On July 20, 1976-seven years to the day after Apollo 11 carried human beings to the surface of the Moon-NASA's Viking 1 lander touched down on the rust-colored plains of Chryse Planitia and transmitted the first photograph ever taken from the surface of another planet. Six weeks later, Viking 2 followed, settling onto the rocky terrain of Utopia Planitia nearly halfway around the globe. Together, these two robotic emissaries carried the most sophisticated scientific instruments ever dispatched beyond Earth, including a biology laboratory designed to answer one of humanity's most profound questions: Is there life on Mars?
The Viking Landers: NASA's Pioneering Mars Surface Missions is the definitive scholarly treatment of this landmark program. Drawing on NASA technical reports, peer-reviewed literature, mission documents, and the published accounts of the scientists and engineers who conceived, built, and operated the Viking spacecraft, this monograph reconstructs the full arc of the program-from its origins in the cancelled Voyager Mars project of the 1960s through the final transmission from Viking 1 in November 1982. It examines the political, institutional, and budgetary forces that shaped the program; the extraordinary engineering challenges of designing a spacecraft capable of surviving entry into an alien atmosphere and operating autonomously on an unknown surface; and the scientific investigations that transformed our understanding of the Red Planet.
At the heart of this work is a detailed analysis of the Viking biology experiments-the Labeled Release, Gas Exchange, Pyrolytic Release, and Gas Chromatograph-Mass Spectrometer investigations-and the fierce scientific debate they ignited. When Gilbert Levin's Labeled Release experiment returned results consistent with biological activity at both landing sites, the scientific community was forced to confront the possibility that life had been detected on Mars. Yet Klaus Biemann's GCMS found no organic molecules in the soil, a result so unexpected that it cast doubt on the biological interpretation and led most investigators to conclude that exotic soil chemistry, rather than biology, was responsible. This monograph traces the controversy from its origins in the 1976 data through the perchlorate discoveries of the Phoenix mission in 2008, which suggested that the Viking GCMS may have inadvertently destroyed the very organic molecules it was designed to detect-a finding that has reopened a debate many considered settled.
Beyond the biology experiments, this volume provides comprehensive coverage of the Viking orbiter science program, which produced over 55,000 images and mapped Mars at resolutions that remained unsurpassed for two decades. It examines the meteorological observations that revealed the dynamics of the thin Martian atmosphere, the X-ray fluorescence analyses that determined the elemental composition of the soil, and the physical properties investigations that characterized the mechanical behavior of Martian surface materials for the first time. The orbiter's discoveries-detailed views of Valles Marineris, the Tharsis volcanoes, ancient outflow channels, and the polar layered terrain-established the geological framework within which all subsequent Mars science has been conducted
