Man has started thinking and it became leads to so many INNOVATIONS and many Ideas,Researches,Experiments.......
And now they are searching for LIFE in other planets in our solar system and behalf of that......
And now they are searching for LIFE in other planets in our solar system and behalf of that......
For as long as humans have looked to the night sky to divine meaning and a place in the universe, we have let our minds wander to thoughts of distant worlds populated by beings unlike ourselves. The ancient Greeks were the first Western thinkers to consider formally the possibility of an infinite universe housing an infinite number of civilizations. Much later, in the 16th century, the Copernican model of a heliocentric solar system opened the door to all sorts of extraterrestrial musings (once the Earth was no longer at the center of creation and was merely one body in a vast cloud of celestial objects, who was to say God hadn't set other life-sustaining worlds into motion?) While that line of thinking never sat well with the church, speculation about alien life kept pace with scientific inquiry up through the Enlightenment and on into the twentieth century.
But it wasn't until the close of the 1950s that anyone proposed a credible way to look for these distant, hypothetical neighbors. The space age had dawned, and science was anxious to know what lay in wait beyond the confines of our thin, insulating atmosphere. The Russians had, in 1957 and 1958, launched the first three Sputnik satellites into Earth orbit; the United States was poised to launch in 1960 the successful Pioneer 5 interplanetary probe out toward Venus. We were readying machines to travel farther than most of us could imagine, but in the context of the vast reaches of outer space, we would come no closer to unknown planetary systems than if we'd never left Earth at all.
Our only strategy was to hope intelligent life had taken root elsewhere and evolved well beyond our technological capabilities—to the point at which they could call us across the empty plains of space. Our challenge was to figure out which phone might be ringing and how exactly to pick it up. And so it was in mid-September of 1959 that two young physicists at Cornell University authored a two-page article in Nature magazine entitled "Searching for Interstellar Communications." With that, the modern search for extraterrestrial life was born, and ""life on Earth would never again be the same."""
When water was discovered on Mars, people got very excited. Where there is water, there may be life. Scientists are planning new missions to study the planet up close. NASA’s next Mars rover is scheduled to arrive in 2010. In the decade following, a Mars Sample Return mission might be launched, which would use robotic systems to collect samples of Martian rocks, soils, and atmosphere, and return them to Earth. We could then analyze the sample to see if it contains any traces of life, whether extinct or still active. Such a discovery would be of tremendous scientific significance. What could be more fascinating than discovering life that had evolved entirely independently of life here on Earth? Many people would also find it heartening to learn that we are not entirely alone in this vast cold cosmos.
But it wasn't until the close of the 1950s that anyone proposed a credible way to look for these distant, hypothetical neighbors. The space age had dawned, and science was anxious to know what lay in wait beyond the confines of our thin, insulating atmosphere. The Russians had, in 1957 and 1958, launched the first three Sputnik satellites into Earth orbit; the United States was poised to launch in 1960 the successful Pioneer 5 interplanetary probe out toward Venus. We were readying machines to travel farther than most of us could imagine, but in the context of the vast reaches of outer space, we would come no closer to unknown planetary systems than if we'd never left Earth at all.
Our only strategy was to hope intelligent life had taken root elsewhere and evolved well beyond our technological capabilities—to the point at which they could call us across the empty plains of space. Our challenge was to figure out which phone might be ringing and how exactly to pick it up. And so it was in mid-September of 1959 that two young physicists at Cornell University authored a two-page article in Nature magazine entitled "Searching for Interstellar Communications." With that, the modern search for extraterrestrial life was born, and ""life on Earth would never again be the same."""
When water was discovered on Mars, people got very excited. Where there is water, there may be life. Scientists are planning new missions to study the planet up close. NASA’s next Mars rover is scheduled to arrive in 2010. In the decade following, a Mars Sample Return mission might be launched, which would use robotic systems to collect samples of Martian rocks, soils, and atmosphere, and return them to Earth. We could then analyze the sample to see if it contains any traces of life, whether extinct or still active. Such a discovery would be of tremendous scientific significance. What could be more fascinating than discovering life that had evolved entirely independently of life here on Earth? Many people would also find it heartening to learn that we are not entirely alone in this vast cold cosmos.
