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Multidisciplinary efforts by astrobiologists may increase our understanding of the origins of life on this planet and could result in finding biospheres beyond Earth.

Astrobiology, is the study of life in the universe. The field is driven by fundamental questions that have fascinated scientists and lay people for millennia: Where did we come from? Where are we going? Are we alone? Astrobiology is necessarily a multidisciplinary field, drawing from astronomy, genomics, molecular biology, information technology, geology, paleontology, chemistry, physics, astronomy, and planetary science. Through collaborative efforts among these disciplines, scientists hope to understand the origin, evolution, and distribution of life. Astrobiologists start from the assumption that only by dentifying the 'conditions necessary for life to emerge' can scientists know how and where to look for life elsewhere in the universe, especially when habitable environments may be very different from our own home.

Some scientists, notably Jack Cohen and Ian Stewart, reject the term 'astrobiology' and the whole astrobiology programme along with it. For them, talk of 'conditions necessary for life' is both parochial and unimaginative. They dismiss astrobiology as, "the science of Earthlike planets supporting Earthlike life". In place of astrobiology, they speak about 'xenobiology' -- a science that restricts itself less than astrobiology, does not presume to be able to determine the conditions necessary for life and absolutely refuses to discuss 'habitable zones' (regions around stars that are conducive to Earth-type life -- not to hot nor too cold). In general use, the terms are interchangable, but the existence of an emerging coherent field (astrobiology) and a radical opposition to the growing consensus (xenobiology) is significant.

Because scientists have yet to prove the existence of life on other planets, most astrobiology is done on Earth. For example, researchers have been surprised to find life in such extreme environments as incredibly hot volcanic vents in the deep ocean, icy Antarctic lakes, and highly acidic water. These are the kinds of environments that may harbour life elsewhere in the universe, and studying life forms that thrive there opens our eyes to the robustness and adaptability of life. The search for life in the universe continues in biology laboratories too. All life we know about has a similar biochemical basis but it is currently unknown if DNA, etc. is a necessary condition for all life, or just an 'accident' of life on Earth. Attempts to create synthetic life forms will help answer this question. Advances in theoretical biology precipitated by new mathematical approaches are also helping to set the parameters for the search for life beyond Earth.

In our own solar system, scientists have found evidence of water on both Mars and Jupiter's moon Europa. The existence of water is a necessary condition of all life we know, so locations with water may be a good place to start the search for life. In the coming decades, astrobiologists may very well determine whether life exists there or did in the past. Meanwhile, astronomers continue to discover planets outside our solar system, and one of their goals is to find Earth-like planets with chemistry conducive to life as we know it.

The NASA Astrobiology Roadmap outlines seven scientific goals that are expected to be the most fertile ground for exploration in the coming years:

Understand the nature and distribution of habitable environments in the universe
Explore for past or present habitable environments, prebiotic chemistry, and signs of life elsewhere in our solar system
Understand how life originates from cosmic and planetary precursors
Understand how past life on Earth interacted with its changing planetary and solar system environment
Understand the evolutionary mechanisms and environmental limits of life
Understand the principles that will shape the future of life, both on Earth and beyond
Determine how to recognize signatures of life on other worlds and on early Earth

This will be enabled by:

Continued fostering of multidisciplinary science projects
Renewed interest in space exploration, driven by a desire to know if there's life 'out there'
Development of new biological, chemical, and geological tools for analysing samples brought back from space and extreme environments
Development of increasingly advanced telescopes, both terrestrial and space-based
Advances in A-Life that inform theoretical biology
Development of in the laboratory of synthetic micro-organisms
Development of synthetic organisms that use a mechanism other than DNA or RNA to encode information for reproduction

Early indicators include:

1977 discovery of life in hydrothermal vents
Development by James Lovelock of the Gaia Hypothesis from an attempt to determine if there was life on Mars by studying the planet's atmosphere
Discovery of more than 150 exoplanets
Discovery of evidence of liquid water on Europa and possibly Mars
Ongoing development of plans for a manned mission to Mars before midcentury
Founding in 1998 by US NASA of the NASA Astrobiology Institute (NAI), consisting of hundreds of astrobiologists at more than a dozen institutions around the US, from UC Berkeley to Pennsylvania State University to the SETI Institute
Launching of similar large-scale efforts around the world through such NASA partners as the Astrobiology Society of Britain, Australian Centre for Astrobiology, and the Centro de Astrobiologia
Founding of the International Journal of Astrobiology at Cambridge University
Development of A-life (simulated organisms that live in virtual environments)
Application of cellular automata to theoretical biology

What to watch:

New terrestrial planets like Mars and Earth are discovered.

Potential to discover extraterrestial life
Better understanding of the origins of life on Earth, past extinctions, and the possible future of life on this planet
Better understanding of the impact of space environments on human physiology and our own possible future in space
Potential for medical applications of astrobiology tools such as lab-on-a-chip and other bio-assays