Space Microbiology

Abstract

The vast, cold, and radiation-filled conditions of outer space present an environmental challenge for any form of life. Earth’s biosphere has evolved for more than 3 billion years, shielded by the protective blanket of the atmosphere protecting terrestrial life from the hostile environment of outer space. Within the last 50 years, space technology has provided tools for transporting terrestrial life beyond this protective shield in order to study in situ responses to selected conditions of space (reviewed in reference 244 and, recently, references 26, 38, and 186). From a biological perspective applicable to organisms ranging from humans to microbes, the two most influential physical modifications experienced onboard an orbiting spacecraft are the state of near weightlessness created by the vehicle’s free-fall trajectory and the increased radiation exposure incurred as a consequence of being outside Earth’s protective atmosphere. Other environmental factors, such as space vacuum, thermal extremes, solar UV radiation, and the presence of high-velocity micrometeoroids and orbital debris, are mitigated by spacecraft design in order to provide internal conditions conducive to sustaining life. Alternatively, space technology provides the opportunity to expose microorganisms intentionally to the harsh external environment or selected parameters of it.