"Life is not about what we know, but what we don't know, craving the unthinkable makes it so amazing, that is worth dying for." Doru Indrei
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Life In The Universe

                             Suppose now that somewhere, far, far away, there is a planet that harbors life. Could we somehow detect it? Could we read in the newspapers over the coming decades titles like: "Alien life was discovered"? 
                 The most obvious way to discover alien life would be sending a spatial probe, collecting samples from the planet chosen by us. Unfortunately this has a blemish way. With our tehnology we can do expeditions only in our solar system. We have some chance to discover life-forms on Mars, Titan or Europa. Expeditions that are underway or in the final phase of preparations will bring answers over a while. Of course, we are likely to find life in other places in the Solar System  too, but increasing the chance of discovering intelligent life ,we gotta get used to the idea to look in other star systems, to find life in the universe.

                No matter how optimistic should we be, we can not hope that we will very soon create those technologies that will allow us to get out and beyond our solar system. It is certain that will be made ​​once, when we better understand the fabric of space and time. Until then we should look for some ways that will allow us from here, from Earth, to identify those planets where life evolved. 
It may seem surprising to many of you, but this search has already begun, by identifying the first extrasolar planets, to find life in the universe.
               This discovery allowed us to say that planetary systems are not rare events in the universe. Followed, in November 2001, announcing an epochal discovery: it was first discovered an extrasolar planet with atmosphere. It's planet HD 209458, the discovery was detailed in Science and Technology 1/2-2002. Moreover, a brief analysis could be made of the composition of the atmosphere. Could this kind of discovery help to identify distant life-planets? And life in the universe?

               Two important missions, one organized by NASA, with it's Kepler Space Telescope and the other by ESA, is about Darwin Space Telescope.The NASA spacecraft was launched on March 7, 2009 with a planned mission lifetime of at least 3.5 years, designed to discover Earth-like planets orbiting other stars. Here is a very important step in detection of extraterrestrial life

            First, the mere discovery of such a planet, to a right distance from the right star, could easily tell us the possibility that there life could be sheltered. But to science this is not enough. Evidence is needed. If there is life on a planet, the atmosphere should signal its presence. Even the air you exhale, the moment you read this article, gives us information on your presence. It contains more carbon dioxide than in the normal atmosphere. We know that someone is the room, by simply analyzing the air in the given room.
           We could tell if there are "creatures" by changes that are made in air composition inside. 

                We can also undertake research on a planetary scale, in the hope that we can find signs of life on a certain planet. But in such a situation, things are complicated. As a fact, the only possible form of life is based on liquid water and carbon. It is possible that this is a limitation of the scientific imagination (which, unlike other kinds of "imagination", needs a solid base).  

               We, scientists, have few limitations in this regard and therefore we can say that there might be other life-forms that have no connection with what we know so far.Life in the universe out there can be very bizarre.
               But we can not go too far, because we can not remove too much of what we know. We added this paragraph a statement that belongs to a scientist at NASA. David Des Marais is a researcher at Ames Research Center, said that "we must consider to what extent alien biology might be different from ours, especially when it comes to macromolecules." (This is why silicon-based life could be taken into account although, in this grouping, have made ​​strong arguments against it.)
               Let us return for a short while to the example that I gave earlier. Say that we can identify the presence of people in a room just by analyzing the composition of air inside. A supplement of CO2 would be sufficient and satisfactory proof. A similar path should follow when looking for signs of life in the universe on other planets. We depart from the assumption that living organisms possess a metabolism. Simplified speaking, they take certain substances from the environment and eliminate others. The utmost importance, is the presence of the oxygen. When referring to an extrasolar planet, will have to consider an entire atmosphere, not a small area of it. Therefore the oxygen would be the best indicator of life. It is a highly reactive element which quickly combines with existing chemical elements on the surface or in the planet's atmosphere. 

             Free oxygen can not survive long in the atmosphere of a planet, as long as it is not generated by a geological or biological process. The same thing we can say for terrestrial oxygen. It is the result of metabolic processes during photosynthesis, or, if you will, it is the result of "pollution" from the plants. Carl Sagan noted in 1997 that "high concentration of oxygen in the Earth's atmosphere could be very difficult to explain in the absence of life." 

               Here is the first criterion that could help to identify the existence of life in the universe on a distant planet, thousands of light years from Earth. Sure, now I have to tell you how to identify the oxygen in the atmosphere of a distant planet. Principle is not complicated and was already used to detect extrasolar planets with atmosphere, as was the case of HD 2094. 
              Practical we only have to follow the spectrum of the target star, seeking dark lines that are specific elements that absorb light of the star on certain frequencies. We make this observation for long periods, carefully watching the periodic appearance and disappearance of additional lines, it indicate a planet passing in front of the star disc. These lines indicates the presence of a planet periodically passing in front of the star.

             In the next stage will see whose elements correspond to absorption lines. If we identify the oxygen, we can move forward. We will make more precise measurements , we determine the mass and distance of the planet from the central star. If the values ​​obtained will overlap with those considered by us to be favorable for life, than we can announce the newspapers that (probably) we have discovered a planet that harbors life.
            Perhaps you don't like our eternal distressing uncertainty, our repeated lack of safety. So is science. Additional evidence is needed to confirm their initial ones.

            Where can we find them? If we can not go fast on the planet assumed to be a shelter for life, we call the same method indicated above. We will look more carefully in search of another gas that should not be there. The gas that we refer now is already an indication as to the existence of life on a celestial body, apparently close to our eyes, it's Mars.  

             Mars Express Probe has detected traces of methane in the Martian atmosphere, which could have indicate the existence of primitive life-forms on the Red Planet. Why would methane gas be an indicator for life? In fact it is not as chemically reactive as oxygen and, therefore, could survive long and hard in an atmosphere that was generated by the biochemical pathways. Methane is not very reactive. But methane has another interesting property for us: it is unstable. Its chemical bonds break easily under the action of cosmic radiation, so it will decompose quickly enough (for Mars let's say 400,000 years)
            To continue our demonstration about life in the universe, we will add that methane is an important metabolic product resulting from metabolism of certain bacteria that break down dead organisms .
That is why, the very moment we find, simultaneously, the atmosphere of extrasolar planets, both oxygen and methane, as we move from "very likely" to "almost certainly" when will communicate to world the news "life on another planet found". 
            Recent discoveries brought in full light a lot of planets that have atmosphere and even liquid water, but their distances ranging between 40 and 200 ly and even more, and right now this is a problem for us. 
           Furthermore, the future? The future is as exciting as it gets. It takes by surprising in a good way, especially when it comes to science. Life in the universe will eventually emerge. But the precise location, we can't tell yet. However, whenever the event will occur, we must prepare our minds to accept things that right now comes with the word "unimaginable"...

            by "environment clean generations"


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