When the Cassini spacecraft (as of October 15, 1997) within 175 km (109 miles) from Enceladus flew in July 2005 assumed everything had to be discarded on the moon of Saturn known. With the unexpected discovery of a huge geyser of water and the strong presence of water vapor in its atmosphere, the satellites are thought to be small and "dead" (ie no geological activity) is the best hope for finding extraterrestrial life has been date. Even if everything isto support the existence of life - water, "an appropriate heat source right chemical nutrients and precise environmental conditions [that] carry out the chemical reactions necessary ..." [1], Dr. Robert Brown, a planetary scientist at the University System of Arizona and a senior scientist working on the Cassini project, said that "a major conference in Vienna, Austria, [that] contains Enceladus ... ingredients for life. "[2]
History andDescription:
Enceladus, August 28, 1789 by German born English astronomer Sir William Herschel (1738-1822), known for his discovery of Uranus discovered known, is the sixth largest moon of Saturn, with an average diameter of 504 km (313 miles) , about seven times smaller than Earth's moon. And 'orbit of Saturn "at a distance 238,000 km (147,886 miles) from the center of the planet and 180,000 kilometers (111,847 miles) from the surface, between the orbits of Mimas and Tethys(Two other moons of Saturn), tidally locked "... keeping one face pointed to Saturn", and excludes any revolution in 32.9 hours [3].
Based on results of Cassini Enceladus is composed of a core with a higher percentage of iron (FE) and silicates (silicon compound (Si) and oxygen (O), one or more metals and possibly hydrogen (H)) that may have experienced more heat of radioactive decay, as the interior of Saturn's icy other mediumMoons. Enceladus has a slight gravitational field, which has a density of 1.61 grams per cubic centimeter.
Although known for almost two centuries, there are Enceladus, "an exterior of only three bodies of the solar system (with Jupiter's moon, Io and Neptune's moon Triton) where active eruptions have been observed" was a grain for the program Voyager. Voyager when I flew 202,000 kilometers (125,517 miles) of Enceladus November 12, 1980, revealed "ahighly reflective surface, with no impact craters revealed [reference] a young surface, "Voyager II, which flew 87,010 kilometers (54,065 miles) of Enceladus, August 26, 1981, a surface that varies is the oldest and some of the -. craters (average region-to-high northern latitudes), while others easily crater (near the equator) and the rest is usually smoother and younger [4].
On February 17, March 9 and July 14, 2005 flyby of Enceladus, Cassini revealed the surface 'much closer. "Smooth Levels dissolved in a relatively crater-free regions with many small ridges and steep slopes filled. ... A number of fractures (may be warm by building pressure on the temperature difference between the surface of the moon and the icy surface and causes the external environment) were in the older, cratered place ... and some other area youths were discovered near the ... ... as [moon] South Pole... [Includes] a fascinating dark spots, 125 and 750 meters (410 and 2461 m) wide, parallel to the fractures are narrow [and is believed to be] filled the collapse was "thick blue ice. Cassini moon again the plain and smooth ( Sarandib Diyar Planitia Planitia s) leading to estimates that this area is between the ages of 170000000-3700000000 years, and the area in front of Saturn, according to the "should-crossing sets are covered in numerous cross-depressions and ridges, "and the geologically active south pole that adds the presence of an active geyser whose glittering waters of Saturn's E ring and revealed a" unique region tectonically-deformed [estimated age from 1 to 10 years out] as far north as latitude 60 degrees south ... covered with tectonic fractures including four corners and these fractures [on both sides by ridges called "tiger stripes", covered with ice, and also limitedRocks between 10 and 100 meters (33 to 328 feet) wide, which] appear to be less than 1000 years. "[5]
The discovery of cryovolcanism ("outbreak of water and / or other liquids or steam-volatile phase, together with fragments of gas based on the solid surface of a planet or moon due to internal heating") [6] at Enceladus' south pole , where a geyser gushing water and other volatile silicate rock place, together with the presence of a volatileAtmosphere (thicker around the south pole), which consists mainly of water vapor (H2O) (91%) with small amounts of molecular nitrogen (N) (4%), carbon dioxide (CO2) (3.2%) and methane (CH4) (1.7%) represents the best hope for life to exist anywhere above or below the surface of the moon, despite an average surface temperature of about -325 degrees Fahrenheit.
