could account for the oddities in ALH84001.

Rau’s role in this detective story will be to measure the meteorite’s carbon isotopes--different weights of carbon atoms that exist in measurable ratios in minerals and organic matter. He and his colleagues at NASA Ames, directed by isotope biogeochemist David Des Marais, will extract carbon from the rock with a combination of acids, heat, and ultraviolet lasers. In particular, Rau will seek to measure the amount of the heaviest carbon isotope--carbon 14--as well as the ratio of two biologically sensitive isotopes, carbon 12 and carbon 13. John Southon, a research scientist at the Center for Accelerator Mass Spectrometry at LLNL, will help Rau with the isotopic analysis.

Because terrestrial carbon carries a distinct carbon-14 signature, the work should reveal what fraction of the carbon in ALH84001 is non-Martian, having infiltrated the rock during its millennia on Earth. Then, Rau and his colleagues plan to determine the isotopic abundances in the uncontaminated carbon from Mars. This will provide clues to the nature of the planet’s chemical processes.

Rau’s investigation, by itself, will not settle the issue of whether biological processes also might have occurred. Rather, it will illuminate how carbon cycles on Mars might differ from those on Earth. Rau hopes the tests will yield a firm estimate of the original isotopic abundances of organic and inorganic carbon in Martian soils. Such an estimate would provide information on how organic matter is synthesized on Mars.

For their entire project, NASA Ames researchers will receive 15 grams of the meteorite--nearly 1 percent of the rock’s 1.9-kilogram mass. About five grams will be archived for future use.

The National Science Foundation (NSF) and NASA run a joint research program for in-depth studies of ALH84001. NASA announced 16 individual grants under this program in June. Recipients of the latest NSF grants include scientists at Caltech, the University of Wisconsin, Washington University, Arizona State University, and the University of Hawaii. The projects range from scans of the meteorite for microbial alterations to analysis of mineral particles that might serve as “biomarkers” of past life. Some researchers will explore analogous features in microorganisms in extreme habitats on Earth, such as hot springs, that could resemble those on an ancient and wetter Mars.

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