This article is about the scientific discipline. For the journal, see Astrobiology (journal). For the International Journal of Astrobiology see International Journal of Astrobiology.

The DNA structure might not be the only nucleic acid in the universe capable of supporting life. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known A nucleic acid is a Macromolecule composed of chains of monomeric Nucleotides In Biochemistry these Molecules carry Genetic information The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism ^[1]

Astrobiology (from Greek: ἀστρο, astro, "constellation"; βίος, bios, "life"; and λόγος, logos, "knowledge") is the interdisciplinary study of life in the universe, combining aspects of astronomy, biology and geology^[2]. In Academia, Pedagogy, Physical sciences, Earth sciences, Human sciences and Social sciences Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Foundations of modern biology There are five unifying principles Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit It is focused primarily on the study of the origin, distribution and evolution of life. In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic eVolution is the third Album by eLDee, it was due to be released in 2008 Given the influx of new information about planetary systems around other stars, its mandate has expanded beyond the study of exobiology (from Greek: έξω, exo, "outside")^[3][4][5] per se. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth

Some major astrobiological research topics include:^[2][6][7][8] What is life? How did life arise on Earth? What do astrophysical observations tell us about the present and future of life on Earth?^[9] What kind of environments can life tolerate? How can we determine if life exists on other planets? How often can we expect to find complex life? What will life consist of on other planets? Will it be DNA/carbon based or based on something else?^[1] What will it look like?

Overview

It is not known whether life elsewhere in the universe would utilize cell structures like those found on Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is (Chloroplasts (small green objects) within plant cells shown here. Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. ) According to NASA, the color of plant pigments on extrasolar planets may be different from our own. ^[10]

Although astrobiology is an emerging field and still a developing subject, the question of whether life exists elsewhere in the universe is a verifiable hypothesis and thus a valid line of scientific inquiry. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding Astrobiology is a multidisciplinary field utilizing physics, biology, and geology as well as philosophy to speculate about the nature of life on other worlds. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Foundations of modern biology There are five unifying principles Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Philosophy is the study of general problems concerning matters such as existence knowledge truth beauty justice validity mind and language One commentator on the field, planetary scientist David Grinspoon, calls astrobiology a field of natural philosophy, grounding speculation on the unknown in known scientific theory (Grinspoon 2003). Since we have only one example of a planet with life (the earth), most of the work is speculative and based on current understanding of physics, biochemistry, and biology. ^[11][12]

Though once considered outside the mainstream of scientific inquiry, astrobiology has become a formalized field of study. NASA now hosts an Astrobiology Institute. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The NASA Astrobiology Institute (NAI engages in government-funded Exobiologic study of the living universe ^[13] Additionally, a growing number of universities in the United States (e. g. , University of Arizona, Penn State University, and University of Washington), Canada, Britain, and Ireland now offer graduate degree programs in astrobiology. The University of Arizona (also referred to as UA, U of A, or Arizona) is a Land-grant and space-grant public institution The Pennsylvania State University (commonly known as Penn State) is a state-related, land-grant, space grant public research University See Washington (disambiguation for other uses The University of Washington, founded in 1861, is a public research University

The Martian meteorite ALH84001 shows formations that may have been created by life. A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface ALH 84001 (full name Allan Hills 84001) is a Meteorite found in Allan Hills, Antarctica in December 1984 by a team of US meteorite hunters from

A particular focus of current astrobiology research is the search for life on Mars. ^[14] There is a growing body of evidence to suggest that Mars has previously had a considerable amount of water on its surface; water is considered to be an essential precursor to the development of life, although this has not been conclusively proven. Water is a common Chemical substance that is essential for the survival of all known forms of Life. ^[15] At the present, the creation of theory to inform and support the exploratory search for life may be considered astrobiology's most concrete practical application.

