Scientists should be peering through microscopes, not telescopes, to find life on other planets, says a report by the National Academies' National Research Council issued today. The report urges more research on Earth--both in the lab and in extreme environments such as Yellowstone's boiling hot springs--in order to understand the potential for life based on chemistry that differs drastically from our own. Without such work, the report warns, future searches run the risk of finding life in space but not recognizing it.
According to the report, prepared by a committee of chemists, biologists, geologists, and astronomers, the search for life on other planets has been hampered by Earth-centric assumptions--that life depends on water, for example. Yet the committee suggests that liquids such as ammonia or formamide, a derivative of formic acid, could serve as a solvent for cellular compounds. Indeed, liquid mixtures of water and ammonia have been reported in the interior of Saturn's moon Titan, considered by the committee to be one of the solar system's potentially promising homes to extraterrestrial life.
The report urges scientists to adopt a threefold approach to finding extraterrestrial life: research in the lab, in the field, and in space. Chemists need to create life in the lab with building blocks not used in Earthly organisms. Research already indicates that the four nucleotides that make up our DNA aren't the only possibility for genetics--a 12-letter alphabet makes a perfectly fine genetic code. Field studies of extreme environments, such as the martianlike Atacama Desert in Chile or the Arctic waters, might turn up organisms with a biochemistry vastly different from our own. Combining such lab and fieldwork, space missions should be better equipped to find strange life.
This report is a "tour-de-force" says geoscientist Katherine Freeman of Pennsylvania State University in State College, and "it articulately lays out the risks of focusing on life as we know it." The report encourages NASA to consider some "deep questions," says Steven Benner of the Foundation for Applied Molecular Evolution in Gainesville, Florida. "Why are we here? How did we originate? These are some fundamental questions."