reposted from DailyGalaxy
September 04, 2007
New Technologies & the Search for Extraterrestrial Life -A Galaxy Insight
Stanislaw Lem -author of the science-fiction classic, Solaris.
In his Summa Technologicae, famed science-fiction writer, Stanislaw Lem, goes on to say that "We think of ourselves as the Knights of the Holy Contact. This is another lie. We are only seeking Man. We have no need of other worlds...We are searching for an ideal image of our world: we go in quest of a planet, of a civilization superior to our own but developed on the basis of our primeval past."
It seems that NASA and read Lem and has taken his message to heart, with the recent publication of the National Research Council of its report, Limits of Organic Life in Planetary Systems. On the microbial level, most serious astronomers and scientists have little doubt that life will be found within the next decade within our Solar System in the Martian soil, or in the methane seas of Saturn's moon, Titan, or the turbid seas of Jupiter's smallest moon, Europa.
But, the tacit assumption that alien life would utilize the same biochemical architecture as life on Earth does means that scientists have artificially limited the scope of their thinking as to where extraterrestrial life might be found, the report says. The assumption that life requires water, for example, has limited thinking about likely habitats on Mars to those places where liquid water is thought to be present or have once flowed, such as the deep subsurface.
However, according to the committee, liquids such as ammonia or formamide could also work as biosolvents -- liquids that dissolve substances within an organism -- albeit through a different biochemistry. The recent evidence that liquid water-ammonia mixtures may exist in the interior of Saturn's moon Titan suggests that increased priority be given to a follow-on mission to probe Titan, a locale the committee considers the solar system's most likely home for weird life.
"It is critical to know what to look for in the search for life in the solar system," said report committee chair, John Baross, professor of oceanography at the University of Washington. "The search so far has focused on Earth-like life because that's all we know, but life that may have originated elsewhere could be unrecognizable compared with life here. Advances throughout the last decade in biology and biochemistry show that the basic requirements for life might not be as concrete as we thought."
Space missions will need adjustment to increase the breadth of their search for life. Planned Mars missions, for example, should include instruments that detect components of light elements -- especially carbon, hydrogen, oxygen, phosphorous, and sulfur -- as well as simple organic functional groups and organic carbon. Recent evidence indicates that another moon of Saturn, Enceladus, has active water geysers, raising the prospect that habitable environments may exist there and greatly increasing the priority of additional studies of this body.
Europa, Jupiter's smallest moon, might not only sustain, but foster life, according to the research of University of Arizona's Richard Greenberg, a professor of planetary sciences and member of the Imaging Team for NASA's Galileo Jupiter-orbiter spacecraft.
Europa, similar in size to Earth's moon, has been imaged by the Galileo Jupiter-orbiter spacecraft. Its surface, a frozen crust of water, was previously thought to be tens of kilometers thick, denying the oceans below any exposure. The combination of tidal processes, warm waters and periodic surface exposure may be enough not only to warrant life, but also to encourage evolution.
With Jupiter being the largest planet in the solar system, its tidal stresses on Europa create enough heat to keep the water on Europa in a liquid state. More than just water is needed to support life. Tides also play a role in providing for life. Ocean tides on Europa are much greater in size than Earth's with heights reaching 500 meters (more than 1,600 feet). Even the shape of the moon is stretched along the equator due to Jupiter's pull on the waters below the icy surface.
The mixing of substances needed to support life is also driven by tides. Stable environments are also necessary for life to flourish. Europa, whose orbit around Jupiter is in-synch with its rotation, is able to keep the same face towards the gas giant for thousands of years. The ocean is interacting with the surface, according to Greenberg, and "there is a possible biosphere that extends from way below the surface to just above the crust."
"The real key to life on Europa," Greenburg adds, "is the permeability of the ice crust. There is strong evidence that the ocean below the ice is connected to the surface through cracks and melting, at various times and places. As a result, the biosphere, if there is one, includes not just the liquid water ocean, but it extends through the ice up to the surface where there is access to oxidants, organic compounds, and light for photosynthesis. The physical setting provides a variety of potentially habitable and evolving niches. If there is life there, it would not necessarily be restricted to microorganisms."
Tides have created the two types of surface features seen on Europa: cracks/ridges and chaotic areas, Greenberg said.The ridges are thought to be built over thousands of years by water seeping up the edges of cracks and refreezing to form higher and higher edges until the cracks close to form a new ridge.
The chaotic areas are thought to be evidence of the melt-through necessary for exposure to the oceans.
