Meteorites – pieces of large cosmic bodies brought to our planet by a long arm of coincidence – attract attention of microbiologists for a long time. Scientists from RAS Lithosphere Institute (S.I. Zhmur) and RAS Microbiology Institute (professor V.M. Gorlenko) in cooperation with RAS Paleontology Institute (RAS corresponding member A.Yu. Rosanov) have examined several meteorites, the largest of which are called Allende (Mexico, 1969), Murchison (Australia, 1962) and Efremovka (Kazakhstan, 1962). All examined meteorites are stones. They have little iron and much carbon. These cosmic bodies have most probably traveled here from asteroid belt of Solar system. When a meteorite penetrates Earth’s atmosphere, its surface melts and thus forms a protecting crust, which protects internal organic matter from burning. Carbonic stony meteorites often contain complex carbohydrates: purines, pyrimidines, fatty acids and even amino acids. Scientists have found traces of life in every examined meteorite.
 

The scientists have examined meteorite cleavages by means of scanning electron microscope and found structures looking like pieces of microorganisms – pellet and filamentary formations and fragments of chains. The scientists suggest these structures to be cyanobacteria (blue-green algae), filamentous fungi and actinomycetes colony remains. The reason for such hypothesis, according to V.M. Gorlenko, is objects’ size and shape, which are comparable with size of modern microorganisms and their petrified remains that had been found in Earth’s ancient rocks. Traces of microorganisms have been found long ago in ancient terrestrial rocks with high carbon content – 2.5-bilion year old oil and black shales. And the most ancient microorganisms’ traces had been found in marine rocks – petrified cyanobacterial communities. Their age is 3.5-3.7 billion years. In these rocks, as well as in meteorites, organic matter in substituted with minerals, usually calcium or silicon.
 

Microorganism traces can also be found in volcanic rocks aged 1.7 billion years. Scientists have detected cell wall fragments, cyanobacteria cover remains and something like cytoplasm of coarse structure on ultrathin sections of volcanites. Such microorganisms are thought to live under high temperature conditions. Cyanobacteria are able to live under extreme conditions: in thermal springs, saline and alkaline waters and even on glaciers. Mr. Gorlenko says that cyanobacterial communities are very conservative and appear to be the most ancient biosystem, coming from almost the very beginning in an unchanged state.
 

Scientists admit the possibility of life traces found in meteorites. But there exist two alternative hypotheses. First, microorganisms could enter meteorites on Earth. But researchers think that it’s not so. There are too many traces of living matter per meteorite volume unit, and it’s partly substituted by minerals, which usually takes hundreds of years. Another hypothesis is that found “organized elements” are the result of chemical synthesis and have nothing to deal with remains of formerly alive microorganisms. This theory looks reasonable, however experts say that extremely high temperature is needed to synthesize such structures. If so, it is hard to explain the presence of low-temperature minerals and organic matter in the examined meteorites.
 

If there are real traces of microorganisms in the meteorites, then we can say that life appeared in the Solar system 4.5-4.6 billion years ago, when Earth crust still hasn’t formed. Mr. Gorlenko thinks that the fact of seeing microbial communities instead of individual cells is very important. Individual cells entering new habitat, i.e. traveling to the Earth from another planet, should have inevitably died, and community have had a chance to survive.
 

The science has acknowledged extraterrestrial life existence, though it gives no explanation for it appearing in the Universe. But may be V.I. Vernadsky was right, when he said that living comes from the living only, thus life in the Universe is eternal.