There are traces of a kind of molecule in the atmosphere of Venus. The molecule only produces microbes and human activities on our planet, and smells of decay with other compounds. This discovery made with James Clerk Maxwell and the ALMA telescope pointed out the existence of unknown geological or chemical processes on our neighboring planet, although it did not rule out any possible biological sources.
This Phosphine or phosphine (Its official name) or Phosphorus (PH3) Is a pure, colorless, flammable, toxic, and odorless gas, although it usually smells like garlic or rotten fish when used with other similar compounds. The substance exists in environments such as swamps or feces.
On the earth, apart from the artificially produced phosphorus in industrial processes, only some anaerobic microorganisms produce phosphine. For example, it is used in semiconductor manufacturing to introduce phosphorus into silicon crystals.
But this week, an international team of researchers led by professors Jan Greaves Cardiff University report in the magazine Natural astronomy People who have detected phosphine in unexpected places: Venus atmosphere.
This discovery raises people’s expectations about whether there is some form of life in this gas on our neighboring planet, although the author points out more possibilities:3 It may originate from unknown photochemical or geochemical processes, or is similar to biological production on the earth, due to the existence of life. “
In the earth’s atmosphere (10 parts per trillion on a global scale), the molecule is only related to man-made or microbial activities, while in the solar system, it only exists in the atmosphere. Reduce the atmosphere of giant planets, It occurs in the high-pressure and high-temperature deep atmosphere, and then rises upward through convection.
but, Rocky planetLike Venus, they constitute a barrier to the interior. Phosphine should be quickly destroyed in its highly oxidized outer shell and atmosphere.
A sign of possible life
In fact, PH3 Some people have proposed using it as a biological signature. The detection results may indicate that there is some form of life on these planets. Although many spectral features are strongly absorbed by the Earth’s atmosphere, its observations are very complicated.
To solve this problem, Greaves and his colleagues observed Venus with two telescopes most suitable for recording sub-millimeter radiation: Telescope James Clerk Maxwell And Atacama large millimeter/submillimeter arrays (Alma), respectively in 2017 and 2019.
In this way, they detected the unique spectral characteristics of phosphine and estimated the abundance of 20 parts per billion in the Venus cloud.
In principle, the conditions on the surface of Venus are Hostile to life, But the upper cloud layer is temperate, about 53 to 62 kilometers above the ground.However, the composition of the cloud group is Very acidic In this case, phosphine should also be destroyed soon; but it has appeared.
“Airborne” microorganisms on Venus?
Astronomers have speculated for decades that there may be microorganisms in the high clouds of Venus. These microorganisms will float out of the hot surface but require very high acidity tolerance. Phosphine detection may indicate that this kind of alien “air” life is possible.
The author analyzes different methods of generating PH3Including possible sources on the planet’s surface, volcanic activity, micrometeorites, lightning or chemical processes occurring in clouds. At present, they have not been able to determine what caused the traces of phosphine.
Although they did not completely exclude it in the study, the authors believe that its findings There is no strong evidence of microbial life It only shows that our neighbors are undergoing potentially unknown geological or chemical processes.
The research team pointed out that more observations and models are needed to study the origin of this gas in the atmosphere of Venus, and other spectral characteristics of PH should be sought.3, In addition to illustrating sampling In situ In its clouds and surface, it will allow careful examination of the source of this gas and solve its mysteries.
Jane Graves and so on. “Phosphine gas in the clouds of Venus“. Natural astronomy, September 14, 2020.