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SETI: The exploring, understanding, and explaining of the origin, nature, and prevalence of life in the universe



Introduction:
Ever since 1984, the SETI institute has patrolled the skies in search of alien life. They also search to understand the beginning of life on earth and to learn “our place among the stars.” It is comprised of three facilities, The Carl Sagan Center for the study of life in the universe, The Center for SETI research, and the Center for Education and Public Outreach. SETI is a non-profit organization insuring that scientific knowledge of the study of life in the universe is past on.


NAN7172.jpgConditions for Life




So what's the deal with conditions for life these days, but seriously folks, conditions for life is the requirement for there to be certain conditions on a planet to support life as we know it. One condition for life is the presence of liquid water. Life as we know it requires water to continue to exist. Another condition for life is an abundance of biogenic elements such as atomics carbon, hydrogen, oxygen, nitrogen, the list goes on, but seriously folks. We have to have these elements to live. A source of energy is also necessary to life. Here on Earth, we have the sun which is the closest star to us. Every form of life as we know it requires a source of energy that provides a source of radiation or photochemical products. The final condition for life is a stable and protective environment. The atmosphere holds in oxygen and protects us from the UV rays of the sun.

Chemical Evolution
Chemical evolution is essentially the process by which increasingly complex elements, molecules and compounds developed from the simpler chemical elements that were created in the Big Bang. Recent astronomical observations have discovered that chemical evolution has even led to the synthesis of complex organic molecules in space, a discovery that could have serious implications on current theories of how life developed.

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The chemical history of the universe began with the generation of simple chemicals in the Big Bang. Hydrogen and helium, the two lightest chemical elements, were and still are the most abundant elements in the universe. All stars derive their energy through the nuclear fusion of these light elements into heavier elements. Once stars have exhausted their energy supply by converting all of their hydrogen to helium, the star cools and contracts, with the increased pressure from the contraction initiating the fusion of helium to form carbon.

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The Miller and Urey experiment simulated hypothetical conditions that were thought at the present time to be on early planet Earth. Mostly the experiment tested a Soviet scientist Alexander Oparin who hypothesized that conditions on early Earth favored chemical reactions that synthesized early compounds. It is considered by many to be the classic experiment to the origins of life. The experiment used methane, water, hydrogen, and ammonia. The chemicals were sealed inside glass flasks and tubes that were connected in a loop. The water was heated and they fired electrodes through the water to simulate lightning. The water would then condense and the cycle would begin again. At the end of one week of continued cycling, they found that 15% of the carbon had become organic compounds. 2% of it became amino acids. This experiment represents the early atmosphere of Earth and how organic reactions are favored in the atmosphere.

How does SETI work?

SETI is a tool we use to search for intelligence on other planets and moons. Most SETI organizations search for radio signals. Radio signals can carry messages, just like they carry sound to radios. Radio signals that carry messages have special patterns. SETI scientists look for these special patterns in radio signals. Giant telescopes also look for information from space. A smaller, but growing number of organizations search for light signals.

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Earth's first life forms
It is estimated that the first life forms on earth were primitive, one-celled creatures that appeared about 3 billion years ago. That's pret-
a_guide_to_the_orders_of_trilobites.jpgty much all there was for about the next two billion years. Then suddenly those single celled organisms began to evolve into multicellular organisms. Then an unprecedented profusion of life in incredibly complex forms began to fill the oceans. Some crawled from the seas and took residence on land, perhaps to escape predators in the ocean. A cascading chain of new and increasingly differentiated forms of life appeared all over the planet, only to be virtually annihilated by an unexplained mass extinction. It would be the first of several mass extinctions in Earth's history.


Evidence of life
In Feburary of 2003 the SETI program received strange radio signals. Three of the signals had faded away but one of them had growAliens1.gifn stronger. The scientists were baffled because the part of the galaxy that had emitted the signal was unexplored. The signal was picked up by a SETI telescope in Puerto Rico. Nevertheless, there is also a good chance the signal is from a never-seen-before natural phenomenon. For example, an unexplained pulsed radio signal, thought to be artificial in 1967, turned out to be the first ever sighting of a pulsar.






Radial Velocity: Discovering Extrasolar planets, one step at a time

The vast majority of planetary detections so far has been achieved using the radial-velocity technique from ground-based telescopes. The method requires the light from a star to be passed through a prism and split into a spectrum.
When the spectrum is magnified, straight black lines can be seen on the colors. These spectral lines correspond to thdoppler.jpge wavelengths of light that have been absorbed by chemicals on the surface of the star from which the light came from. Every element and molecule makes its own chemical fingerprint through unique spectral lines at different wavelengths. These provide an indication of the amount of that element in the object and under what conditions such as temperature and pressure.
Studying these lines can show which stars have large planets around them. As the planet orbits the star, gravity pulls on it, forcing the star into a small orbit, or wobble. It makes it look like the star is spinning around a point in space. The star will sometimes be spinning towards Earth and at other times spinning away.
When the star moves towards Earth, the wavelengths of the spectral lines in the light it emits move towards the blue end of the spectrum. When the star travels away from Earth, the opposite happens, and the wavelengths are moved towards the red part of the spectrum. Astronomers therefore look for stars where the spectral lines are moving back and forth, since these must be the ones with planets in orbit around them. By measuring the amount of movement with time, the mass of the planet and its orbit can be determined.


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So in conclusion SETI is a very helpful tool for discovering life and extrasolar planets. It goes farther than that however, they go so far as to explain the origins of life on Earth. The philosophy in this case is a better understanding of our world will help us discover other life. Understanding what we need to survive will help us realize what other life forms might or might not need to survive. Understanding our early planet will help us understand planets similar to ours elsewhere in the galaxy. There have been small signs of other life but all we can do now is keep trying and hope it pays off.

SOURCES
http://www.lifeinuniverse.org/noflash/Conditions-04-02.html
http://science.jrank.org/pages/1387/Chemical-Evolution.html
http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/miller.html
http://www.daviddarling.info/encyclopedia/M/MillerUreyexp.html
http://www.seti.org/Page.aspx?pid=1241
http://www.actionbioscience.org/newfrontiers/jeffares_poole.html
http://www.geocities.com/capecanaveral/lab/2948/orgel.html
http://www.newscientist.com/article/dn9943
http://www.daviddarling.info/encyclopedia/R/radial_velocity_method.html
http://ww2010.atmos.uiuc.edu/(Gh)/guides/rs/rad/basics/rvel.rxml