What should have been the physical conditions on the Earth, the Sun and in the solar system for the formation of the biosphere on our planet? What galactic factors influenced the origin of life? Is there life beyond the Earth? These and other scientific questions within the framework of the educational festival Science Bar Hopping were answered by the candidate of physical and mathematical sciences, senior researcher of the Department of Solar Physics and Solar-Terrestrial Relations of the Institute of Terrestrial Magnetism and Radio Wave Propagation. N. V. Pushkova RAS Maria Ragulskaya.
“In the scientific community, the dominant point of view is that life is primarily a global phenomenon. And if we approach the issue of its reconstruction, without considering only the anthropogenic principle, then life can be created on many planets, since there are no physical and chemical restrictions in this regard,”the expert said.
Solar activity and life
The biosphere of the Earth processes such an amount of solar energy, which exceeds the energy of tectonic and volcanic processes by 30 times and is practically equal to all thermal energy from the interior of the Earth. In the eleven-year period of solar activity change, the contribution of the Sun to the development of biosystems and to the climate is 10%. In a 250-year period, this contribution grows to 70%.
Our life is chiral
Life is carbon and water based. This complex structure requires a chemical base and solvent. The genetic code of earthly life -not the only biochemically possible. Liquid ammonia and sulfuric acid are suitable as a solvent, and boron or nitrogen bonds at high temperatures will replace carbon. Man consists of molecules of a certain chirality, also non-exclusive. Chirality is the property of a molecule not to combine in space with its mirror image. “Chirality is like gloves - left and right. If the molecule is twisted in one direction, then no movement in space to the other can turn it over. It is incorrect to say that life processes cannot be realized in the Universe, as on Earth, but twisted in the opposite direction. It is not known for what reason only one option has come true on our planet. These scientific issues are dealt with by scientists who study the origin of life. That is, it is not enough to assemble a molecule, it is necessary to provide a process,separating right from left and accumulating a suitable option for life. And, paradoxically, such a process was provided to us by the young Sun with its radiation - said the expert.
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Where to look for life?
The early period of the development of life on Earth was different from the modern period: the chemical composition of the oceans, the atmosphere, temperature, the location of the planets and active meteorite bombardment. The search for the origin of life should begin from the time when the chemical composition of the Universe became approximately the same as it is now - this is 7.8 billion years ago. During this period, the primary vital heavy elements appeared - carbon and water. These elements of our body are the remains of burned-out stars. We are all made of stellar matter. That is, for about half of their lives, the Sun, Earth and the Solar System were in completely different conditions, and not in those to which mankind is accustomed. Reliable life on Earth - the one found in fossils - 3.8-4 billion years ago. Scientists cannot say that there was no life before,since practically no rocks have survived older than this age. More ancient information can be obtained from meteorites.
How was the solar system born?
The solar system took about 900 million years to form. She was born in a dense star cluster of similar star systems. They appeared after supernova explosions. Perhaps the fall of meteorites was due to the fact that the systems diverged and exchanged meteorite matter.
Galactic life
In the galactic interstellar medium, many complex organic substances have been found that make up living organisms. Galactic clouds, through which cosmic rays pass, are a huge source of organic matter. Modern scientists have discovered more than 200 such substances. Scientists have a difficult task - to decipher this data.
Early Mars - an oasis for life
On early Mars, for the first half a billion years, there were all the conditions for the origin and development of life, while on Earth there were no such processes. The young planet had oceans with a large supply of water, an atmosphere and a warm climate. However, Mars is a small planet and far from the Sun. There is also such a thing as "solar wind" - a stream of ionized particles from the solar corona. This stream ripped off the atmosphere of Mars. Most of the meteorites that reach us are Martian. If there was life on the planet, then it moved from Mars to Earth, and not vice versa.
Sun: then and now
The early Sun and the modern Sun are not equal. The Sun had many more sunspots, and its luminosity was much lower - 70% of the current state. The star gradually flared up (to date, the luminosity has increased by one and a half times), but at the same time the solar flares were very active. The mass of the early Sun is up to 103%, the rotation period is from 6 to 10 days. The intensity of the ongoing processes was a hundred times higher than the current level.
Searching for a planet to live
For survival, the biosphere needs: liquid water on a space object for a long geological period, organic compounds, energy sources for biochemical processes and a protective shell. The goal of scientists is to find places that are protected from radiation and where water could be stored. They don't look for life in a mono-environment. Scientists believe that life is formed due to the quintessence of three phases: liquid, gaseous and solid.
“There is a big debate between biologists and geologists about where space missions can be landed to search for the biosphere on Mars. Geologists claim that the most ancient rocks. Biologists, on the other hand, believe that with the radiation that was billions of years, these rocks are gone. Biologists prove that Mars still has a quasiperiodic type of atmosphere. From time to time, Mars changes the axis of the planet, and its polar caps melt. Perhaps once every 120 thousand years, water appears on Mars for several weeks. Terrestrial organisms can survive 120 thousand years in suspended animation. If water appears on Mars once every 120 thousand years, several weeks will be enough for the organisms to revive, produce a life cycle, leave offspring and then wait for the next 120 thousand years,”the expert said.
They are looking for life on Venus. Under the conditions of pressure and temperature of Venus, instead of carbon, chemical compounds based on nitrogen can be obtained, and the supercritical fluid of carbon dioxide will act as water. Scientists can write reactions theoretically, but they cannot test them under terrestrial conditions. It is necessary to build a plant with the size of several planets. The land is small for laboratories for the production of such substances. But in space, these experiments are quite possible.
As of 2019-10-03, the existence of 4011 exoplanets in 2996 planetary systems was reliably confirmed. Among them, the terrestrial type - from 5%.
The main limiting factor in the search for life is radiation from the parent star or gas giant planets. The biosphere can adapt to anything: withstand high temperatures, find chemicals and energy sources. However, the biosphere is unable to withstand the strong impact of radiation rays.
“Terrestrial life is not the only biochemically possible form. The cradle of life can be both molecular galactic disks and exoplanets, and volcanoes and oceans of the Earth, Mars and minor planets and giant planets. So, will humanity be able to identify such a life if it accidentally finds it in its space missions?”Concluded Maria Ragulskaya.
