Editing Astrobiology (section)

== Overview ==

The term astrobiology was first proposed by the [[Soviet Union|Russian]] astronomer [[Gavriil Adrianovich Tikhov|Gavriil Tikhov]] in 1953.<ref>{{Cite journal|last=Cockell |first=Charles S. |title='Astrobiology' and the ethics of new science |url=https://www.researchgate.net/publication/42790151 |date=2001 |journal=Interdisciplinary Science Reviews  |volume=26 |issue=2 |pages=90–96 |doi=10.1179/0308018012772533 }}</ref> It is etymologically derived from the [[Ancient Greek|Greek]] {{lang|grc|ἄστρον}}, "star"; {{lang|grc|βίος}}, "life"; and {{lang|grc|-λογία}}, ''[[wikt:-logia|-logia]]'', "study". A close synonym is exobiology from the [[Ancient Greek|Greek]] Έξω, "external"; {{lang|grc|βίος}}, "life"; and {{lang|grc|-λογία}}, ''[[wikt:-logia|-logia]]'', "study", coined by American molecular biologist [[Joshua Lederberg]]; exobiology is considered to have a narrow scope limited to search of life external to Earth.<ref>[http://profiles.nlm.nih.gov/ps/retrieve/Narrative/BB/p-nid/32 Launching a New Science: Exobiology and the Exploration of Space] ''The National Library of Medicine''.</ref> Another associated term is [[xenobiology]], from the Greek ξένος, "foreign"; {{lang|grc|βίος}}, "life"; and -λογία, "study", coined by American science fiction writer [[Robert Heinlein]] in his 1954 work ''[[The Star Beast (novel)|The Star Beast]]'';<ref>{{cite journal |vauthors=Heinlein R, Harold W|title=Xenobiology |journal=Science |date=21 July 1961 |pages=223–225 | doi=10.1126/science.134.3473.223 |pmid=17818726 |jstor=1708323 |volume=134 |issue=3473|bibcode = 1961Sci...134..223H }}</ref> xenobiology is now used in a more specialised sense, referring to 'biology based on foreign chemistry', whether of extraterrestrial or terrestrial (typically synthetic) origin.<ref>{{cite journal | author=Markus Schmidt | title=Xenobiology: A new form of life as the ultimate biosafety tool | journal=BioEssays | date=9 March 2010 | pages=322–331 | doi=10.1002/bies.200900147 | volume=32 | issue=4 | pmid=20217844 | pmc=2909387 }}</ref>

While the potential for extraterrestrial life, especially intelligent life, has been explored throughout human history within philosophy and narrative, the question is a verifiable [[hypothesis]] and thus a valid line of [[science|scientific]] inquiry;<ref name="NAT-20170216">{{cite journal |last=Livio |first=Mario |title=Winston Churchill's essay on alien life found |date=15 February 2017 |journal=[[Nature (journal)|Nature]] |volume=542 |issue=7641 |pages=289–291 |doi=10.1038/542289a |pmid=28202987 |bibcode = 2017Natur.542..289L |s2cid=205092694 |doi-access=free }}</ref><ref name="NYT-20170215">{{cite news |last=De Freytas-Tamura |first=Kimiko |title=Winston Churchill Wrote of Alien Life in a Lost Essay |url=https://www.nytimes.com/2017/02/15/world/europe/winston-churchill-aliens.html |archive-url=https://ghostarchive.org/archive/20220101/https://www.nytimes.com/2017/02/15/world/europe/winston-churchill-aliens.html |archive-date=2022-01-01 |url-access=limited |date=15 February 2017 |work=[[The New York Times]] |access-date=18 February 2017 }}{{cbignore}}</ref> planetary scientist David Grinspoon calls it a field of natural philosophy, grounding speculation on the unknown in known scientific theory.<ref>Grinspoon 2004</ref>

The modern field of astrobiology can be traced back to the 1950s and 1960s with the advent of [[space exploration]], when scientists began to seriously consider the possibility of life on other planets. In 1957, the [[Soviet Union]] launched [[Sputnik 1]], the first artificial satellite, which marked the beginning of the [[Space Age]]. This event led to an increase in the study of the potential for life on other planets, as scientists began to consider the possibilities opened up by the new technology of space exploration. In 1959, NASA funded its first exobiology project, and in 1960, NASA founded the Exobiology Program, now one of four main elements of NASA's current Astrobiology Program.<ref>{{cite web |last1=Hubbard |first1=G. Scott |title=Astrobiology: Its Origins and Development |url=https://www.nasa.gov/50th/50th_magazine/astrobiology.html |website=NASA |access-date=29 January 2023 |archive-date=28 June 2022 |archive-url=https://web.archive.org/web/20220628064139/https://www.nasa.gov/50th/50th_magazine/astrobiology.html |url-status=dead }}</ref> In 1971, NASA funded [[Project Cyclops]],<ref>{{cite web |title=Project Cyclops: a Design Study of a System for Detecting Extraterrestrial Intelligent Life |date=January 1972 |url=https://ntrs.nasa.gov/citations/19730010095 |publisher=NASA |access-date=29 January 2023}}</ref> part of the [[SETI|search for extraterrestrial intelligence]], to search radio frequencies of the electromagnetic spectrum for interstellar communications transmitted by extraterrestrial life outside the Solar System. In the 1960s-1970s, NASA established the [[Viking program]], which was the first US mission to land on Mars and search for metabolic signs of present life; the results were inconclusive.

In the 1980s and 1990s, the field began to expand and diversify as new discoveries and technologies emerged. The discovery of microbial life in extreme environments on Earth, such as deep-sea hydrothermal vents, helped to clarify the feasibility of potential life existing in harsh conditions. The development of new techniques for the detection of biosignatures, such as the use of stable isotopes, also played a significant role in the evolution of the field.

The contemporary landscape of astrobiology emerged in the early 21st century, focused on utilising Earth and environmental science for applications within comparate space environments. Missions included the ESA's [[Beagle 2]], which failed minutes after landing on Mars, NASA's [[Phoenix lander|''Phoenix'' lander]], which probed the environment for past and present planetary habitability of microbial life on Mars and researched the history of water, and NASA's [[Curiosity rover|''Curiosity'' rover]], currently probing the environment for past and present planetary habitability of microbial life on Mars.