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Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space.

Martian Meteorite ALH84001 macro-view
Close-up photograph of a small piece of Martian meteorite ALH84001 illustrating rounded carbonate inclusions with orange interiors and blackwhite-black rims.

Martian Meteorite ALH84001
Microscopic view of Martian meteorite ALH84001.

Astrobiology is a cross-cutting theme in all of NASA’s space science endeavors, knitting together research in Astrophysics, Earth Science, and Heliophysics as well as Planetary Science. NASA’s Astrobiology Roadmap, prepared in consultation with the scientific community, outlines multiple pathways for research and exploration and indicates how they might be prioritized and coordinated. The Astrobiology Program also solicits advice from the Space Studies Board of the National Research Council.

NASA’s Astrobiology Program addresses three fundamental questions: How does life begin and evolve? Is there life beyond Earth and, if so, how can we detect it? What is the future of life on Earth and in the universe? In striving to answer these questions and improve understanding of biological, planetary, and cosmic phenomena and relationships among them, experts in astronomy and astrophysics, Earth and planetary sciences, microbiology and evolutionary biology, cosmochemistry, and other relevant disciplines are participating in astrobiology research and helping to advance the enterprise of space exploration.

The Astrobiology Program has four elements: the NASA Astrobiology Institute, Exobiology and Evolutionary Biology, Astrobiology Science and Technology for Exploring Planets, and Astrobiology Science and Technology Instrument Development. NASA established the Astrobiology Program in 1996. However, NASA studies in the field of exobiology – a predecessor to astrobiology – date back to the beginning of the U.S. space program.
NASA funded its first exobiology project in 1959 and established an Exobiology Program in 1960. NASA’s Viking missions to Mars, launched in 1976, included three biology experiments designed to look for possible signs of life. In the 21st century, astrobiology is a focus of a growing number of NASA solar system exploration missions.

Focus Areas for Astrobiology

Inner Solar System - Inner solar system bodies are rocky, unlike the gas and water giant planets of the outer solar system. Rocky planets are thought to have formed from the accretion of dust into “planetesimals,” the planetesimals into proto-planets and finally the proto-planets into planets. Many details of this sequence are still unknown, including the composition of the planetesimals. Equally obscure are the histories of the inner solar system worlds: although Venus, the Earth, and Mars are similar to one another, they have evolved in highly distinct ways. We now know that Mars once had water on its surface, and there are tantalizing hints that Venus might have too. Yet only the Earth is currently known to be habitable. Missions currently in operation, development and planning will greatly increase our knowledge of the forces driving planetary habitability and evolution.

Jupiter's moon EuropaFalse color composite of the Minos Linea region on Jupiter's moon Europa.

Outer Solar System - The giant planets of the outer solar system—Jupiter, Saturn, Uranus, and Neptune—and their rings and moons and the ice dwarfs (e.g., Pluto, Charon, Sedna) beyond them hold many clues to the origin and evolution of our solar system as well as providing exciting opportunities for the search for habitable environments. Moreover, an understanding of the formation and dynamics of the giant planets will aid greatly in understanding the nature of extra-solar planetary systems.

Small Bodies of the Solar System - The small bodies in the solar system include comets, asteroids, the objects in the Kuiper Belt and the Oort cloud, small planetary satellites, Triton, Pluto, Charon, and interplanetary dust. As some of these objects are believed to be minimally altered from their state in the young solar nebula from which the planets formed, overall they may provide a window into the early history of the solar system through which insights about the process of planet formation may be drawn.

Astrobiology in Space Exploration Missions

Astrobiology is a cross-cutting theme in all of NASA’s space science endeavors, knitting together research in astrophysics, earth science, and heliophysics as well as planetary science. NASA’s Astrobiology Roadmap, prepared in consultation with the scientific community, outlines multiple possible pathways for research and exploration. The Astrobiology Program already plays a role in many of NASA’s solar system exploration initiatives, and astrobiology is a primary focus of a growing number of upcoming exploration missions.

For example, Phoenix Mars polar-lander mission, launched in August 2007, is designed to conduct in-situ sampling and analysis of Martian surface and subsurface soil and ice. The science objectives of the Phoenix Mars mission are to study the history of water on Mars in all of its phases, search for evidence of habitable zones on Mars and assess the potential for life in the ice-soil boundary of the Martian arctic region. A primary goal of NASA’s Mars Science Laboratory mission planned for launch in 2009 is to determine whether life ever arose on Mars. The Astrobiology Science Laboratory mission proposed as a successor to MSL will be dedicated to astrobiology research on Mars. Astrobiology will play a prominent role in a Mars Sample Return mission as well.

The ASTEP Program sponsors terrestrial field testing of instruments and equipment being developed for MSL and other future planetary missions. The ASTID Program supports the development of instruments for future missions as well. For instance, ASTID funding contributed to the development of the Urey Mars Organic and Oxidant Detector for the European Space Agency’s ExoMars mission. Concepts under consideration for missions to Jupiter’s moon Europa also feature astrobiological investigations.

At the same time that astrobiology plays a key role in many solar system exploration missions, astrobiologists also make extensive use of data produced by other space science projects to study topics such as prebiotic chemistry in interstellar space, the formation of habitable planets, and extraterrestrial environments where prebiotic chemistry or life may have occurred. These projects include the Hubble Space Telescope, Spitzer Space Telescope, and ground-based telescopes around the world at facilities such as the Keck Observatory.

The Astrobiology Program is managed by the Planetary Science Division of the Science Mission Directorate at NASA Headquarters. The Astrobiology Program is closely coordinated with NASA’s Mars Exploration and Planetary Protection Programs.