The MOON that would be a PLANET.....TITAN
Titan, Saturn’s largest natural satellite, scarcely deserves to be a called a mere moon. It has an atmosphere thicker than Earth’s and a surface that is almost as varied.
If we had not known the images were coming back from Titan, we might have guessed they were new pictures of Mars or Earth. Some people in the control room saw the California coast, some saw the French Riviera, and one person even said that Saturn’s biggest moon looked like his backyard in Tucson. For three weeks, the Huygens probe had coasted, dormant, after detaching from the Cassini spacecraft and being sent on its way to Titan. Those of us watching anxiously felt a deep personal connection with the probe. Not only had we worked on the mission for a large part of our careers, but we had developed its systems and instrumentation by putting our minds in its place, to think through how it would function on an alien and largely unknown world. We imagined Titan might be like the comparably large moons of the outer solar system, such as Jupiter’s cratered Callisto or grooved Ganymede.
And so on the morning of January 14, 2005, at the European Space Operations Center in
Darmstadt, Germany, the pictures caused jubilation and puzzlement in equal measure. None
of us expected the landscape to look so Earth like.As Huygens parachuted down, its aerial
pictures showed branching river channels cut by rain-fed streams. It landed on the damp, pebble covered site of a recent flash flood. What was alien about Titan was its eerie familiarity.
Now, five years on, we have had time to digest the probe’s findings and put them in the bigger picture that Cassini, having flown past Titan more than 60 times in its looping orbit around Saturn, has gradually pieced together. In size (bigger than Mercury), dynamism (more active than Mars) and atmosphere (thicker than Earth’s), Titan is a planet by any other name. A wide variety of geologic processes shape its surface. Methane plays the role that water does on Earth. It evaporates from lakes, forms clouds, precipitates out, carves valleys and flows back into lakes. If only the atmosphere had some oxygen and the temperature were not –180 degrees Celsius, you would feel at home on Titan.
Seas of Sand, Seas of Methane
Before Cassini, perspective on Titan was very one-dimensional. When the Voyager spacecraft flew by in 1980 and 1981, it saw only a hazesh rouded,
orangish billiard ball, and the best that observatories in the mid-1990s could manage was a crude infrared map showing vaguely dark and bright areas. Scientists talked in terms of Titan’s surface or its atmosphere, as if a single measured quantity or descriptive phrase could capture an entire world. These generalizations have withered under the barrage of new data. We now have to refer to the low-latitude sand seas, or the atmosphere
above the north pole in summer, or a cloudy day in the southern lake district. Titan’s low latitudes are a mix of rugged, bright hills, most notably the vast area named Xanadu, and dark sand seas, once thought to be liquid seas. (Astronomers are always tempted to call dark areas “seas,” the lunar mares being the most obvious example.) Sand dunes 100 meters high, like the largest dunes found on Earth, stretch for tens to hundreds of kilometers. The dark sand on Titan is not made of silicate minerals such as quartz, as on Earth, but of hydrocarbons, looking rather like heaps of
coffee grounds. Around the poles, we find liquid hydrocarbons: small lakes in steep pits a few tens of kilometers across; shallow play a such as Ontario
Lacus, slightly larger than its namesake of Lake Ontario; and seas such as Kraken Mare, as big as the Caspian. The surface level of these lakes
appears to have changed with time. Wedged in between the desert like tropics and the wet polar regions are the strangely inscrutable mid latitudes,
with heavily eroded landscapes and evidence of flowing liquid.