Missions specifically designed to search for life include the Viking program and Beagle 2 probes, both directed to Mars. NASA 's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Beagle 2 was an unsuccessful British landing spacecraft that formed part of the European Space Agency 's 2003 Mars Express mission The Viking results were inconclusive, and Beagle 2 failed to transmit from the surface and is assumed to have crashed. A future mission with a strong astrobiology role would have been the Jupiter Icy Moons Orbiter, designed to study the frozen moons of Jupiter—some of which may have liquid water—had it not been canceled. The Jupiter Icy Moons Orbiter ( JIMO) was a proposed Spacecraft designed to explore the icy moons of Jupiter. In 2009, NASA plans to launch the Mars Science Laboratory Rover which will continue the search for past or present life on Mars using a suite of scientific instruments. The Mars Science Laboratory ( MSL) is a NASA rover scheduled to be launched on September 15, 2009 and perform the first ever

Research outcomes

Asteroid(s) may have transported life to Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

As of 2008, there is no direct evidence of extraterrestrial life. ^[16] Although examination of the ALH84001 meteorites, which were recovered in Antarctica and are thought to have originated from the planet Mars, have provided what some scientists suggested to be microfossils of extraterrestrial life, the interpretation is disputed. ALH 84001 (full name Allan Hills 84001) is a Meteorite found in Allan Hills, Antarctica in December 1984 by a team of US meteorite hunters from ^[17] In 2004, the spectral signature of methane was detected in the Martian atmosphere by both Earth-based telescopes as well as by the Mars Express probe. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Mars Express is a Space exploration mission being conducted by the European Space Agency (ESA Methane is predicted to have a relatively short half-life in the Martian atmosphere, so the gas must be actively replenished. Half-Life (computer-game page here It's already listed in the disambiguation page Since one possible source, active volcanism, has thus far not been detected on Mars, this has led scientists to speculate that the source could be (microbial) life—as terrestrial methanogens are known to produce methane as a metabolic byproduct. Plate tectonics and hotspots Divergent plate boundaries At the A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually Methanogens are Archaea that produce Methane as a Metabolic byproduct in Anoxic conditions Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life.

Missions to other planetary bodies, such as Mars Science Laboratory, ExoMars, Beagle 2: Evolution to Mars, the Cassini probe to Saturn's moon Titan), and the "Ice Clipper" mission to Jupiter's moon Europa, hope to further explore the possibilities of life on other planets in our solar system. The Mars Science Laboratory ( MSL) is a NASA rover scheduled to be launched on September 15, 2009 and perform the first ever ExoMars is a European-led Space exploration mission currently under development by the European Space Agency (ESA that will send a robotic rover to the Beagle 2: Evolution is the proposed successor to the unsuccessful Beagle 2 Mars lander (which disappeared during its landing in 2003) Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The Solar System consists of the Sun and those celestial objects bound to it by Gravity.

Artist's impression of Gliese 581 c, the first extrasolar planet discovered in its star's habitable zone

Efforts to answer secondary questions, such as the abundance of potentially habitable planets in habitable zones and chemical precursors, have had much success. Gliese 581 c (ˈgliːzə is a " Super-earth " An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 In Astronomy a habitable zone ( HZ) is a region of space where conditions are favorable for Life as it may be found on Earth. In Astronomy a habitable zone ( HZ) is a region of space where conditions are favorable for Life as it may be found on Earth. Numerous extrasolar planets have been detected using the "wobble method" and transit method, showing that planets around other stars are more diverse than previously postulated. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 The first Earth-like extrasolar planet to be discovered within its star's habitable zone is Gliese 581 c, which was found using radial velocity. Gliese 581 c (ˈgliːzə is a " Super-earth " Radial velocity is the Velocity of an object in the direction of the line of sight (i ^[18]