Water Enceladus' geysers:
When Cassini flew by Enceladus in November 2005 confirmed the January 16, 2005The discovery of a number of geysers, like jets of water and ice particles (the composition was determined during the July 2005 flyby, Cassini flew directly through if the flag), and that numbers more fractures or openings ("tiger stripes ") in the lunar crust. A spring rose as high as 500 km (311 miles), driven by pressure chambers under the surface, temperature differences, the weaker gravity of the moon - about 12 times weaker than Earth and a halfGravitational force, and to a certain degree of attraction of Saturn.
Based on "the combined analysis of mass spectrometry data of images and magnetosphere," is that Enceladus' sources of water and ice particles are "sub-surface pressure rooms [is less than 100 meters (328 feet) below probably frozen surface of the moon, which consist of pure water near 26 ° -32 ° Fahrenheit first expulsion] heated, similar to geysers onThe earth. "[7] A further confirmation that the water is liquid below the surface has been the analysis of Cassini carried out on the ice for the" tiger stripe "fractures." The ice was amorphous and almost no crater, suggesting that ran recently. "[8]
Moreover, the absence of ammonia (NH3), which can serve as an antifreeze for the water, it is likely that the lunar surface under the water heated by solar tides (frictional heatBending forces or displacement caused by the gravitational pull of Saturn, 2:1 "means motion orbital resonance with Dione," [9] a nearby moon, which means that two orbits of Saturn's Enceladus does for each of Dione, and a lesser extent in the attraction of the Tethys, another cause close to the Moon) and radiogenic (by radioactivity or processing radioactive) sources, as a pole Enceladus' south, the temperature is about -177 degrees Fahrenheit cold -298 °of -325 degrees Fahrenheit for most of the rest of the lunar surface and because the particles of water and ice must "have a certain density ... that implies surprisingly warm temperatures," will be performed in air. [10] The difference is too large to be explained by solar systems in the icy surface of Enceladus' reflects more than 90% of solar energy in space weak again. According to the Moon "has the highest albedo (the ratio of reflected light) of a body inSolar System "with a measure of> 0.9 [11].
According to research presented at the European Geosciences Union (EGU) conference in April 2006, the core Enceladus' of molten rock was as hot as 2,060 degrees Fahrenheit to further strengthen the theory that the moon is geologically active sources powered by tidal and radiogenic.
Lifeforms probably on Enceladus
If life can be found on Enceladus, is probably the form of microbes that may exist to be extremely simplein rough, seemingly inhospitable environments, as long as the chemical nutrients are biomolecules such as amino acids, a source of energy and liquid water is present, its obviously the case when it comes to pressure rooms that provide geothermal heating to the moon.
The case of possible extraterrestrial life:
Ingredients for Life:
Two key ingredients for life are water (H2O) and a source of energy (even if it is found to be unnecessary for somecryophiles chemosynthetic), fuel and support the metabolism of a body. Both are Eceladus. Tanks mountain of liquid water beneath the surface of the moon performed while about 99.9% of the topography is covered with water (H2O) constantly shooting geysers of ice, which will stimulate as particles of ice and snow updates. At the same time, the jets hydrothermal power of geysers of Enceladus' are an ideal habitat for microorganisms in the same way, the deep sea andYellowstone National Park to hydrothermal vents on Earth.
A third component is nitrogen, which is on Enceladus and the atmosphere. "Nitrogen is an essential amino acid (" organic compounds with an amino group (NH2), a carboxyl group (COOH), and each of the various side groups, in particular one of the 20 compounds that have the basic formula NH2CHRCOOH, and that more peptide bonds to form proteins or function as this chemicalMessengers and as intermediates in the metabolism of complex organic molecules in all living cells and viruses found, is composed of purines, pyrimidines, carbohydrates, and phosphoric acid "), commonly called the building blocks of life) and nucleic acids (called". Acids Nucleic form of DNA and RNA control cellular function and heredity ") [12].