If we had not known the images were coming back from Titan, we might have guessed they were new pictures of Mars or Earth. Some people in the control room saw the California coast, some saw the French Riviera, and one person even said that Saturn’s biggest moon looked like his backyard in Tucson. For three weeks, the Huygens probe had coasted, dormant, after detaching from the Cassini spacecraft and being sent on its way to Titan. Those of us watching anxiously felt a deep personal connection with the probe. Not only had we worked on the mission for a large part of our careers, but we had developed its systems and instrumentation by putting our minds in its place, to think through how it would function on an alien and largely unknown world. We imagined Titan might be like the comparably large moons of the outer solar system, such as Jupiter’s cratered Callisto or grooved Ganymede.
And so on the morning of January 14, 2005, at the European Space Operations Center in
Darmstadt, Germany, the pictures caused jubilation and puzzlement in equal measure. None
of us expected the landscape to look so Earth like.As Huygens parachuted down, its aerial
pictures showed branching river channels cut by rain-fed streams. It landed on the damp, pebble covered site of a recent flash flood. What was alien about Titan was its eerie familiarity.
Now, five years on, we have had time to digest the probe’s findings and put them in the bigger picture that Cassini, having flown past Titan more than 60 times in its looping orbit around Saturn, has gradually pieced together. In size (bigger than Mercury), dynamism (more active than Mars) and atmosphere (thicker than Earth’s), Titan is a planet by any other name. A wide variety of geologic processes shape its surface. Methane plays the role that water does on Earth. It evaporates from lakes, forms clouds, precipitates out, carves valleys and flows back into lakes. If only the atmosphere had some oxygen and the temperature were not –180 degrees Celsius, you would feel at home on Titan.
Seas of Sand, Seas of Methane
Before Cassini, perspective on Titan was very one-dimensional. When the Voyager spacecraft flew by in 1980 and 1981, it saw only a hazesh rouded,
orangish billiard ball, and the best that observatories in the mid-1990s could manage was a crude infrared map showing vaguely dark and bright areas. Scientists talked in terms of Titan’s surface or its atmosphere, as if a single measured quantity or descriptive phrase could capture an entire world. These generalizations have withered under the barrage of new data. We now have to refer to the low-latitude sand seas, or the atmosphere
above the north pole in summer, or a cloudy day in the southern lake district. Titan’s low latitudes are a mix of rugged, bright hills, most notably the vast area named Xanadu, and dark sand seas, once thought to be liquid seas. (Astronomers are always tempted to call dark areas “seas,” the lunar mares being the most obvious example.) Sand dunes 100 meters high, like the largest dunes found on Earth, stretch for tens to hundreds of kilometers. The dark sand on Titan is not made of silicate minerals such as quartz, as on Earth, but of hydrocarbons, looking rather like heaps of
coffee grounds. Around the poles, we find liquid hydrocarbons: small lakes in steep pits a few tens of kilometers across; shallow play a such as Ontario
Lacus, slightly larger than its namesake of Lake Ontario; and seas such as Kraken Mare, as big as the Caspian. The surface level of these lakes
appears to have changed with time. Wedged in between the desert like tropics and the wet polar regions are the strangely inscrutable mid latitudes,
with heavily eroded landscapes and evidence of flowing liquid.
Titan’s Ice Ages
In addition to weather patterns occurring on a seasonal cycle and atmospheric replenishment occurring over geologic time, both Titan and
Earth undergo climate change over intermediate periods of tens of thousands to millions of years. As first realized by 19th-century Scottish.
scientist James Croll and later refined by Serbian geophysicist Milutin Milankovic in the early 20th century, gravitational forces exerted by the other planets slowly shift Earth’s tilt and orbit, altering the intensity of solar heating and giving rise to the cycle of ice ages. On Titan, the so thern summer is shorter but more intense than it is in the north, because Saturn (and therefore Titan) has an elliptical orbit around the sun.It is about 10 percent closer to the sun during southern midsummer. These asymmetric seasons may pump volatile compounds such as methane and ethane from thesouth to the north, which now has far more lakes and seas. Over time, however, the relative alignment of Titan’s pole and Saturn’s elliptical orbit shifts. In 30,000 years the northern summer will be the more intense one. Lakes will dry up in the north, and new ones will form in the south. It is yet another way that Titan is more like a terrestrial planet than an icy moon.
