Astrobiology

thumb|Nucleic acids may not be the only [[biomolecules in the universe capable of coding for life processes.]]

life that does not originate from Earth

apparent contradiction between the lack of evidence and high probability estimates for the existence of extraterrestrial civilizations

thumb|upright=2|Stages in the origin of life process range from the well understood, such as the planetary habitability|habitable Earth and the abiotic synthesis of simple molecules, to the largely unknown, like the derivation of the [[last universal common ancestor (LUCA) with its complex molecular functionalities.]]

dust floating in space

right|thumb|300px|The bright colors of Grand Prismatic Spring in [[Yellowstone National Park are produced by thermophiles, a type of extremophile.]]

effort to find civilizations not from Earth

probabilistic argument to estimate the number of alien civilizations in our galaxy

thumb |upright=1.3 |Panspermia proposes that organisms such as [[bacteria, complete with their DNA, could be transported by means such as comets through space to planets including Earth.]] Panspermia () is the hypothesis that life exists throughout the universe, distributed by cosmic dust, meteoroids, asteroids, comets, and planetoids, as well as by spacecraft carrying unintended contamination by microorganisms, known as directed panspermia. The theory argues that life did not originate on Earth, but instead evolved somewhere else and seeded life as we know it.

pair of NASA space probes sent to Mars

Martian meteorite found in Antarctica in 1984

life on the planet Mars

degree to which a planet is suitable for life, or study of planets which may be so suited

hypothesis that complex extraterrestrial life is a very improbable phenomenon and likely to be extremely rare

large multi radio telescope project aimed to be built in Australia and South Africa

volcano in Ethiopia

A biosignature is a phenomenon that can be explained by biological processes where all possible abiotic causes of this phenomenon have been eliminated. This term is mainly used in the field of astrobiology in the search for past or present extraterrestrial life, from planets and moons in the Solar System to exoplanets. Candidate biosignatures strongly indicate some of the earliest known life forms, aid studies of the origin of life on Earth as well as the possibility of life on Mars, Venus and elsewhere in the universe.

life on the planet Venus

human spaceflight programme of the European Space Agency

hypothesis that alien life has not been discovered because alien civilizations are silent and very cautious

hypothetical possibility

possible alternative biochemicals used by life forms

hypothetical type of planet that may be better-suited for life than Earth is

chemical elements or compounds with low boiling points associated with planet’s or moon’s crust or atmosphere

synthetic nucleic acid (eight nucleobases — four natural, and four synthetic)

species of bacterium

Martian meteorite discovered in India

satellite

assumption that the chemical processes of hypothetical extraterrestrial life must be constructed primarily from carbon

guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth

belief in numerous life-bearing "worlds"

integrated field of astronomical science

thumb|400px|Illustration of various types of technosignatures Technosignature or technomarker is any measurable property or effect that provides scientific evidence of past or present technology. Technosignatures are analogous to biosignatures, which signal the presence of life, whether intelligent or not. Some authors prefer to exclude radio transmissions from the definition, but such restrictive usage is not widespread. Jill Tarter has proposed that the search for extraterrestrial intelligence (SETI) be renamed "the search for technosignatures". Various types of technosignatures, such as rad

1864 carbonaceous chondrite meteorite fall in southwestern France

putative site of small gas and dust eruptions that occur in the south polar region of Mars during the spring thaw

meteorite found in Antarctica

assessment of modern science's ability to detect evidence of a prior advanced civilization

overview of the habitability of K-type main-sequence star systems

Earth history between 1.8 and 0.8 billion years ago, characterized by tectonic stability, climatic stasis, and a slow biological evolution with very low oxygen levels and no evidence of glaciation

life whose primary component is carbon

astrobiological hypothesis that life forms of early Earth were retinal-based rather than chlorophyll-based, making Earth appear purple rather than green

idea that any intelligent life is destroyed by aliens

thumb|A zucchini being grown on the International Space StationAstrobotany is an applied sub-discipline of botany that is the study of plants in space environments. It is a branch of astrobiology and botany.

Xenoarchaeology, a branch of xenology dealing with extraterrestrial cultures, is a hypothetical form of archaeology that exists mainly in works of science fiction. The field is concerned with the study of the material remains to reconstruct and interpret past life-ways of alien civilizations. Xenoarchaeology is not currently practiced by mainstream archaeologists due to the current lack of any material for the discipline to study.

region of rapid change in reflectance of vegetation in the near infrared range of the electromagnetic spectrum

hypothetical microbial biosphere of Earth that would use radically different biochemical and molecular processes from that of currently known life

star

organization

Martian meteorite found in Antarctica in 1977

martian rock noted for its potential life signs

Institute for the search of habitable worlds

biological contamination of a planetary body by a space probe or spacecraft

SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations) is a Search for Extra-Terrestrial Intelligence (SETI) program originated by the Berkeley SETI Research Center at the University of California, Berkeley.

thumb|right|200px|Gamma-ray bursts might have regulated the advent of intelligent life Neocatastrophism is the hypothesis that life-exterminating events such as gamma-ray bursts have acted as a galactic regulation mechanism in the Milky Way upon the emergence of complex life in its habitable zone. It is one of several proposed solutions to the Fermi paradox since it provides a mechanism which would have delayed the advent of intelligent beings in local galaxies near Earth.

laboratory at the Johnson Space Ceneter

lake in British Columbia, Canada

Hemolithin (sometimes confused with the similar space polymer hemoglycin) is a proposed protein containing iron and lithium, of extraterrestrial origin, according to an unpublished preprint. The result has not been published in any peer-reviewed scientific journal. The protein was purportedly found inside two CV3 meteorites, Allende and Acfer-086, by a team of scientists led by Harvard University biochemist Julie McGeoch. The report of the discovery was met with some skepticism and suggestions that the researchers had extrapolated too far from incomplete data.

British physicist

thumb|Deep Phreatic Thermal Explorer The Deep Phreatic Thermal Explorer (DEPTHX) is an autonomous underwater vehicle designed and built by Stone Aerospace, an aerospace engineering firm based in Austin, Texas. It was designed to autonomously explore and map underwater sinkholes in northern Mexico, as well as collect water and wall core samples. This could be achieved via an autonomous form of navigation known as A-Navigation. The DEPTHX vehicle was the first of three vehicles to be built by Stone Aerospace which were funded by NASA with the goal of developing technology that can explore the oc

Study of the effects gravity has on living organisms