The August 16, 1996, issue of Science contained an article that once again ignited interest in the possibility of life beyond Earth. The authors of the article claimed that they had discovered evidence suggesting that ancient fossilized bacteria were present in the meteorite ALH 84001, a piece of Mars collected in Antarctica in 1984.15 They based this claim on four pieces of evidence: (1) the presence of carbonate globules which had been formed at temperatures favorable for life, (2) the presence of biominerals (magnetites and sulfides) with characteristics nearly identical to those formed by certain bacteria, (3) the presence of indigenous reduced carbon within martian materials, and (4) the presence in the carbonate globules of features similar in morphology to biological structures.
The extraordinary claim of past life from Mars was eagerly reported by the media but received a very skeptical reaction from many researchers. Very little time passed before criticisms of the article were published, sparking a debate over the true nature of the supposed martian “bacteria.” The authors of these opposing articles argued that the putative nanometer-scale microfossils proposed by the discovery team were highly suspect and likely to be of abiotic origin. The formation temperature of the carbonate globules was soon controversial and, in some cases, suggested a value far above the upper limit for life. Some features were very similar to artifacts produced by the application of conductive coatings onto samples during their preparation for study using scanning electron microscopy. In many cases, the supposed biotic features were regarded as too small to support cellular-based metabolisms. It was known that many features resembling morphological and chemical biomarkers are actually formed by abiotic processes. In addition, most of the organic compounds extracted from ALH 84001 showed radiocarbon activity, indicating that they were very young and had been introduced after the meteorite landed on Earth.
The debate concerning the validity of the claims about ALH 84001 played a pivotal role in the development of astrobiology.16 Although the initial suggestions surrounding ALH 84001 have not been sustained, the announcement triggered a political and programmatic reaction out of all proportion to its scientific significance. In response to congressional calls for a space summit—to discuss “the recent evidence that life may have existed on Mars, as well as other significant advances in space science and technology”17—the White House’s Office of Science and Technology Policy and NASA requested that the NRC’s Space Studies Board organize a workshop to discuss the implications of ALH 84001 and other recent advances in the space sciences. The resulting workshop was held on October 28-30, 1996, and concluded that the study of the origins of life, planetary systems, stars, galaxies, and the universe is a powerful organizing theme for NASA’s space science activities. A subsequent briefing of the workshop results to Vice President Gore concluded that the recent discoveries—such as those concerning life in extreme environments, planets around other stars, a subsurface ocean on Europa, and the transfer of material from planet (e.g., Mars) to planet (e.g., Earth) in the form of meteorites—“… are astonishing returns being reaped from years of investment in many scientific disciplines. Now is the time to leverage that investment and to pursue the quest for origins into the 21st Century.”18 On February 6, 1997, President Clinton proposed that funds be appropriated for a major new NASA activity—the Origins Initiative—to focus on studying the origins of life in the context of the formation of planets, stars, and galaxies. This initiative included funding for missions to Mars and Europa, several astrophysical projects, and the initiation of a major program in astrobiology.
The planning for NASA’s Astrobiology program built on several parallel activities that had taken place earlier in the 1990s. As is mentioned above, NASA’s long-standing Exobiology program had achieved much success by concentrating on the funding of activities that did not readily fit within the more rigid disciplinary boundaries favored by other funding agencies. Thus, the Exobiology program naturally gravitated to inter- and cross-disciplinary activities. The concept of a virtual institute focusing on interdisciplinary research related to the origin, evolution, and distribution of life in the universe was pioneered in 1992 within the context of a program to establish several so-called NASA Specialized Centers of Research and Training (NSCORTs). An NSCORT focusing on issues relating to the origins and evolution of life, the so-called NSCORT in Exobiology—initially consisting of five principal investigators (PIs) and 20 students divided among the Salk Institute for Biological Studies, Scripps Institution of Oceanography, Scripps Research Institute, and University of California, San Diego—was established