Due to technological limitations, most of the planets so far discovered have been hot gas giants, thought to be inhospitable to any life. It is possible that some of these planets may have moons with solid surfaces or oceans that are more hospitable. It is not yet known whether our solar system, with rocky, metal-rich inner planets ideal for life, is of an aberrant composition. Improved detection methods and increased observing time will undoubtedly discover more planetary systems, and possibly some more like ours. For example, NASA's Kepler Mission seeks to discover Earth-sized planets around other stars by measuring minute changes in the star's light curve as the planet passes between the star and the spacecraft. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Kepler Mission is a Space Photometer being developed by NASA. In Astronomy, a light curve is a graph of light intensity of a Celestial object or region as a function of time Research into the environmental limits of life and the workings of extreme ecosystems is also ongoing, enabling researchers to predict what planetary environments might be most likely to harbor life.

Progress in infrared astronomy and submillimeter astronomy has revealed the constituents of other star systems. Infrared astronomy is the branch of Astronomy and Astrophysics which deals with objects visible in Infrared (IR radiation Submillimetre astronomy or submillimeter astronomy (see Spelling differences) is the branch of Observational astronomy that is conducted at submillimetre Infrared searches have detected belts of dust and asteroids around distant stars, underpinning the formation of planets. Some infrared images purportedly contain direct images of planets, though this is disputed. Infrared and submillimeter spectroscopy has identified a growing number of chemicals around stars which underpin the origin or maintenance of life. Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ

Astrobiologists

• Frank Drake
• Eric Chaisson
• Thomas Gold
• David Grinspoon
• James Kasting
• Stanley Miller
• Joshua Lederberg
• Percival Lowell
• Christopher McKay
• Carl Sagan
• Mary Higby Schweitzer
• Sheikh Muszaphar Shukor
• Melissa Trainer
• Wolf Vishniac

Rare Earth hypothesis

Main article: Rare Earth hypothesis

In the book Rare Earth: Why Complex Life is Uncommon in the Universe, Peter Ward, a geologist and paleontologist, and Donald Brownlee, an extraterrestrial materials pioneer and astrobiologist, propose that life as we know it is rare in the universe. Dr Frank Donald Drake (born May 28 1930, Chicago) is an American Astronomer and Astrophysicist. Eric J Chaisson is an American Astrophysicist and science educator best known for his research teaching and writing on the interdisciplinary science of Thomas Gold ( May 22, 1920 &ndash June 22, 2004) was an Austrian born Astrophysicist, a professor of Astronomy David H Grinspoon is an American astrobiologist. He is the current Curator of Astrobiology at the Denver Museum of Nature and Science. James F Kasting (b January 2 1953 is a Geoscientist at Penn State University. Stanley Lloyd Miller ( March 7, 1930 - May 20, 2007) was an American Chemist and Biologist who is known Joshua Lederberg ( May 23, 1925 &ndash February 2, 2008) was an American molecular biologist known for his work in Percival Lawrence Lowell ( March 13, 1855 – November 12, 1916) was a businessman author mathematician and Astronomer who fueled Christopher McKay can refer to Christopher McKay (planetary scientist, planetary scientist at NASA Ames Research Center Christopher McKay (footballer Carl Edward Sagan ( November 9 1934 &ndash December 20 1996) was an American Astronomer, astrochemist, author Mary Higby Schweitzer is a Paleontologist at North Carolina State University known for leading the groups which discovered the remains of blood cells in dinosaur Datuk Dr Sheikh Muszaphar Shukor (born Sheikh Muszaphar Shukor Al Masrie bin Sheikh Mustapha on July 27, 1972) is a Malaysian orthopaedic Melissa G Trainer ( April 22, 1978 in Philadelphia Pennsylvania) is an astrobiologist who in 2004 demonstrated empirically that life could have In Planetary astronomy and Astrobiology, the Rare Earth hypothesis argues that the emergence of complex Multicellular life ( Metazoa Peter Ward may refer to Peter Ward (English footballer (born 1955 retired English footballer played for Brighton & Hove Albion and Nottingham Forest A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. ^[19][20] They suggest that microbial life, however, is probably common in the universe, because of recently discovered extremophiles. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have An extremophile is an Organism that thrives in and may even require Physically or Geochemically extreme conditions that are detrimental to the ^[21] The book argues that the chances of all the conditions that occurred to create the earth occurring again would be rare; thus intelligent life would be rare. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 One important factor focused on in the book is planetary habitability (see section below). Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life.