The tidal heat, created by internal friction, could be enough to melt the ice, along with undersea volcanoes - a combination of factors would give organisms a stable but changing environment -- exactly the type that would encourage evolution.
The future NASA DepthX mission to Europa, scheduled for 2019, is a mushroom-shaped machine, an underwater hydrobot that 'thinks' for itself. DepthX is currently undergoing tests in one of the world's deepest flooded cave systems -the El Zacaton cave complex in Mexico- to simulate penetrating the Europea's ice-covered seas. The next version of the machine will be tested in Lake Vostok, a deep ice-covered lake in the Antarctic. The craft sent to Europa would use nuclear power to melt through the 10km of ice that cover the moon's ocean. The mission will be one of the most complex ever attempted by the American space agency NASA.
If all goes as planned the recently launched Phoenix Mission Spacecraft will set down on the arctic plains of the Red Planet on May 25, 2008, where it will then spend three months digging into the frozen Martian soil and ice, and analyzing the samples in miniature ovens and labs looking for traces of organic compounds in the baked and moistened samples. The 772-pound lander will stretch 18 feet across once its solar panels are deployed, and its weather mast will extend seven feet.
As our recent research in the Arctic and Antarctic regions on Earth have shown, If organic compounds are present on Mars, they're more likely to have been preserved in ice, which why NASA is aiming for the planet's high northern plains, where about six inches of soft red soil should cover the ice, and so the digger shouldn't have to probe too deeply.
Phoenix has the scientific capability "to change our thinking about the origins of life on other worlds," according to Peter H. Smith of the University of Arizona A Lunar and Planetary Laboratory and head of the Phoenix mission. "Even though the northern plains are thought to be too cold now for water to exist as a liquid, periodic variations in the Martian orbit allow a warmer climate to develop every 50,000 years. During these periods the ice can melt, dormant organisms could come back to life, (if there are indeed any), and evolution can proceed. Our mission will verify whether the northern plains are indeed a last viable habitat on Mars."
LPL Director Michael J. Drake said, "Phoenix has the potential to be the smoking gun for the evolution of life elsewhere in the universe. While it will not directly seek to detect life, it will look for complex organic molecules. If they are there, they are hinting strongly at present or past life...The discovery that we are not alone in the universe, that science fiction of Star Trek may in fact be science fact, will change the way humanity thinks about itself. The existence of even primitive life forms on Mars raises the probability of advanced life elsewhere, and emphasizes our commonality rather than our differences."
The search for extraterrestrial life and intelligence beyond the microbial level and beyond our Solar System continues at warp speed with the completion of SETI's Allen Array in the foothills of California's High Sierras (named after and funded by Microsoft co-founder, Paul Allen), the intense international search for viable exo-planets by the vast telescopic complex of the ESO and Las Campanas in Chile and the Anglo-Australian Search Team, and the upcoming European Space Agency's Darwin Mission.
Scientists' desire to detect what signals from beyond our Solar System that any life form might radiate into space—not just life that has evolved the technology to broadcast radio waves—lies at the root of the next generation of search technologies so that when they do detect Earth-like planets they know what to look for.
Malcolm Fridlund, a scientist with the European Space Agency (ESA) in the Netherlands, believes that if other planets follow a similar evolutionary pattern as Earth, it is much more likely that they will be inhabited by dinosaurs or bacteria rather than by something that can send emails.
Astrobiologists are now targeting more subtle signs that all life, not just intelligent life, might radiate into space. They call these telltale signatures 'biomarkers'. When ESA's Darwin mission begins sending back data in the next decade, biomarkers will help indicate whether neighboring planets are inhabited. If we only used radio waves as markers of life, this would exclude all forms of life that have not yet developed the means to emit radio waves. Life has been around for thousands of millions of years, but human beings have used radio waves for less than a century.
Fridlund is working on ESA's Darwin Project, which will launch in the 2015 time frame, aims to expand the search for life on planets orbiting suns outside our solar system to the detection of chemical signals that life might give off, such as oxygen, methane, and water vapor.
Darwin will use a flotilla of three space telescopes, each at least 3 meters in diameter, and a fourth spacecraft to server as communications, placed in an L2 orbit, 1.5 million kilometers from Earth. The telescopes will operate together to scan the nearby Universe, looking for signs of life on Earth-like planets. This is a daunting challenge and will require a number of technological innovations before the mission launches in the middle of the next decade.
"We have defined a scientific search for our origins and future, remembering that life has existed on this planet for at least 3.5 billion years, while intelligent life not very long indeed," he said.
