ten long-term science goals
"origin of life on earth"
Understand how life arose on the Earth.
Terrestrial life is the only form of life that we know, and it appears to have arisen from a common ancestor. How and where did this remarkable event occur? The question can be approached using historical, observational, and experimental investigations to understand the origin of life on our planet. We can describe the conditions of Earth when life began, use phylogenetic information to study our earliest ancestors, and also assess the possibility that life formed elsewhere and subsequently migrated to Earth.
"organization of matter into life"
Determine the general principles governing the organization of matter into living systems.
To understand the full potential of life in the universe we must establish the general physical and chemical principles of life. We ask if terrestrial biochemistry and molecular biology are the only such phenomena that can support life? Having only one example, we do not know which properties of life are general and necessary, and which are the result of specific circumstances or historical accident. We seek these answers by pursuing laboratory experimental approaches and computational theoretical approaches.
"evolution of life"
Explore how life evolves on the molecular, organism, and ecosystem levels.
Life is a dynamic process of changes in energy and composition that occurs at all levels of assemblage, from the individual molecules to ecosystem interactions. Modern genetic analysis, using novel laboratory and computational methods, allows new insights into the diversity of life and evolution at all levels. Complementary to such studies are investigations of the evolution of ecosystems consisting of many interdependent species, especially microbial communities.
"evolution of the ecosystem"
Determine how the terrestrial biosphere has co-evolved with the Earth.
Just as life evolves in response to changing environments, changing ecosystems alter the environment of Earth. Astrobiologists seek to understand the diversity and distribution of our ancient ancestors by developing technology to read the record of life as captured in biomolecules and in rocks (fossils), to identify specific chemical interactions between the living components of the Earth (its biosphere) and other planetary subsystems, and to trace the history of Earth's changing environment in response to external driving forces and to biological modifications.
Establish limits for life in environments that provide analogues for conditions on other worlds.
Life is found on the Earth anywhere liquid water is present, including such extreme environments as the interior of nuclear reactors, ice-covered Antarctic lakes, suboceanic hydrothermal vents, and deep subsurface rocks. To understand the possible environments for life on other worlds, we must investigate the full range of habitable environments on our own planet, not only for what they can tell us about the adaptability of life, but also as analogues for conditions on other bodies in our solar system, such as Mars or Europa.
Determine what makes a planet habitable and how common these worlds are in the universe.
Where should we look for extraterrestrial life? Based on our only example (life on Earth), liquid water is a requirement. We must therefore determine what sorts of planets are likely to have liquid water and how common they might be. Studying the process of planet formation and surveying a representative sample of planetary systems will determine what planets are present and how they are distributed, essential knowledge for judging the frequency of habitable planets.
"signatures of life"
Determine how to recognize the signature of life on other worlds.
Astrobiologists need to learn to recognize extraterrestrial biospheres and to detect the signatures of extraterrestrial life. Within our own solar system we must learn to recognize structural fossils or chemical traces of extinct life that may be found in extraterrestrial rocks or other samples (such as Martian meteorite ALH84001). To understand remotely sensed information from planets circling other stars, we should develop a catalog of possible spectral signatures of life.
"life in the solar system"
Determine whether there is (or once was) life elsewhere in our solar system, particularly on Mars and Europa.
Exciting data have presented us with the possibility that at least two other worlds in our solar system have (or have had) liquid water present. On Mars, there is evidence for stable flowing water early in that planet's history. Both in situ investigations and the analysis of returned samples will be necessary to understand Mars' historical climates and its potential for life. Because their surfaces are inhospitable, exploration of the subsurface probably offers the only credible opportunity to find extant life on either Mars or Europa.
Determine how ecosystems respond to environmental change on time-scales relevant to human life on Earth.
Research at the level of the whole biosphere is needed to examine the habitability of our planet over time in the face of both natural and human-induced environmental changes. To help assure the continuing health of this planet and to understand the potential long-term habitability for other planets we need to assess the role of rapid changes in the environment and develop our knowledge base to enable predictive models of environment-ecosystem interaction.
"expanding beyond earth"
Understand the response of terrestrial life to conditions in space or on other planets.
All terrestrial life has developed in a one-gravity field, protected by the Earth's atmosphere and magnetic field. What happens when terrestrial life is moved off its home planet and into space or to the Moon or Mars, where the environment is very different from that of Earth? Can organisms and ecosystems adapt to a completely novel environment and live successfully over multiple generations? Are alternative strategies practical, such as bioengineering organisms for specific environments? The results from attempting to answer such questions will determine whether Earth's life can expand its evolutionary trajectory beyond its place of origin.