Cassini’s findings of an exotic yet familiar landscape are prompting scientists to look at Earth in a new way. For example, Titan’s fields of linear sand dunes resemble those in the Namib or Saharan deserts, where the dunes line up along the average of two dominant wind directions. Yet atmospheric simulations for Titan have trouble reproducing the dune orientations.
The discrepancy may be a sign that scientists do not fully understand the formation of such dunes or that Titan’s winds are controlled by effects not yet included in the simulations. Moreover, observations of Titan’s lakes so far show them to be dead flat, with no waves on the surface, even though the lower gravity and thicker air should, if anything, increase the wave strength. What does this stillness mean for our understanding of wind-wave generation? Titan’s rotation rate may vary slightly with the seasons as the atmosphere and surface spin each other up and down like giant flywheels—an effect that is also seen, albeit much weaker, on Earth. Thus, as is often the case in planetary exploration,Cassini’s findings are prompting deeper questions. The rich range of scientific problems posed by Titan and the complex surface-atmosphere interactions will ultimately require a series of missions—just like NASA’s Mars program—including landers, rovers, even balloons. Meanwhile Cassini continues to fly by Titan every few weeks. Last August marked the northern spring equinox on Titan, and as the sun progressively moves north, the atmospheric circulation
and cloud patterns will change before our eyes. As the northern polar regions, which have been in cold, stagnant darkness, warm up, the one thing we can expect is the unexpected
A Deluge of Methane-TITAN
Methane undergoes a short term cycle (black) much like the water cycle on Earth. Over geologic time there is an episodic one-way flow (white) of methane from interior reservoirs to the upper atmosphere, where solar radiation converts it to ethane and heavier hydrocarbon—forming the haze. The particulates settle onto the surface as what Carl Sagan called “manna from heaven.”
Titan’s atmosphere, like Earth’s, has a troposphere (a lower, dynamic layer where weather takes place) and a stratosphere (a stable layer heated by solar ultraviolet radiation). These and other layers are defined by the change of temperature with height (right). Titan’s atmosphere is more than 200 degrees colder and, because of the satellite’s weaker gravity,vertically stretched. Multiple layers of haze, consisting of hydrocarbon particulates akin to smog, play the same role as Earth’s ozone layer.
Titan’s atmosphere, like Earth’s, has a troposphere (a lower, dynamic layer where weather takes place) and a stratosphere (a stable layer heated by solar ultraviolet radiation). These and other layers are defined by the change of temperature with height (right). Titan’s atmosphere is more than 200 degrees colder and, because of the satellite’s weaker gravity,vertically stretched. Multiple layers of haze, consisting of hydrocarbon particulates akin to smog, play the same role as Earth’s ozone layer.
Locations in the SOLAR SYSTEM to search for LIFE
Many bodies in the Solar System have been suggested as being capable of containing conventional organic life. The most commonly suggested ones are listed below; of these, five of the ten are moons, where large bodies of underground liquid (oceans) are considered possible. Life there may have evolved in a way similar to biological communities surrounding deep sea vents.
Numerous other bodies have been suggested as potential hosts for microbial life. Fred Hoyle has proposed that life might exist on comets, as some Earth microbes managed to survive on a lunar probe for many years (later considered doubtful as sterile procedures may not have been fully followed). However, it is considered highly unlikely that complex multicellular organisms of the conventional chemistry of terrestrial life (i.e. animals and plants) could exist under these living conditions.
- Venus — Recently, scientists have speculated on the existence of microbes in the stable cloud layers 50 km above the surface, evidenced by hospitable climates and chemical disequilibrium.