The efforts of ESA are complemented by a similar program at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, known as the Terrestrial Planet Finder (TPF) with a launch anticipated between 2012-2015. . The effort seeks to search 50 to 150 nearby stars for Earth-like planets with signatures of life in their atmosphere.
The thrust behind Darwin and TPF is an idea first put forward by British scientist James Lovelock in the 1970s. Lovelock suggested that looking for similar distributions of atmospheric gas on other planets could be a way to search for life. Lovelock pointed out that, just by breathing, life affects the composition of the Earth's atmosphere. He suggested looking for similar effects as a way to search with telescopes for life on other planets. You can study the composition of an atmosphere by splitting a planet's light into a rainbow of colors. This 'spectrum' will contain dark lines made by various chemicals in the planet's atmosphere.
Darwin's strategy is to look for oxygen because oxygen is used by some life forms and produced as waste by others. Scientists believe that without life, all free oxygen in a planet's atmosphere would disappear within just four million years, because it reacts so easily with other chemicals. "The best estimates suggest that Darwin will be able to detect the build-up of oxygen caused within a few hundred million years of life's origin," says Fridlund.
To find these planets, the telescopes may take advantage of a technology known as interferometry, which combines the power of several small telescopes to produce a final sharp and detailed image.
Viewing in the infrared, these images will be of a spectrum of colors representing the different chemicals in the planet's atmosphere. Infrared Interferometer consist s of multiple small telescopes on a fixed structure or on separated spacecraft flying in precision formation would imitate a much larger, very efficient telescope. The interferometer would utilize a technique called nulling to reduce the starlight by a factor of one million, thus enabling the detection of the very faint infrared emission from the planets.
"What we are looking for is an atmosphere out of chemical equilibrium," said Fridlund. "Currently the Earth's atmosphere is out of such an equilibrium through its oxygen."
Although Darwin will not detect oxygen directly, it will 'see' ozone, a form of oxygen. It will also see carbon dioxide, water, and, in certain cases, methane. Fridlund says, "The general consensus is that if we find ozone, liquid water, and carbon dioxide simultaneously, it will be a very strong indicator of life's presence."
The work will not stop once Darwin completes its survey of the nearest several thousand star-planet systems. Once it finds a living planet, the race will be on to understand the nature of its life forms. That means searching for more specific biomarkers.
In future space missions, for example, scientists may use chlorophyll as a biomarker. This molecule allows plants and certain bacteria to use light as an energy source. "Finding the next generation of biomarkers is a very active field of research at the moment," says Fridlund.
Although it may sound like science fiction, Fridlund foresees a future in which space telescopes look for intelligent civilizations by searching for industrial pollution in a planet's atmosphere.
The SETI Allen Array which went online this May, is a 350 dish interferometer and will simultaneously conduct SETI research and radio astronomy.
The SETI institute is also partnering with NASA's Ames Research Center in Moffett Field, California, on the Kepler Mission, which will launch in 2007 and for the first time allow scientists to search for Earth-sized planets in orbit around distant stars and discover is planets like Earth are common or rare.
In our search for life and intelligence we have to keep in mind that the Milky Way Galaxy is two or three times the age of our Solar System, so there are going to be some societies out there that are millions of years, maybe more, beyond ours, which may have proceeded beyond biology—that have invented intelligent, self-relicating machines and it could be that what we first find is something that's artificially constructed if we have the ability to recognize it as such. It may very well be that our greatest discovery will be that the very nature of alien communication will prevent our being able to communicate with it.
Carl Sagan used to talk about the inhabitants of Borneo who are communicating with runners and drums. Meanwhile, there are radio shows going right through their bodies and their villages, of which they're totally unaware.
In his great science-fiction masterpiece, the Polish physician, Stanislaw Lem created the planet Solaris, which is discovered to contain an ocean that is a sentient living organism -a metaphor as well as a warning of alien incomprehensibility and human infancy.
Countless attempts by the space station Prometheus (a name associated with civilization and enlightenment in Greek mythology), which hovered a few hundred meters above its surface to establish contact proved fruitless. In the end the missions' scientists discovered only that "they were confronted with a monstrous entity endowed with reason, a protoplasmic ocean-brain enveloping the entire planet and idling its time away in extravagant theoretical cogitation about the nature of our universe. Our instruments had intercepted minute random fragments of a prodigious and everlasting monologue unfolding in the depths of this colossal brain, which was inevitably beyond our understanding."
Posted by Casey Kazan.
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