Astrobiology

Alternative biochemistry collectively refers to an assortment of astrobiology theories and hypotheses in which life is based on chemical systems other than those used by currently known forms of life. Proponents of such theories sometimes use the expression carbon chauvinism to disparage the assumption that carbon molecules are necessarily the basis for all life. Up to this point, however, no non- carbon based life-form has been discovered. ...more on Wikipedia about "Alternative biochemistry"

Astrobiology is an interdisciplinary field, combining aspects of astronomy, biology and geology, which is focused primarily on the study of the origin, distribution and evolution of life. It comes from the Greek words astron = star, bios = life and logos = word/science), and is also known as exobiology ( Greek: exo = out) or xenobiology ( Greek: xenos = foreign). ...more on Wikipedia about "Astrobiology"

Back-contamination is the informal but widely-employed name for the introduction of microbial extraterrestrial organisms into Earth's biosphere. It is assumed that any such contact will be disruptive or at least have consequences over which human beings will have little control. The threat of back-contamination from the Moon was the main reason for quarantine procedures adopted for the Apollo program which are now considered standard procedure ** . ...more on Wikipedia about "Back-contamination"

A Biosignature, generally, is a measurable phenomenon that indicates the presence of life. The term biomarker is sometimes used as a synonym. ...more on Wikipedia about "Biosignature"

Carbon forms the backbone of biology for all life on Earth. Complex molecules are made up of carbon bonded with other elements, especially oxygen, hydrogen and nitrogen. It is these elements that living organisms need, among others, and carbon is able to bond with all of these because of its four valence electrons. Since no life has been observed that is not carbon-based, it is sometimes assumed in astrobiology that life elsewhere in the universe will also be carbon-based. This assumption is referred to by critics as carbon chauvinism, as it may be possible for life to form that is not based on carbon. ...more on Wikipedia about "Carbon based life"

CHON is an mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen, oxygen, and nitrogen. These four elements are also notable for being the least massive (and having the lowest atomic number) in their group in the periodic table. ...more on Wikipedia about "CHON"

Evolving the Alien: The Science of Extraterrestrial Life (2002, second edition published as What Does a Martian Look Like? The Science of Extraterrestrial Life) is a book about xenobiology by biologist Jack Cohen and mathematician Ian Stewart. ...more on Wikipedia about "Evolving the Alien"

Extraterrestrial life is life that may exist and originate outside the planet Earth. Its existence is currently hypothetical: there is as yet no evidence of extraterrestrial life that has been widely accepted by scientists. ...more on Wikipedia about "Extraterrestrial life"

Forward-contamination is the accidental contamination of other worlds with Earth microbes. The risk of forward-contamination is twofold: that human beings may accidentally seed a previously sterile world, thus creating " extraterrestrials" that are really of terrestrial origin; or that an actual alien biosphere could be devastated by Earth bacteria and viruses. ...more on Wikipedia about "Forward-contamination"

Scientists have long speculated about the possibility of life on Mars due to that planet's proximity and similarity to Earth. It remains an open question whether life exists on Mars now, or existed there in the past. ...more on Wikipedia about "Life on Mars"

Description: Henry Gray's Anatomy of the Human Body, commonly known as Gray's Anatomy, is an anatomy textbook widely regarded as a classic work on human anatomy. The book was first published under the title Gray's Anatomy: Descriptive and Surgical in Great Britain in 1858, and the following year in the United States. The book's British author died after the publication of the 1860 second edition, at the age of 34, but his much-praised book was continued by others and on November 24, 2004, the 39th British edition was released. ...more on Wikipedia about "List of publications in biology"

The Lunar Receiving Laboratory (LRL) is a facility at NASA's Lyndon B. Johnson Space Center (Building 37) that was constructed to quarantine astronauts and material brought back from the Moon during the Apollo program. After recovery at sea, crews from Apollo 11, Apollo 12 and Apollo 14 walked from their helicopter to an isolation van on the deck of an aircraft carrier and were brought to the LRL for quarantine. Samples of rock and soil that the astronauts collected and brought back were flown directly to the LRL and initially analyzed in glove box vacuum chambers. ...more on Wikipedia about "Lunar Receiving Laboratory"

The Murchison meteorite is named after Murchison, Victoria in Australia. Fragments of the meteorite fell near the village on 28 September 1969. The meteorite, a type II carbonaceous chondrite, was found to contain common amino acids such as glycine, alanine and glutamic acid but also unusual ones like isovaline and pseudoleucine [1]. The initial report stated that the amino acids were racemic supporting a theory that the source is extraterrestrial. A complex mixture of alkanes was isolated as well which was similar to that found in the Miller-Urey experiment. Serine and threonine are usually considered earthly contaminants and these compounds were conspicuously absent in the samples. ...more on Wikipedia about "Murchison meteorite"

The NASA Astrobiology Institute (NAI) engages in government-funded xenobiologic study of the living universe. Advances in science and technology are yielding dramatic new knowledge about the origin, distribution, and destiny of life. Scientists have analyzed complex organic chemistry in interstellar clouds of gas and dust and have discovered more than 200 planets outside of our solar system. Life on Earth has been found thriving at environmental extremes such as in Antarctic rocks, boiling hot springs, and aquifers buried kilometers below the land surface. We have found that liquid water, the one essential ingredient for life as we know it, once flowed on the surface of the planet Mars and exists today below the icy crust of Jupiter's moon, Europa. Life on Earth has been traced back 3.8 billion years to the period of heavy cometary bombardment, an era that simultaneously brought life-giving water and organic compounds to the terrestrial planets while battering them with lethal quantities of impact energy. We are discovering both the fragility and robustness of life as we investigate the history of mass extinctions on our planet, recent extinctions, and subtle alterations in climate triggered by volcanic eruptions and human industry. ...more on Wikipedia about "NASA Astrobiology Institute"

Paleocontact theory is a term used to describe the hypothesis that intelligent extraterrestrial creatures visited Earth in the distant past or at the dawn of human civilization. Carl Sagan, I.S. Shklovskii, and Hermann Oberth are three notable scientists who have seriously considered the possibility of extraterrestial visitations in Earth's past. Although this is often popularly described as a " theory", according to scientific method it is not yet at that stage of proof, because the fossil and archeological records merely leave open the possibility rather than establishing a testable prediction. ...more on Wikipedia about "Paleocontact theory"

Panspermia is the hypothesis that the seeds of life are ubiquitous in the universe, that they may have delivered life to Earth, and that they may deliver or have delivered life to other habitable bodies; also the process of such delivery. ...more on Wikipedia about "Panspermia"

Planetary habitability is the measure of an astronomical body's potential to develop and sustain life. It may be applied both to planets and to the natural satellites of planets. ...more on Wikipedia about "Planetary habitability"

The rare Earth hypothesis is a response to the Fermi paradox which explains why we might expect a planet such as Earth to be very rare. Combined with the additional assumption that an Earth-like planet is a prerequisite for the development of advanced life, this offers an explanation for the current lack of evidence of extraterrestrial civilizations. ...more on Wikipedia about "Rare Earth hypothesis"

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