A provocative hypothesis to explain the recent detection of trace amounts of methane (CH4) in the martian atmosphere is based on measurements of underground water samples in South Africa and is presented in the most recent (Volume 6, Number 2) issue of Astrobiology, a peer-reviewed journal published by Mary Ann Liebert, Inc. The paper is available free online at www.liebertpub.com/ast.

T.C. Onstott, D. McGown, J. Kessler, B. Sherwood Lollar, K.K. Lehmann, and S.M. Clifford from Princeton University, the NASA Astrobiology Institute at Indiana University (Bloomington), the University of Toronto (Canada), and the Lunar Planetary Institute in Houston, Texas, in their paper entitled "Martian CH4: Sources, Flux, and Detection" propose that a non-biological (abiogenic) process is responsible for the methane recently detected in the atmosphere of Mars by way of recent satellite and ground based observations. A radiolytic source of hydrogen (H2), when biologically or abiologically reacted with dissolved CO2 in pore water, could form subsurface methane and explain the presence of trace amounts of this gas on Mars today. Radiolytic hydrogen forms when radiation from the decay of naturally occurring radioactive elements strikes water molecules, turning them into hydrogen and oxygen.

"Along with their hypothesis, the authors propose an instrument that could fly on future missions and, with measurements over time, distinguish mechanisms for methane emissions on Mars," says journal Editor-in-Chief, Sherry L. Cady, Ph.D., Associate Professor in the Department of Geology at Portland State University.

The authors propose using a cavity ring-down spectrometer, an instrument capable of guiding a rover to the location of methane emissions and performing experiments that could detect a biotic methane source.

"Measurements of the ratio of methane to helium, hydrogen, and ethane and the isotopic composition of carbon and hydrogen in methane and ethane over diurnal and seasonal changes could help discriminate between non-biological and biological sources for methane," reports Hypothesis Paper Editor Norman H. Sleep, Ph.D., Professor of Geophysics, Stanford University. The author's hypothesis was developed by studying the source of methane in the crust of the Witwatersrand Basin in South Africa, which contains gold-bearing sedimentary rocks that are 2.9 billion years old.

Astrobiology is an authoritative peer-reviewed journal published quarterly in print and online. The Journal provides a forum for scientists seeking to advance our understanding of life's origins, evolution, distribution and destiny in the universe. A complete table of contents and a full text for this issue may be viewed online at www.liebertpub.com/ast.

Mary Ann Liebert, Inc., is a privately held, fully integrated media company known for establishing authoritative peer-reviewed journals in many promising areas of science and biomedical research. Its biotechnology trade magazine, Genetic Engineering News (GEN), was the first in its field and is today the industry's most widely read publication worldwide. A complete list of the firm's 60 journals, books, and newsmagazines is available at www.liebertpub.com.