- Mars — Life on Mars has been long speculated. Liquid water is widely thought to have existed on Mars in the past, and there may still be liquid water beneath the surface. Methane was found in the atmosphere of Mars and work is underway to discern its biological or abiotic origin. By July 2008, laboratory tests aboard NASA's Phoenix Mars Lander had identified water in a soil sample. The lander's robotic arm delivered the sample to an instrument which identifies vapors produced by the heating of samples. Recent photographs from the Mars Global Surveyor show evidence of recent (i.e. within 10 years) flows of a liquid on the Red Planet's frigid surface.
- Ceres (dwarf planet–asteroid) — There has been some speculation that life could have evolved early on Ceres and have survived up to the present.
- Jupiter — Carl Sagan and others in the 1960s and 70s computed conditions for hypothetical amino acid-based macroscopic life in the atmosphere of Jupiter, based on observed conditions of this atmosphere. However, the conditions do not appear to permit the type of encapsulation believed necessary for molecular biochemistry, so life is thought to be unlikely.
- Europa (Moon of Jupiter) — Europa contains liquid water beneath its thick ice layer. It is possible that vents on the bottom of the ocean warm the ice, so liquid exists beneath the ice layer, perhaps capable of supporting microbes and simple plants, just like in Earth's hydrothermal vents. It is also possible that Europa could support aerobic macrofauna using oxygen created by cosmic rays impacting its surface ice.
- Ganymede (Largest moon of Jupiter) — Possible underground ocean (see Europa).
- Callisto (Moon of Jupiter) — Possible underground ocean (see Europa).
- Titan (Largest moon of Saturn) — The only known moon with a significant atmosphere. Data from the Cassini–Huygens mission refuted the hypothesis of a global hydrocarbon ocean, but later demonstrated the existence of liquid hydrocarbon lakes in the polar regions—the first liquid lakes discovered outside of Earth. Analysis of data from the mission has uncovered aspects of atmospheric chemistry near the surface which are consistent with —but do not prove— the hypothesis that organisms there are consuming hydrogen, acetylene and ethane, and producing methane.
- Enceladus (Moon of Saturn) — Geothermal activity, water vapor. Possible under-ice oceans heated by tidal effects. When Cassini did a fly-by through one of Enceladus's geysers spewing ice and gas in 2005, the probe detected carbon, hydrogen, nitrogen and oxygen -- all key elements for supporting living organisms. What's more, the temperature and density of the plumes could indicate a warmer, watery source beneath the surface. Still, no life has been confirmed. Yet.
- Exoplanets - Some estimates show that the Milky Way alone harbors around 400 billion stars and countless exo planets, and that’s just within our own galaxy. So there could potentially be billions of habitable cosmic bodies out there.
- Orion Nebula - A stellar nursery in the Milky Way has recently been investigated as a potential gold mine for finding life.
Numerous other bodies have been suggested as potential hosts for microbial life. Fred Hoyle has proposed that life might exist on comets, as some Earth microbes managed to survive on a lunar probe for many years (later considered doubtful as sterile procedures may not have been fully followed). However, it is considered highly unlikely that complex multicellular organisms of the conventional chemistry of terrestrial life (i.e. animals and plants) could exist under these living conditions.
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The Cassini spacecraft, using its radar system, has discovered very strong evidence for hydrocarbon lakes on Titan. Dark patches, which resemble terrestrial lakes, seem to be sprinkled all over the high latitudes surrounding Titan's north pole. Image CREDIT: NASA/JPL
One of the major goals of NASA's Cassini mission was to find lakes or seas on Saturn's moon Titan. Now scientist say they've found lakes. These are not bodies of water like those on Earth, but rather dark lakes of methane and possibly ethane. They are likely the source of the hydrocarbon smog in the moon's atmosphere that has long made it impossible to even see the surface.
Several dark patches, some with channels running out of them, were spotted near Titan's north pole during a July 22 Cassini flyby, NASA said in a statement yesterday.