Peter Ward, one of the authors, said the following:^[1]

How do we define life as we do know it? Life on Earth has DNA, a specific genetic code. Peter Ward may refer to Peter Ward (English footballer (born 1955 retired English footballer played for Brighton & Hove Albion and Nottingham Forest It also uses only 20, and the same 20, amino acids. Life is always cellular according to some people, but I think not. I personally define a virus as alive. As for other life, what could it be? Could there be non-DNA life? If such life does exist, what does chemistry permit? Certainly chemistry permits certain types of life on our planet and others not. But once we move out in the solar system, especially in the vast realm of cold, chemistry changes. There could be different information systems, different solvents, different membranes. And as we go from hotter to colder, when we go to Venus, out to Mars, to Europa, and to Titan, we really should expect radically different chemistries.

Methodology

Narrowing the task

Main article: Planetary habitability

When looking for life on other planets, some simplifying assumptions are useful to reduce the size of the task of astrobiologists. Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. One is to assume that the vast majority of life forms in our galaxy are based on carbon chemistries, as are all life forms on Earth. Carbon forms the backbone of Biology for all Life on Earth. Complex Molecules are made up of carbon bonded with other elements ^[22] While it is possible that non-carbon-based life exists, carbon is well known for the unusually wide variety of molecules that can be formed around it. Alternative biochemistry is the speculative Biochemistry of alien Life forms that differ radically from those on Earth. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by However, it should be noted that astrobiology concerns itself with an interpretation of existing scientific data; that is, given more detailed and reliable data from other parts of the universe (perhaps obtainable only by physical space exploration), the roots of astrobiology itself—biology, physics, chemistry—may have their theoretical bases challenged. Much speculation is entertained in the field to give context, but astrobiology concerns itself primarily with hypotheses that fit firmly into existing theories.

This planetary habitability chart shows where life might exist on extrasolar planets based on our own Solar System and life on Earth. Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

The presence of liquid water is also a useful assumption, as it is a common molecule and provides an excellent environment for the formation of complicated carbon-based molecules that could eventually lead to the emergence of life. ^[23] Some researchers posit environments of ammonia, or more likely water-ammonia mixtures. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor ^[24] These environments are considered suitable for carbon or noncarbon life, while opening more temperature ranges (and thus worlds) for life.

A third assumption is to focus on sun-like stars. The Sun (Sol is the Star at the center of the Solar System. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth This comes from the idea of planetary habitability. Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. ^[25] Very big stars have relatively short lifetimes, meaning that life would not likely have time to evolve on planets orbiting them. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is Very small stars provide so little heat and warmth that only planets in very close orbits around them would not be frozen solid, and in such close orbits these planets would be tidally "locked" to the star. ^[26] Without a thick atmosphere, one side of the planet would be perpetually baked and the other perpetually frozen. In 2005, the question was brought back to the attention of the scientific community, as the long lifetimes of red dwarfs could allow some biology on planets with thick atmospheres. The scientific community consists of the total body of Scientists its relationships and interactions According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool Star, of the Main sequence, either late K This is significant, as red dwarfs are extremely common. See Habitability of red dwarf systems

About 10% of the stars in our galaxy are sun-like, and there are about a thousand such stars within 100 light-years of our sun. Determining the habitability of red dwarf systems could help reveal how likely Extraterrestrial life is to exist as Red dwarfs make up a majority of all the stars The Sun (Sol is the Star at the center of the Solar System. These stars would be useful primary targets for interstellar listening. Since Earth is the only planet known to contain life, there is no way to know if any of the simplifying assumptions are correct.

