Astrobiology

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Astrobiology

Astrobiology is an area of life science that investigates the origin of life , how the biological components interact to create environment, what makes planets habitable, and searches for life on other planets. Astrobiologists are scientists from many areas of science, including biologists (molecular biologists, microbiologists, ecologists, geneticists), chemists, oceanographers, climatologists, archeologists, paleontologists, geologists and astronomers. The foundations of astrobiology were laid in 1920s by a Russian scientist A.I. Oparin, and with his theory of development of organic matter from inorganic components under the conditions resembling early Earth's atmosphere. It took, however, over half a century before studies into evolution of life on Earth and extraterrestial life became an independent branch of life science. Astrobiology was created thanks to NASA's administrator Dan Goldin in The mid-1990s. Coordination of the global effort in astrobiology rests now with the NASA Astrobiology Institute (NAI), created in 1998 and based at Ames in California, and includes over 700 scientists from numerous research institutes in the U.S. affiliate organizations were also created in Europe and Australia .

Aims of astrobiology

The NAI identified three main goals of astrobiology. Primary among these goals is the investigation of the evolution of life principally on Earth. This is achieved by understanding how organic matter became organized into living organisms, and how life and environment coevolved with Earth. NAI's second aim is to find extraterrestial life by identifying habitable planets. This will require identification of conditions essential for life to develop, and searching for life signatures on planets of the solar system and beyond. The third goal is to determine the future of life on Earth and in outer space . This area is addressed by studying the response of terrestrial organisms to reduced gravity conditions, and investigating how the environmental changes affect life on Earth.

Current research in astrobiology

Studying the Earth history revealed that life appeared on our planet after its surface had adequately cooled down, around 3.8 billion years ago. Fossil evidence indicated that the first organisms were unicellular (one-celled) and anaerobic (non-oxygen requiring). By studying extreme environments such as thermal vents, the freezing waters of the Antarctic, and anoxic marine sediments, scientists are able to determine mechanisms of microbial evolution, and reconstruct the early history of life on Earth.

The evolution of life on Earth is closely linked to extraterrestial intervention in form of asteroids, comets

and meteors. These objects falling onto Earth were likely to bring inorganic and organic compounds used later to create proteins and DNA, the basis of life, as it is known today. Analysis of space dust from our galaxy and beyond revealed presence of ammonia and organic compounds such as glycine, vinyl alcohol , benzene , polycyclic aromatic hydrocarbons , and formaldehyde.

The crushing of large objects onto the Earth's surface not only brought new molecules to Earth, but also often had catastrophic consequences leading to sudden climate changes and mass extinctions (for example, the disappearance of the dinosaurs). Events from Earth's past were described by scientists studying fossils, rocks , and more recently, Greenland's and Antarctic ice sheets.

Signs of life on planets and moons of the solar system are investigated by analyzing meteors that landed on Earth. These, however, could have been potentially contaminated by terrestrial material making it impossible to interpret the results. Therefore, the studies of rocks originating on Mars are much more interesting, provided that samples are kept in isolation. Clues to the existence of extraterrestial life are also provided by studies of the chemistry and geology of the surface of planets and moons. The presence of hydrated salts and formations similar to ice fields of the Antarctic were identified on Jupiter's moons Callisto, Europa, and Ganymeda.

Beside searching for life in and beyond our solar system, astrobiology is involved in studying the response of Earth lifeforms to weightlessness in orbit and possible space travel. Space shuttle missions have investigated the effects of lack of gravity on the physiology of human and animal bodies and their immune system , plant growth in space, and fertilization . Early twenty-first century planned research includes flying worms into space and studying gene expression in their multiple generations to see if weightlessness affects them similarly to vertebrates . So far, the main problems encountered with prolonged stay in space are muscle atrophy (shrinkage), loss of bone mass, and radiation exposure , especially during walks outside the shuttle.

Future of astrobiology

New challenges for astrobiology include developing methods to test the newly discovered extrasolar planets for life signs, which can be quite different from what is now known. Although traveling in space is still limited, it is important that scientists establish ways in which terrestrial organisms can safely live in space for prolonged periods.

Resources

books

Horneck, Gerda, and Christa Baumstark-Khan, eds. Astrobiology: the Quest for the Conditions of Life Berlin: Springer, 2002.

Periodicals

Blumberg, Baruch S., "Astrobiology: an Introduction." Anatomical Record (November 2002):169–170.

Drake, Michael J, and Bruce M. Jakosky, "Narrow Horizons in Astrobiology." Nature (February 2002):733–734.

Organizations

NASA Astrobiology Institute, Ames Research Center, Moffett Field, CA 94035 [cited November 10, 2002]. <http://astrobiology.arc.nasa.gov>.

Other

"The Astrobiology Web. Your Online Guide to the Living Uni verse" [cited November 14, 2002]. <http://www.astrobiology.com>.

Astrobiology Web. "Astrobiology 101:Exploring the Living Universe." Mitchell K. Hobish, and Keith Cowing 1999 [cited November 14, 2002]. <http://www.astrobiology.com/adastra/astrobiology.101.html>.

Agnieszka Lichanska

KEY TERMS

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Anoxic: —Deprived of oxygen
Astrobiology: —The study of living organisms on planets beyond Earth and in space.
Evolution: —in biology, inheritable changes occurring over a time span greater than one generation.
Extraterrestrial: —Beyond Earth

The Gale Encyclopedia of Science