How to look for the inhabitants of other planets according to scientists
Astrobiologists propose to search for signs of life on nearby Earth, the planets and their satellites. Ecological niches suitable habitat for microorganisms, there are on Venus and Mars, Europe and Enceladus.
RIA Novosti says about where in the Solar system most likely to meet with extraterrestrial beings.
The Atmosphere Of Venus
Space at the height 51-65 kilometers from the surface of Venus could be habitable, according to British scientists. They found that the temperature there ranges from minus 20 to plus 65 degrees Celsius. The atmosphere consists of water vapor, highly saturated with aerosol of sulfuric acid.
In such circumstances, survive bacteria-the extremophiles that feed on sulfur. For example, the archaea Picrophilus, living in the hot brines of the island of Hokkaido.
On Earth, extremophiles belong to the most lifeless place — hot underground springs, anoxic tanks, permafrost. Some microbes have adapted to feed on inorganic substances, digesting them with the help of solar energy. Cyanobacteria survive at temperatures up to 70 degrees — higher values destroys the chlorophyll in their cells.
A weak magnetic field does not protect Venus from the flow of high energy particles of galactic radiation. Solar flares there is more dangerous than on Earth, whose orbit is farther.
But the atmosphere of «planet of crimson clouds» at times denser than earth’s and it is better to delay radiation. However, the chances to survive on the surface of Venus is still there, according to the researchers.
Archean Nanopusillus acidilobi lives in the highly acidic hot springs of Yellowstone Park (USA). © Photo : Wurch et al. / Nature Communications 2016
Liquid oceans and biosphere may have been on early Venus, but subsequent greenhouse effect turned it into a dry sterile desert. It is unlikely that life survived beneath the surface, in the soil. Only where it can warm — among the clouds high in the atmosphere.
For example, the Mesophilic bacterium Deinococcus radiodurans survive even when irradiated in ten kilogray. And hyperthermophily of the archaea Thermococcus gammatolerans propagated at 88 degrees and withstands a radiation dose in three kilogray.
The underground ocean of Mars
Many scientists believe that Mars and the Earth three to four billion years ago was similar and equally rich in water. American geologist Timothy Parker saw in the pictures of the «Viking» contact zone of land and sea around the Northern Wasteland (Vastitas Borealis) is a vast lowland in the North pole of the planet.
Judging by the terrain, the Martian ocean was a periodically replenished with moisture Everglades. It is estimated that there could accumulate about 2,3×107 cubic kilometers of water. A third of it evaporated, one-third went to education polar ice cap, and another third could be saved in the form of a layer of ice under the ground.
Unlike the Earth, the climate of early Mars was cold. However, the Red planet could be the cradle of life, believe scientists from NASA. The discovery in the Gale crater sediments, similar to those formed in the geysers, extremely inspired supporters of the hypothesis of panspermia, in which life on Earth has brought the comet.
Fungus of the order Chaetothyriales, are found on the stones of the University of the valley © Photo : CDC/Sherry Brinkman
The drying oceans and lakes does not mean the disappearance of life. It is known that some of its forms is able to extract moisture from the atmosphere or soil. In addition, on Mars five million years ago were the conditions suitable for life. Then the inclination of the orbit of the planet was 45 degrees — this means that the pole received two times more solar heat than it is now. About the same as the polar regions of the Earth.
The polar caps of Mars are melting not now, but five million years ago, they were like what is now Antarctica. The closest analogue of the South pole of Mars — a dry high-mountain permafrost of University valley in the South of the continent. They are similar to those detected by the apparatus Phoenix on the red planet.
In the permafrost of University valley, which does not melt even in summer, found microorganisms. Scientists have identified the DNA of several strains of bacteria, archaea and lower fungi. All of them were dormant or had died. In the laboratory, several species managed to awaken to life.
The icy ocean on the orbit of Saturn
The sixth largest moon of Saturn, Enceladus, is covered with ice with a thickness of 40 kilometers. In 2011, the unit «Cassini» recorded at the South pole of Enceladus jetting water, sodium chloride, ammonia and carbon dioxide. This led the scientists to assume that the ice is hiding a salty ocean.
Then, the satellite has an internal heat source. According to calculations, the water temperature in the ocean may be 26 degrees Celsius, although on the surface, or minus 170.
Colonies of the cyanobacterium Trichodesmium thiebautii color of the tropical water red. But the red stripes are found along the faults on the icy moon of Jupiter — Europe © Photo : FWC Fish and Wildlife Research Institute
The warm, salty ocean — a good place to live. From cosmic radiation and protects the icy shell. However, he doesn’t miss the sunlight, but it is not critical, because many groups of microbes live in the dark. For example, organotrophic bacteria that exist due to the decomposition of organic matter, or hemotrofy using the energy from oxidation-reduction reactions.
Conditions of Enceladus is close to the subglacial lakes of Antarctica. The most accurate analogue of the considered relict lake Vostok under four-kilometer layer of ice. However, living organisms it has not yet been found.
But encouraged by the Untersee lake. The glacier above it never melts and conceded only five percent light. Despite this, there is a high level of microbial methane to the award, and at the bottom revealed a powerful bacterial mats and stromatolites.