Divisions of astrobiology

Astronomy

Main article: Astronomy

Artist's impression of the extrasolar planet OGLE-2005-BLG-390Lb (with surface temperature of −220°C) orbiting its star 20,000 light-years (117. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by 5 quadrillion miles) from Earth; this planet was discovered with gravitational microlensing. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

The planned NASA Kepler mission for the search of extrasolar planets

Most astronomy-related astrobiological research falls into the category of extrasolar planet (exoplanet) detection, the hypothesis being that if life arose on Earth then it could also arise on other planets with similar characteristics. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Kepler Mission is a Space Photometer being developed by NASA. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 To that end, a number of instruments designed to detect Earth-like exoplanets are under development, most notably NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin programs. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Terrestrial Planet Finder ( TPF) was a plan by the National Aeronautics and Space Administration of the United States for a Telescope The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member The Darwin Mission is a proposed European Space Agency (ESA program designed to directly detect Earth -like planets orbiting nearby stars, and search for ^[27] Additionally, NASA plans to launch the Kepler mission in 2008, and the French Space Agency has already launched the COROT space mission. The Kepler Mission is a Space Photometer being developed by NASA. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common The fr '''Centre National d'Études Spatiales''' ( CNES) is the French government Space agency (administratively a "public establishment of industrial and commercial COROT ( CO nvection RO tation and planetary T ransits is a space mission led by the French Space Agency (CNES in conjunction with the European ^[28][29] There are also several less ambitious ground-based efforts underway (see exoplanet). An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312

The goal of these missions is not only to detect Earth-sized planets, but also to directly detect light from the planet so that it may be studied spectroscopically. Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ By examining planetary spectra, it would be possible to determine the basic composition of an extrasolar planet's atmosphere and/or surface; given this knowledge, it may be possible to assess the likelihood of life being found on that planet. A NASA research group, the Virtual Planet Laboratory[1] (VPL), is using computer modelling to generate a wide variety of virtual planets to see what they would look like if viewed by TPF or Darwin. It is hoped that once these missions come online, their spectra can be cross-checked with these virtual planetary spectra for features that might indicate the presence of life. The photometry temporal variability of extrasolar planets may also provide clues to their surface and atmospheric properties. Photometry is a technique of Astronomy concerned with measuring the Flux, or intensity of an Astronomical object 's Electromagnetic One mission was planned to Jupiter's moon Europa before recent cuts by NASA. This mission would have searched for life in the ocean of this moon.

An estimate for the number of planets with (intelligent) extraterrestrial life can be gleaned from the Drake equation, essentially an equation expressing the probability of intelligent life as the product of factors such as the fraction of planets that might be habitable and the fraction of planets on which life might arise:^[30]

However, whilst the rationale behind the equation is sound, it is unlikely that the equation will be constrained to reasonable error limits any time soon. The Drake equation (also sometimes called the "Green Bank equation" the "Green Bank Formula" or often erroneously labeled the " Sagan equation" The first term, Number of Stars, is generally constrained within a few orders of magnitude. The second and third terms, Stars with Planets and Planets with Habitable Conditions, are being evaluated for the sun's neighbourhood. Another associated topic is the Fermi paradox, which suggests that if intelligent life is common in the universe, then there should be obvious signs of it. The Fermi paradox is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for This is the purpose of projects like SETI, which tries to detect signs of radio transmissions from intelligent extraterrestrial civilizations. Search for Extra-Terrestrial Intelligence ( SETI) is the collective name for a number of activities to detect intelligent Extraterrestrial life.

