Astrobiology seeks to understand the origin, evolution, distribution, and future of life in the universe and thus to integrate biology with planetary science, astronomy, cosmology, and the other physical sciences. The discipline emerged in the late 20th century, partly in response to the development of space exploration programs in the United States, Russia, and elsewhere. Many astrobiologists are now involved in the search for life on Mars, Europa, Enceladus, and beyond. However, research in astrobiology does not presume the existence of extraterrestrial life, for which there is no compelling evidence; indeed, it includes the study of life on Earth in its astronomical and cosmic context. Moreover, the absence of observed life from all other planetary bodies requires a scientific explanation, and suggests several hypotheses amenable to further observational, theoretical, and experimental investigation under the aegis of astrobiology. Despite the apparent uniqueness of Earth’s biosphere— the “n = 1 problem”—astrobiology is increasingly driven by large quantities of data. Such data have been provided by the robotic exploration of the Solar System, the first observations of extrasolar planets, laboratory experiments into prebiotic chemistry, spectroscopic measurements of organic molecules in extraterrestrial environments, analytical advances in the biogeochemistry and paleobiology of very ancient rocks, surveys of Earth’s microbial diversity and ecology, and experiments to delimit the capacity of organisms to survive and thrive in extreme conditions.
Jiannan Zhao, Yutong Shi, and Long Xiao
Analog study is a convenient and effective way to understand the geomorphic features and geological processes of other planets. The Qaidam Basin, an intramontane basin in the northeastern Tibetan Plateau, northwest China, is a new and unique Mars analog study site. The basin hosts the highest and one of the driest deserts on the Earth, and its environment is characterized as cold, arid, of high altitude, of high UV radiation, and of high soil salinity. A variety of landforms that are comparable to those on the Martian surface have been identified, such as dunes, yardangs, valleys, gullies, lakes, and playas, providing opportunities to study the formation and evolution of similar Martian geomorphic features. Aqueous minerals including chlorides, sulfates, carbonates, and phyllosilicates are concentrated in the saline lakes and playas of the basin. Analog studies on the mineral assemblages of the Qaidam playas and Martian paleolakes and playas will help researchers better understand the hydrological environment and climate of the ancient Mars. The extreme environment of the Qaidam Basin also makes it an ideal site for astrobiological study. Detection of biomarkers and the isolation of microorganisms in the basin could provide clues for the search for life and a habitable environment on Mars. In addition, the accessibility of the Qaidam Basin makes the basin a potential testing ground for instruments and study methods to be used in future Mars missions.