A fourth ingredient is the presence of organic compounds, substances composed of carbon (C), the signature element of life. Based onCassini flyby, the existence of simple organic compounds along the "strip tigre" fractures, and the fountains gush of water and ice crystals from the geysers were discovered moon. Small amounts of methane (CH4), carbon dioxide (CO2) and propane (C3H8) have been discovered in the springs, while small amounts of carbon dioxide (CO2) and methane (CH4) into the atmosphere of Enceladus' were found. In addition, Cassini has also detected the presence of ethane (C2H6) andEthylene (C2H4), two other organic compounds.
A fifth ingredient is the existence of a kind "basis for complex chemistry." [13] The view of scientific theories about the beginning of life on Earth, as a chemical does not reach the body for space elsewhere. (Resulting in organic compounds such as amino acids from an "organic soup") in the two "primordial soup" and "metabolism first" (which appeared in the lives of young peopleMolecules, even small RNA, which "eats, carbon monoxide (CO) and sale of methane gas (CH4) and acetate (CH3COO)" recently strengthened by the discovery of Methanosarcina acetivorans, a marine microbe, [14] with only " two very simple proteins "for chemosynthesis for their metabolic needs) theories were the basis for the beginning of life on earth is not insurmountable great, especially because life is born in difficult conditions, when the earthAtmosphere consists primarily of toxic substances such as ammonia (NH3), carbon dioxide (CO2), methane (CH4) and water vapor.
Life expectancy can also be improved, as Enceladus has an intense radiation field and the reduced effectiveness of the sun's damaging ultraviolet (UV) due to lack of time (to reach more), the distance (1427000000 km or 886 million miles are from the Sun) and shield (part of the lunar surface of Saturn because of its protectedsynchronous rotation) factors.
Cryophiles
Lives and fossilized cryophilic (cold-loving) microbes in Arctic ice environments where temperatures up to -90 degrees Fahrenheit (Greenland and northern Siberia) can drop below -125 degrees Fahrenheit (Antarctica) has found. They also found that the volcano is Sverrefjell Svalbard, an archipelago north of Norway, which would be "no living organisms have been provided [to exist after] are adaptedextreme cold conditions. "[15]
Examples include a moss, "which remained in existence, while at rest frozen for 40,000 years in the permafrost of the Kolyma lowland in the north-east of Siberia" covered [16] moss with orange sheets of cyanobacteria blacks "were found in growth" Matanuska Glacier on the ice in Alaska "and actinomycetes (" wire-or rod-shaped microorganisms ... [that] resemble bacteria and fungi ") and the metabolism of othervarious microbes found in samples of ancient ice from Beacon Valley, Antarctica and other local Arctic recovered. [17]
The recent discovery of "a new species of polychaete worms (also known as pink" ice worms ", which is about 1 to 2 cm in length) found that live on the exposed surface of methane (CH4) gas hydrate mound [s] "in cold water deep below the ocean surface are another positive sign. [18] However, the greatest encouragement from the discovery ofcryophiles chemosynthetic requiring no energy source for metabolism. Instead of such a source will receive, only those energy bodies' chemical reactions between rock and water (H2O). " [19]
Thermophilic
Microbes living and fossils were found in geothermal environments or geologically active. An example is the existence of chemosynthetic microbes thermophiles (thermophilic) Norris Geyser Basin in Yellowstone, where temperatures constantly presentgreater than 158 degrees Fahrenheit and photosynthesis can not occur. Consequently, they use hydrogen (H2) to operate for their metabolism. This is particularly encouraging as hydrogen (H) is an important component of water (H2O) are 'and why the sun geysers of Enceladus' surface of Enceladus is probably not sufficient for photosynthesis.
In addition, the use chemosynthetic, thermophilic or hyperthermophilic (extreme thermophilic) bacteria, hydrogen sulfide (H2S) for the metabolic functions(Eg bacterium Aquifex aeolicus) and prokaryotic bacteria and cyanobacteria, together with larger organisms such as giant tube worms (Rifita pachyptila), giant clams (Caliptogena) and mussels), were also the air vents deep geothermal groundwater, where temperatures can reach 716 º Fahrenheit, and sunlight can not penetrate.
When it comes to bacteria Aquifex aeolicus, its requirements are very simple. These thermophilic microorganisms "needs nothing more than hydrogen(H), oxygen (O), carbon dioxide for growth (CO2) and mineral salts "[20] improves the possibility of chemosynthetic organisms or similar-type of Enceladus, exist primarily in its geothermal pressure chambers under the surface.