Another active research area in astrobiology is solar system formation. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. It has been suggested that the peculiarities of our solar system (for example, the presence of Jupiter as a protective shield or the planetary collision which created the moon) may have greatly increased the probability of intelligent life arising on our planet. ^[31][32] No firm conclusions have been reached so far. The role of Jupiter may be controversial. [2]

Biology

Main article: Biology

Hydrothermal vents are able to support extremophilic bacteria on Earth and may also support life in other parts of the universe. Foundations of modern biology There are five unifying principles A hydrothermal vent is a Fissure in a planet's surface from which geothermally heated Water issues An extremophile is an Organism that thrives in and may even require Physically or Geochemically extreme conditions that are detrimental to the EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

Extremophiles (organisms able to survive in extreme environments) are a core research element for astrobiologists. An extremophile is an Organism that thrives in and may even require Physically or Geochemically extreme conditions that are detrimental to the Such organisms include biota able to survive kilometers below the ocean's surface near hydrothermal vents and microbes that thrive in highly acidic environments. Biota is the total collection of Organisms of a geographic region or a time period from local geographic scales and instantaneous temporal scales all the way up to whole-planet A hydrothermal vent is a Fissure in a planet's surface from which geothermally heated Water issues A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually ^[33] Characterization of these organisms—their environments and their evolutionary pathways—is considered a crucial component to understanding how life might evolve elsewhere in the universe. Recently, a number of astrobiologists have teamed up with marine biologists and geologists to search for extremophiles and other organisms living around hydrothermal vents on the floors of our own oceans. Scientists hope to use their findings to help them create hypotheses on whether life could potentially exist on certain moons in our own solar system, such as Europa. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as ^[34][35][36]

The origin of life, as distinct from the evolution of life, is another ongoing field of research. Oparin and Haldane postulated that the conditions on the early earth were conducive to the formation of organic compounds from inorganic precursors and thus to the formation of many of the chemicals common to all forms of life we see today. Alexander Ivanovich Oparin (Алекса́ндр Ива́нович Опарин ( Uglich, Russia &ndash April 21, 1980, Moscow The study of this process, known as prebiotic chemistry, has made some progress, but it is still unclear whether or not life could have formed in such a manner on Earth. The alternative theory of panspermia is that the first elements of life may have formed on another planet with even more favourable conditions (or even in interstellar space, asteroids, etc. Panspermia ( Gk. πάς/πάν (pas/pan all and σπέρμα ( sperma, seed is the Hypothesis that "seeds" of Life exist already ) and then have been carried over to Earth by a variety of means.

Geology

Main article: Geology

The fossil record provides the oldest known evidence for life on Earth. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. ^[37] By examining this evidence, geologists are able to understand better the types of organisms that arose on the early earth. Some regions on Earth, such as the Pilbara in Western Australia and the McMurdo Dry Valleys^[38] of Antarctica, are also considered to be geological analogs to regions of Mars and as such might be able to provide clues to possible Martian life. For the Fly Genus, see Pilbara (fly. The Pilbara is a Western Australia is a state occupying the entire western third of the Australian continent. "Dry valleys" redirects here For other uses see Dry valley The McMurdo Dry Valleys are a row of Valleys in Scientists have long speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth.

Life in the Solar System

See also: Life on Mars, Life on Europa, and Life on Titan

Europa, due to the ocean that exists under its icy surface, might host some form of microbial life. Scientists have long speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have

The three most likely candidates for life in the solar system (besides Earth) are the planet Mars, the Jovian moon Europa, and Saturn's moon Titan. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as ^{[39][40][41][42][43]} This speculation is primarily based on the fact that (in the cases of Mars and Europa) the planetary bodies may have liquid water, a molecule essential for life as we know it for its use as a solvent in cells. A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. ^[44] Water on Mars is found in its polar ice caps, and newly carved gullies recently observed on Mars suggest that liquid water may exist, at least transiently, on the planet's surface,^{[45] [46]} and possibly in subsurface environments such as hydrothermal springs as well. At the Martian temperatures and pressures, such liquid water is likely to be highly saline. ^[47] As for Europa, liquid water likely exists beneath the moon's icy outer crust. ^[48] This water may be warmed to a liquid state by volcanic vents on the ocean floor (an especially intriguing theory considering the various types of extremophiles that live near Earth's volcanic vents), but the primary source of heat is probably tidal heating. Tidal acceleration is an effect of the Tidal forces between an orbiting Natural satellite ( i ^[49][50]