"This is a big deal," said Steve Wall, deputy radar team leader at NASA's Jet Propulsion Laboratory. "We've now seen a place other than Earth where lakes are present." This was Cassini's first look at the region. Its radar, which penetrates the smog, was used to find several dozen lakes ranging from less than a mile wide to one that is about 62 miles long."What we see is darker than anything we've ever seen elsewhere on Titan. It was almost as though someone laid a bull's-eye around the whole north pole of Titan, and Cassini sees these regions of lakes just like those we see on Earth," said Larry Soderblom, Cassini interdisciplinary scientist at the U.S. Geological Survey, Flagstaff, Ariz. On radar, dark areas indicate smoother terrain.
These apparent lakes are so dark that the scientists assume they must be liquid. Any water on Titan would be constantly frozen, however, so the assumption is these lakes are made of hydrocarbons, which can stay liquid at much colder temperatures.The shapes of outflow channels strongly suggest liquid carved them, the researchers say."We've always believed Titan's methane had to be maintained by liquid lakes or extensive underground 'methanofers,' the methane equivalent of aquifers," said Jonathan Lunine, a Cassini scientist at the University of Arizona. "We can't see methanofers but we can now say we've seen lakes."Lakes should change shape slightly with the seasons, and winds ought to roughen their surfaces, so future passes by Cassini will look for these effects.Other Cassini observations have revealed apparent river channels elsewhere on the moon, as well as shorelines that might represent lakes or seas. Scientists say the moon likely experiences methane rains.But most observations, until now, have not shown conclusively that the methane exists in large quantities in liquid form now. Cassini has been observing Saturn and its moons and rings since it arrived there two years ago. It is a cooperative project between NASA, the European Space Agency and the Italian Space Agency.
One of the major goals of NASA's Cassini mission was to find lakes or seas on Saturn's moon Titan. Now scientist say they've found lakes. These are not bodies of water like those on Earth, but rather dark lakes of methane and possibly ethane. They are likely the source of the hydrocarbon smog in the moon's atmosphere that has long made it impossible to even see the surface.
Several dark patches, some with channels running out of them, were spotted near Titan's north pole during a July 22 Cassini flyby, NASA said in a statement yesterday.
"This is a big deal," said Steve Wall, deputy radar team leader at NASA's Jet Propulsion Laboratory. "We've now seen a place other than Earth where lakes are present." This was Cassini's first look at the region. Its radar, which penetrates the smog, was used to find several dozen lakes ranging from less than a mile wide to one that is about 62 miles long."What we see is darker than anything we've ever seen elsewhere on Titan. It was almost as though someone laid a bull's-eye around the whole north pole of Titan, and Cassini sees these regions of lakes just like those we see on Earth," said Larry Soderblom, Cassini interdisciplinary scientist at the U.S. Geological Survey, Flagstaff, Ariz. On radar, dark areas indicate smoother terrain.
These apparent lakes are so dark that the scientists assume they must be liquid. Any water on Titan would be constantly frozen, however, so the assumption is these lakes are made of hydrocarbons, which can stay liquid at much colder temperatures.The shapes of outflow channels strongly suggest liquid carved them, the researchers say."We've always believed Titan's methane had to be maintained by liquid lakes or extensive underground 'methanofers,' the methane equivalent of aquifers," said Jonathan Lunine, a Cassini scientist at the University of Arizona. "We can't see methanofers but we can now say we've seen lakes."Lakes should change shape slightly with the seasons, and winds ought to roughen their surfaces, so future passes by Cassini will look for these effects.Other Cassini observations have revealed apparent river channels elsewhere on the moon, as well as shorelines that might represent lakes or seas. Scientists say the moon likely experiences methane rains.But most observations, until now, have not shown conclusively that the methane exists in large quantities in liquid form now. Cassini has been observing Saturn and its moons and rings since it arrived there two years ago. It is a cooperative project between NASA, the European Space Agency and the Italian Space Agency.