Extremophiles other
Along with thermophiles and extremophiles cryophilic (organisms that thrive in harsh environments "not realistic" environments), is also a third form - the life that lives in an anaerobic non-oxygen environment under theEarth's crust. Their existence has continued to improve the odds that extraterrestrial life may exist on Enceladus, mainly because the habitat most likely for such a life can be under the surface of Saturn's moon.
"Lunar" Microbes
Perhaps the most fascinating example of the possibility of life on Enceladus points is the proven fact that microbes can survive exposure to the rigors of space. If the probe Surveyor 3 landed on the Moon (Earth's Moon) toApril 20, 1967, was inhabited by an error of between 50 and 100 bacteria (Streptococcus mitis), which survives "to start, the space vacuum, 3 years of exposure to radiation, frozen at an average temperature of only 20 degrees above absolute zero (-453 degrees Fahrenheit), and no source of nutrients, water and energy. "[21] These organisms were still alive when the camera contaminated by Surveyor 3 was retrieved and returned to Earth by the crew of ' Apollo 12 on November 121969
Conclusion:
The prospects for extraterrestrial life on Enceladus are very encouraging. "Enceladus is ... the fundamental chemical recipe for life A little bit of phosphorus and have everything you need to make the DNA -. Or perhaps a different DNA molecule." Robert Brown said: "[22]
On the basis of the existence of the critical ingredients of life, adaptability and a growing number of different extremophiles found thriving placesthat appear uninhabitable and hostile to life, being together with the amazing survival of microbes Surveyor 3, Enceladus seems to still hope to find extraterrestrial life. However, further exploration, analysis and research should be conducted to confirm the existence of this life, the ancient search for Planetology, as required, in the words of Carl Sagan (1934-1996), a legendary scientist , astronomer and writer, "Extraordinary claims outstandingEvidence. "[23]
During the Cassini flyby of Enceladus in 2006 and 2007 will perform the best chance to confirm the existence of extraterrestrial life, or approach in this direction is the 12th March 2008 Rendezvous. On this day the moon by Cassini of water clouds and ice particles will fly within 23 km (15 miles) from the surface of Enceladus' (when the Mission Control considered safe enough). But the probability of two-year extension of the Cassini missiondestined to end in 2008, and the missions are still needed, including landing probes (especially the south pole of Enceladus'), because in the words of Carolyn Porco, Cassini team leader at the Space Science Institute, "It is not clear that Cassini has the means to determine whether the ice crystals themselves contain microbes. It can be a device with much greater compositional rigor that we need, perhaps for a future mission that [because] we want to stayto do a better job of determining the composition of ICES from the quarries that contain the simplest organic compounds present in any other place. "[24]
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[1] Jeffrey Zweerink, Ph.D. Enceladus: liquid water, but not life.
[2] Richard Black. Saturn's moon 'best for life. "
[3] Enceladus (moon). Wikipedia.com.
[4] Enceladus (moon).Wikipedia.com.
[5] Enceladus (moon). Wikipedia.com.
[6] David Darling. cryovolcanism.
[7] Enceladus (moon). Wikipedia.com.
[8] Alan Boyle. Could support liquid water on Saturn moon life.
[9] Enceladus (moon). Wikipedia.com.
[10] Enceladus Erupting. Astrobiology Magazine.
[11] Bill Arnett. Enceladus. Saturn II
[12] The hydrothermal environments on the seafloor. and Dictionary.com.
[13] Peter N. Spotts. Life beyond Earth?Potential habitat of the solar system continue to appear.
[14] Michael Schirber. How life began: New research suggests a simple approach.
[15] David L. Chandler. Arctic Mars related instruments detect microbes.
[16] search for life on Mars will start in Siberia.
[17] For astrobiologists Hunt Small Game in Siberia. and Dictionary.com.
[18] Cold Environments of methane on the seabed.
[19] Life in extreme environments.
[20] hydrothermal environmentson the seabed.
[21] On Earth: extreme environments.
[22] Peter N. Spotts. Life beyond Earth? Potential habitat of the solar system continue to appear.
[23] Alan Boyle. Could support liquid water on Saturn moon life.
[24] David Leonardo. Saturn's moon inspires a gusher of questions.
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