n this interview, Dr. Christopher Romanek discusses his highly cited Mars research. According to our Special Topics analysis of this field, Dr. Romanek’s work ranks at #7, with 16 papers cited a total of 815 times. Four of his papers also appear on our top 20 lists in this topic. In the ISI Essential Science Indicators Web product, Dr. Romanek’s record includes 19 papers cited a total of 870 times to date in the field of Geosciences. Dr. Romanek is an Associate Professor in the Department of Geology at the University of Georgia, as well as an Associate Research Ecologist at the university’s Savannah River Ecology Laboratory.

The papers I have published in this area rely exclusively on observations made from samples of meteorites thought to have come from the surface of Mars, and among those a particular meteorite named ALH84001 stands out. In 1993, David Mittlefehldt was analyzing the HED class of meteorites, and discovered that one sample, named ALH84001, was probably a Martian meteorite. I had the opportunity to study unusual carbonate minerals in this rock not long after this discovery, and it was from those early efforts that my highly cited references originated.

“As biologists use new tools to uncover the intricacies of the living world, earth scientists will be adapting them to clarify the significance of biological remnants in the rock record.”

At first, interest in this work was limited to the meteoritical community, as my first paper in Nature in 1994 focused on predictions related to the source of carbon and temperature(s) of formation for the carbonates. But continued research led to a second publication in Science in 1996 that raised awareness in the scientific community of the breadth of information that can be gleaned from martian meteorites. Based on previous studies of terrestrial carbonates, I hypothesized that evidence of microbial activity may be uncovered in the carbonates from the ALH84001 meteorite. A small group of researchers, including myself, began studying the carbonates in great detail and asking fundamental questions regarding what substantive fossil evidence proves the existence of biological activity in rocks. While a biological origin for carbonates in the ALH84001 meteorite remains a highly controversial topic, the paper in Science galvanized efforts in the earth sciences community to critically evaluate and develop objective criteria to determine biological origins for surficial materials. Knowledge about the origin of life is ultimately held in Earth's oldest sedimentary rocks, or potentially other surficial deposits of our solar system. The charge to the scientific community is to unambiguously determine the origin of these materials when we are fortunate enough to have access to them.