In 1960, NASA created the Office of Life Sciences. One function of this office was to award grants for exobiology research. This research included studying life-detection techniques, learning how to prevent forward and back contamination of planetary environments by spacecraft, and studying the origins of life.
After the founding of NASA’s Office of Life Sciences, exobiology continued to grow. Many scientists who were unable to achieve funding through agencies, such as the National Science Foundation (NSF) and the National Institutes of Health (NIH), that required that their work fit into a rigidly defined scientific discipline were successfully courted by NASA and encouraged to apply for exobiology grants.
NASA’s Office of Life Sciences invested a considerable amount of money in the design and development of life-detection instruments. Three of these instruments were chosen to fly aboard the 1976 Viking mission to Mars. The twin Viking landers were designed to land on the Red Planet and search for the presence of life or organic materials on the surface.
The Viking landers touched down on the surface of Mars in July and September 1976. Although the results were eagerly awaited by many on Earth, scientists were disappointed to find that the data from the landers were ambiguous. While one of the instruments did seem to show a positive detection of life,8 the other two life-detection instruments did not.9,10 Moreover, a fourth experiment revealed no sign of organic material in the samples of martian regolith analyzed.11 Scientists later demonstrated that the positive results from the single experiment likely resulted from abiotic processes related to the highly oxidizing nature of the martian surface material.12
In the wake of Viking’s failure to unambiguously detect biological activity or, even, organic compounds in the martian soil, the exobiology program experienced a decrease in political support. The public, which had been so enthusiastic about the possibility of life on other planets, became disillusioned by the negative results of Viking. Not only did the prestige of exobiology suffer, but the entire Mars exploration program also experienced a lull in the two decades following Viking.
Although funding did not reach pre-Viking levels in this era, work in the field continued. The scientific community remained interested in studying the origins of life, and internal NASA advisory committees and independent groups continued scientific planning for future endeavors in this area. Many significant discoveries were also made in this time period. Indeed, NASA’s strategy of actively seeking out interdisciplinary projects that did not readily find a home in other funding agencies was extremely successful and resulted in the funding of many seminal research activities that proved of lasting value. Examples of important research opportunities funded by the Exobiology program include the following: Lynn Margulis’s work on the endosymbiotic origins of eukaryotic cells, Carl Woese’s discovery of the Archaea, Luis Alvarez’s theory of an asteroid as the cause of the Cretaceous-Tertiary mass extinction, the discovery of microfossils of the earliest life on Earth, and James Lovelock’s Gaia hypothesis.13 This does not mean that other agencies made no contributions to the nurturing of what would later be called astrobiology. NSF, for example, was instrumental in funding many important research activities, including the following: Stanley Miller’s work on prebiotic synthesis; the collection of lunar, martian, and other meteorites in Antarctica; and Geoffrey Marcy’s search for exoplanets, i.e., planets around other stars.14
In 1995, astronomers announced the discovery of an extrasolar planet orbiting the star 51 Pegasi. Although this planet orbits very close to its parent star and is far too hot to harbor life as we know it, this unexpected discovery, taken together with the earlier discovery of planets in orbit around a pulsar, generated enthusiasm for the possibility for countless yet-to-be-discovered planetary systems, some of which could have the potential to sustain life. At about the same time, the Hubble Space Telescope obtained spectacular images of disks around young stars, which were interpreted as possible sites for future formation of planets, perhaps including ones with environmental conditions suitable for life.
Much work was also being done at this time on the existence of life in extreme terrestrial environments, such as deep-sea hydrothermal vents. These new “extreme” life forms expanded the limits of what were once considered to be acceptable conditions for life to develop and proliferate. Finally, observations from the Galileo spacecraft suggested that liquid water existed below Europa’s icy surface, raising the tantalizing idea that life could be found elsewhere in the solar system outside the traditional habitable zone.