Wednesday, February 22, 2006

"SETI Is The Only Research Program Looking For Life Beyond The Solar System"

Allen Array My Art
Scientists look for extraterrestrial life

     Scientists are ramping up the search for extraterrestrial life with a powerful array of new telescopes and a refined sense of where to look within the vast expanses of our universe.

At the annual conference of the American Association for the Advancement of Science last weekend, a panel of experts discussed the key components of life and what it might mean to find them within our own solar system -- or beyond.

Even in the absence of a breakthrough discovery, Nathalie Cabrol of the Mountain View, Calif.-based SETI Institute said such efforts could pay big dividends for thinking about life on an ever-changing Earth.

"It is the way we are going to understand where we are coming from and how we are going to survive as a species," she said. With a growing list of microbes capable of living in Earth's harshest conditions and hints of Earth-like features on Mars and Saturn's moon Titan, "our notion of habitability in our own solar system and the rest of the universe is going to change over time," Cabrol said.

Although NASA's Spirit and Opportunity rovers continue trundling across Mars and gathering evidence that the Red Planet once harbored water, SETI (Search for Extraterrestrial Intelligence) is the only research program looking for life beyond the solar system.

Water, energy and nutrients are considered key elements for a habitable planet. But SETI researchers acknowledged that whether habitable means inhabited is a different question entirely, especially since Earth is the only known example.

Jill Tartar, who heads the Center for SETI Research at the nonprofit institute, put the enormity of the challenge into perspective: 100 billion galaxies are believed to exist, each with 100 billion stars. So far, scientists have detected the presence of about 180 planets in orbit around 147 stars beyond our solar system, though most of them are inhospitable giant balls of gas, akin to Jupiter.

So where to begin?

Margaret Turnbull of the Carnegie Institution of Washington has helped to whittle down a preliminary list of nearly 120,000 stars so her colleagues can focus on the ones best suited for a terrestrial planet.

Among her considerations, Turnbull said a star's solar system should include a "habitable zone" that allows liquid water. Also, a star more than 1.5 times the size of our Sun likely wouldn't live long enough to allow advanced life, and stars younger than 3 billion years likely wouldn't allow enough time for advanced life forms to establish themselves.

After scrutinizing all the candidates, Turnbull ended up with a list of 17,129 stars.

"So we've got our work cut out for us," she said.

One star on her shortlist, named 18 Sco, is a virtual solar twin to the Sun. Another, called 51 Peg, already is known to have a giant gaseous planet akin to Jupiter in its orbit.

To aid in the exhaustive search, SETI is setting up the Allen Telescope Array, a joint project with the Radio Astronomy Laboratory at the University of California at Berkeley.

The northern California-based cluster of 350 radio antennas, slated for completion in June, 2008, will allow astronomers to look for new planets or listen for radio transmissions sent from intelligent civilizations in other solar systems.

Tartar said previous technologies allowed researchers to scan about 1,000 stars over a decade. With the Allen Telescope Array, funded largely by Seattle billionaire Paul Allen, SETI scientists believe they will be able to search at least one million stars in the coming decade.

Other space missions under consideration by NASA could aid the search, but Tartar complained that the space agency's budget proposal for astrobiology in fiscal year 2007 has been cut by 50 percent compared with its 2005 budget, leading to worries that such missions could be delayed indefinitely.

Searches for far smaller signs of life are ongoing as well. Pascale Ehrenfreund of the Leiden Institute of Chemistry in the Netherlands said scientists have identified about 140 kinds of molecules in space -- two-thirds of which include carbon, the common denominator of life on Earth. Carbon chemistry throughout the universe seems to follow the same pathways, she said, leading many scientists to suggest a carbon-focused search for identifying other life forms.

Carol Cleland, a professor of philosophy at the University of Colorado at Boulder, believes that approach may be too narrow, however.

"We should be looking for life as we don't know it," she said, by trying to identify systems that appear similar to those on Earth, but which contain provocative anomalies that might be indicative of wildly different forms of life.

And if scientists are eventually successful? SETI's Margaret Pace said finding even primitive signs of life close to home -- on Mars, for example -- may raise difficult policy questions, an issue she said should be thoroughly discussed beforehand.

"It's sort of like getting a message on your answering machine," she said. We may be able to decide whether to respond to a call from a distant planet, but identifying something alive closer to home will not afford us the same luxury.

Tartar predicted that the search could yield headlines within a few decades, "but we won't know if we've found microbes or mathematicians."

Unlike the movie "Contact," in which Jodie Foster portrays a character loosely based on her, Tartar said her institute will be prepared. "We have champagne on ice," she said, "and they forgot that."

More . . .