Another planetary body that could potentially sustain extraterrestrial life is Saturn's largest moon, Titan. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as ^[43] Titan has been described as having conditions similar to those of early Earth; according to bbc. co. uk, "The atmosphere on Titan could be identical to that of the early Earth when life began". ^[51] On Titan, scientists have discovered the first liquid lakes outside of Earth, but they are made of ethane and methane, not water. ETHANE is a mnemonic indicating a protocol used by Emergency services to report situations which they may be faced with especially as it relates to major incidents where Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. ^[52] On March 20, 2008, it was reported that Titan may have an underground ocean of water and ammonia after Cassini data was studied. Events 1600 - The Linköping Bloodbath takes place on Maundy Thursday in Linköping, Sweden. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Water is a common Chemical substance that is essential for the survival of all known forms of Life. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor ^[53] Additionally, Saturn's moon Enceladus may have an ocean below its icy surface. TemplateInfobox Planet.--> This article is about the moon of ^[54]

Political influence

In the United States, President George W. Bush's Fiscal Year 2007 NASA Budget cut funding for astrobiological research by 50 percent. The United States of America —commonly referred to as the George Walker Bush ( born July 6 1946 is the forty-third and current President of the United States. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. ^[55] In the 2007 plan, $89 million will be cut from astrobiological research, partly because of a $2. 3 billion error in the Space Shuttle Budget. ^[56] In a letter to the astrobiological community in the United States, SETI chief executive Thomas Pierson and former NAI director Baruch Blumberg said the following: "Action is needed immediately to prevent the slowing down, or even cessation, of astrobiological research". The United States of America —commonly referred to as the Search for Extra-Terrestrial Intelligence ( SETI) is the collective name for a number of activities to detect intelligent Extraterrestrial life. ^[56] Hiroshi Ohmoto, the director of the Astrobiology Research Center in Penn State, said the following in response to the budget cuts to astrobiology:^[56]

Astrobiology is the reason we go into space, to answer fundamental questions about the origins of life and how it evolved, and whether there are other places where organisms are living. It is the whole justification for future space missions.

Criticisms

Because astrobiology relies mostly on scientific extrapolations over solid, factual evidence, the authenticity of astrobiology as a science can be questioned. While other branches of science remain heavily hypothetical, there is a greater degree of mathematical, pragmatic and/or observational evidence supporting the theories. For example, while science cannot prove string theory, there is a great deal of mathematical computation which implies the existence of strings of energy. String theory is a still-developing scientific approach to Theoretical physics, whose original building blocks are one-dimensional extended objects called strings Such evidence does not exist with astrobiology, save for an asteroid segment which is believed to have fossilized Martian microbes. Although some have thought a formal degree program in astrobiology unlikely, ^[57] the University of Glamorgan, UK, started just such a degree in 2006. The University of Glamorgan (Prifysgol Morgannwg is a University in Pontypridd (in the former County of Mid Glamorgan) Wales with campuses ^[58]

Characterization of non-Earth life is extraordinarily unsettled; hypotheses and predictions as to its existence and origin vary wildly; true astrobiological experiments (with modest exceptions such as the study of the ALH84001 meteorite and searches for indications of life in Earthshine) simply cannot occur at present. ALH 84001 (full name Allan Hills 84001) is a Meteorite found in Allan Hills, Antarctica in December 1984 by a team of US meteorite hunters from The phenomenon known as planetshine occurs when reflected Sunlight from a Planet illuminates the dark side of one of its moons Typically this Finally, astrobiology has been criticized for being unimaginative in the tacit assumption that Earth-like life presents the most likely template for life elsewhere. Evolving the Alien The Science of Extraterrestrial Life (2002 published in the US and UK second edition as What Does a Martian Look Like? The Science of Extraterrestrial For example, Michael Crow, the president of Arizona State University, said the following:^[59]

For the last 3,000 years of our science, we really haven't gotten around to the notion that there might be something going on somewhere other than in this small, rural village [called Earth], in this isolated corner of our own galaxy or the Universe itself.

