Editing Venus (section)

==Search for life==
{{Main|Life on Venus}}

Speculation on the possibility of life on Venus's surface decreased significantly after the early 1960s when it became clear that conditions were extreme compared to those on Earth. Venus's extreme temperatures and atmospheric pressure make water-based life, as currently known, unlikely.

Some scientists have speculated that thermoacidophilic [[extremophile]] [[microorganism]]s might exist in the cooler, acidic upper layers of the Venusian [[Atmosphere of Venus|atmosphere]].<ref name=Clark_2003/><ref name=Redfern_2004/><ref name="Dartnell2015"/> Such speculations go back to 1967, when [[Carl Sagan]] and [[Harold J. Morowitz]] suggested in a ''[[Nature (journal)|Nature]]'' article that tiny objects detected in Venus's clouds might be organisms similar to Earth's bacteria (which are of approximately the same size):
:While the surface conditions of Venus make the hypothesis of life there implausible, the clouds of Venus are a different story altogether. As was pointed out some years ago, water, [[carbon dioxide]] and sunlight—the prerequisites for [[photosynthesis]]—are plentiful in the vicinity of the clouds.<ref name=Sagan_Morowitz_1967/>

In August 2019, astronomers led by Yeon Joo Lee reported that long-term pattern of absorbance and [[albedo]] changes in the atmosphere of the planet Venus caused by "unknown absorbers", which may be chemicals or even large colonies of microorganisms high up in the atmosphere of the planet, affect the climate.<ref name="TAJ-20190826"/> Their [[Light absorption|light absorbance]] is almost identical to that of micro-organisms in Earth's clouds. Similar conclusions have been reached by other studies.<ref name="ES-20190903"/>

In September 2020, a team of astronomers led by [[Jane Greaves]] from [[Cardiff University]] announced the likely detection of [[phosphine]], a gas not known to be produced by any known chemical processes on the Venusian surface or atmosphere, in the upper levels of the planet's clouds.<ref name=Bains_et_al_2021/><ref name=Greaves_et_al_2020/><ref name=Drake_2020/><ref name=Perkins_2020/><ref name=Seager_et_al_2020/> One proposed source for this phosphine is living organisms.<ref name="Sample1"/> The phosphine was detected at heights of at least {{convert|30|mi|km}} above the surface, and primarily at mid-latitudes with none detected at the poles. The discovery prompted [[NASA]] administrator [[Jim Bridenstine]] to publicly call for a new focus on the study of Venus, describing the phosphine find as "the most significant development yet in building the case for life off Earth".<ref name=Kooser_2020/><ref name=Bridenstine_2020/>

Subsequent analysis of the data-processing used to identify phosphine in the atmosphere of Venus has raised concerns that the detection-line may be an artefact. The use of a 12th-order polynomial fit may have amplified noise and generated a false reading (see [[Runge's phenomenon]]). Observations of the atmosphere of Venus at other parts of the electromagnetic spectrum in which a phosphine absorption line would be expected did not detect phosphine.<ref name="Plait1"/> By late October 2020, re-analysis of data with a proper subtraction of background did not show a [[statistically significant]] detection of phosphine.<ref name=Snellen_et_al_2020/><ref name=Thompson2020/><ref name=Cordiner_et_al_2021/>

Members of the team around Greaves, are working as part of a project by the [[MIT]] to send with the rocket company [[Rocket Lab]] the first private interplanetary space craft, to look for organics by entering the atmosphere of Venus with a probe named [[Venus Life Finder]].<ref name="Venus Cloud Life - MIT 2023">{{cite web | title=Rocket Lab Probe | website=Venus Cloud Life – MIT | date=7 March 2023 | url=https://venuscloudlife.com/small-mission/ | access-date=13 May 2023 | archive-date=8 February 2024 | archive-url=https://web.archive.org/web/20240208040505/https://venuscloudlife.com/small-mission/ | url-status=live }}</ref>

===Planetary protection===
The [[Committee on Space Research]] is a scientific organization established by the [[International Council for Science]]. Among their responsibilities is the development of recommendations for avoiding [[interplanetary contamination]]. For this purpose, space missions are categorized into five groups. Due to the harsh surface environment of Venus, Venus has been under the [[planetary protection]] category two.<ref name=NRC_2006/> This indicates that there is only a remote chance that spacecraft-borne contamination could compromise investigations.