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What Is Astrobiology?

Astrobiology is the study of the origin, evolution, distribution, and future
of life in the universe. Astrobiologists address three fundamental questions:
How does life begin and evolve? Is there life elsewhere in the universe? What
is the future of life on Earth and beyond?

Icy moons in our solar system are some of the places astrobiologists are studying to search for signs of life beyond Earth.

Icy worlds such as Titan, Europa, Enceladus, and others may harbor the greatest volume of habitable space in the solar system. For at least five of these worlds, Europa, Titan, Ganymede, Callisto, and Enceladus, considerable evidence exists to support the conclusion that oceans or seas may lie beneath the icy surfaces The total liquid water reservoir within these worlds may be some 30-40 times the volume of liquid water on Earth.

This vast quantity of liquid water raises two questions: Can life emerge and thrive in such cold, lightless oceans beneath many kilometers of ice? And if so, do the icy shells hold clues to life under the surface?

Habitability, Survivability, Detectability

The Icy Worlds team of investigators is addressing these questions through conducting three science investigations and one technology investigation that respond directly to the goals of NASA's Astrobiology Program Roadmap. The science goals include:

Instrument Development

Ultimately, the presence of life on icy worlds is of little scientific interest if robotic and human explorers cannot discover the inhabitants. The search for life requires instruments and techniques that can detect biosignatures (substances or elements that provide scientific evidence of past or present life) in space. The Icy Worlds team is working to advance this capability by developing a "path to flight" or astrobiology instrumentation that has not yet reached a technology readiness level adequate for flight.

The investigations are comprehensive- each building upon each other based upon previous investigations and the data they have provided over a long period of time. If we are to discover life on another world, then there must be some detectable signature of that life. In order for a detectable biosignature to persist, something of, or from, the original organism must have survived in the surface ice. For that to occur, various processes beneath the surface must have provided for habitable conditions and a means to transport the organism to the surface.

Ice as a Unifying Theme

Because ice is the dominant form of water in the solar system, the icy worlds team of researchers will follow the ice. In the laboratory, analytically and numerically, as well as in the field, the team is investigating the properties and chemistry of ice. From analyzing the scale of microbes in ice to that of convection in ice shells, the team is working to better understand and constrain the many ways in which icy worlds may provide habitable niches, as well as the role of ice in the broad context of astrobiology. The team's work applies to icy regions on Earth and extends to worlds well beyond Pluto.