The reference to the universe itself is because our universe may be part of a larger Multiverse where other types of life could exist. The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy The multiverse (or meta-universe) is the hypothetical set of multiple possible Universes (including our universe that together comprise all of Reality.

Biologist Jack Cohen and mathematician Ian Stewart, amongst others, consider xenobiology separate from astrobiology for this reason. A biologist is a Scientist devoted to and producing results in Biology through the study of Organisms Typically biologists study organisms and their relationship Jack Cohen may refer to Jack Cohen (Tesco (1898&ndash1979 British businessman Jack Cohen (politician (1886&ndash1965 British Conservative A mathematician is a person whose primary area of study and research is the field of Mathematics. Ian Nicholas Stewart (born 1945) is a professor of Mathematics at University of Warwick, England and a widely known popular-science and science-fiction Cohen and Stewart stipulate that astrobiology is the search for Earth-like life outside of our solar system and say that xenobiologists are concerned with the possibilities open to us once we consider that life need not be carbon-based or oxygen-breathing, so long as it has the defining characteristics of life. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism See carbon chauvinism. Carbon chauvinism is a relatively new term meant to disparage the assumption that Extraterrestrial life will resemble life on Earth

As with all space exploration, there is the classic argument that there is still a lot more scientists have to learn about Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Critics of astrobiology may prefer that federal funding remain dedicated towards searching for unknown species in our own terrestrial biosphere. The biosphere is the broadest level of ecological study the global sum of all Ecosystems. They feel that Earth is the most plausible and practical region to search for and study life.

Publications

• The International Journal of Astrobiology, published by Cambridge University Press, is the forum for practitioners in this interdisciplinary field. Cambridge University Press (known colloquially as CUP is a Publisher given a Royal Charter by Henry VIII in 1534
• Astrobiology, published by Mary Ann Liebert, Inc., is the leading peer-reviewed international journal created as a forum for scientists seeking to advance our understanding of life's origin, evolution, and distribution in the universe. Mary Ann Liebert Inc is a publishing company founded by its President, Mary Ann Liebert in 1980 Astrobiology brings together researchers through the dissemination of original research, hypothesis, education articles, and reviews.
• Grinspoon, David (2003). Lonely planets. The natural philosophy of alien life. New York: ECCO. ISBN 0060185406.  
• Jakosky, Bruce M. (2006). Science, Society, and the Search for Life in the Universe. Tucson: University of Arizona Press. ISBN 0816526133.  
• Lunine, Jonathan I. (2005). Astrobiology. A Multidisciplinary Approach. San Francisco: Pearson Addison-Wesley. ISBN 0805380426.  

See also

References

http://www.europlanet-eu.org/index.php?option=com_content&task=view&id=102&I

External links

• Astrobiology Instant Expert on New Scientist
• Astrobiology@home
• The Astrobiology Web
• Astrobiology Magazine
• NASA Astrobiology Institute
• Possible Connections Between Interstellar Chemistry and the Origin of Life on the Earth
• Scientists Find Clues That Life Began in Deep Space - NASA Astrobiology Institute
• Stars and Habitable Planets
• Influenza 1918, A Venus Connection?
• NASA-Macquarie University Pilbara Education Project
• Conditions for Life Everywhere
• Snaiad, a world-building project with creatures designed with evolutionary biology in mind.
• Astrobiology Lecture Course Network (a.y. 2005-2006)