The Viking Biology Experiment at Forty Years

摘要

Forty years ago the Viking lander alighted on the surface of Mars and forever gave us a sense of the red planet on a human scale. Perhaps the most important component of the Viking mission was the biological experiment, a complex suite of four instruments designed for the direct detection of microbial life. The experiments returned a null result: data was in a gross sense consistent with a finding of life, but in the end more telling about the surface chemistry of Mars, which it was not designed to address. The Viking mission is often construed as the end point of life-origin exobiology within NASA. This paper is an effort to recast Viking as a precursor mission, science done for eventual exploration. It reviews the release of the "blue sky" photograph as analogous to the pressures facing the biology team. It reviews all the instruments designed to return data on Mars, including the biology experiment, and the continuing debate over the results of the life detection experiment.