See Also: Shostak Responds to Recent "SETI Politics" Article


1 comment :

    by John Umana

    I thought I'd share my current thinking on the deep questions of astrobiology and the emergence of life:

    (1) There is no other life in this sun system. Mars contains no life and never did, notwithstanding that 70% of scientists polled believe that there is or was life on Mars at one time. This conventional wisdom is mistaken. Saturn's moon Titan contains no life and never did. No other planet or object, no comet, no asteroid in this sun system contains any form of life. Europa does not contain liquid seas under the ice. When NASA gets there after 2010 or so, we’ll see that there are no fishes swimming around. Only Earth in this sun system contains seas of liquid water at this time, though Mars once did have shallow seas as the rovers Spirit and Opportunity and the orbiters have found. Where did/does the water come from on Earth and (billions of years ago) on Mars? Volcanoes produce large amounts of water steam, and they are largely responsible for Earth's oceans. Other released gases from volcanoes included carbon dioxide (CO2), sulfur dioxide (SO2), hydrochloric acid (HCl), hydrogen fluoride (HF), hydrogen sulfide (H2S), carbon monoxide (CO), molecular hydrogen gas (H2), NH3, methane (CH4), silicon tetrafluoride (SiF4), and minor amounts of nitrogen (N2) and argon (Ar). But no oxygen. … And no life. Plenty of hydrogen, however, is a great start. The name is derived from the Greek ‘hydro genes,’ meaning water forming. Though most of our water came from volcanoes, carbonaceous chondrites, among the most primitive objects in our sun system, contain water locked up in phyllosilicate minerals with the water content making up about 10% by weight of the meteorites. Comets and meteorites also gave us some water.

    (2) In my respectful opinion, the Universe including our galaxy is teeming with life. All life throughout the vast cosmos is nucleotide, DNA-based. (OK, you're right, I don't have the proof today but hoping that mankind will come up with the proof during this new millenium.)

    (3) In my respectful opinion, the Universe including our galaxy is teeming with intelligent life. (The reason SETI is not picking them up is they are unlikely to be communicating by radio or any type of electromagnetic communication -- far too slow for the distances involved.)

    (4) Extraterrestrial astronauts did not “seed” mankind or life on Earth. The theory of panspermia is way off the mark. No need to keep worrying about whether comets could have carried spores of life here; that's not what happened and the distances are too vast for a living spore to hitch a ride on a comet in any event. There is no life beyond Earth for a long, long ways.

    (5) Darwin's/Wallace's theory of the evolutionary theory of common ancestry is proved conclusively by the convergence of the entire scientific and fossil record, including paleontology, molecular biology, genetics, mitochondrial DNA, Y-chromosome DNA, comparative anatomy and physiology, biogeography, geology and archaeology. I do not believe there was a single common ancestor RNA strand, rather; there was differentiation right from the first period of emergence into what would become the plant and animal kingdoms. No common ancestor with life on other habitable worlds. Life emerged separately and independently on Earth.

    (6) The Darwinian theory of "natural selection" as the mechanism for origin of the species is unsubstantiated, overly simplistic, and runs contrary to what is observed in modern microbiology. It is bad science as theory of emergence or origin of species, though natural selection is a true force of nature and accounts for such phenomena as pesticide resistance of insects (e.g., the mosquitos that survive an application of a given pesticide eventually develop an immunity to it over time) or the resistance of bacteria to antibiotics. Natural selection (NS) is not the causative mechanism for the evolution of a single species on Earth or anywhere else. The neo-Darwinists are way, way off the mark as to the specific mechanism of evolution as microbiology is beginning to demonstrate. NS was an interesting guess back in the 1800’s. Less interesting today with microbiology. Whatever the right answer is as to emergence and origin of species, it isn't NS.

    (7) Life emerged on Earth independently of other habitable worlds -- just shy of 4.0 billion years ago at the tail end of the Heavy Bombardment.

    (8) Where/how first life emerged on Earth? Just shy of 4 billion years ago. Pick an area where the critical amino acids are found. Prep needed. Areas under the shallow seas at that time and sheltered puddles where seas met rocky shore, protected from UV rays. Black smokers come much later; emergence of life there was much more difficult. Sheltered areas protected from lethal and destabilizing UV rays including areas under the seas. Still massive comet strikes nearly every day or few days, equivalent to thermonuclear blasts, sending massive seismic shock waves throughout mantle and core. Temperature out a balmy 200-300 degrees; more inhospitable as approach areas adjacent to live volcanos. Pre-biotic Earth temperature range roughly -288 F to +260 F. At night, temperatures dropped sharply as on the moon without protective atmosphere. No free oxygen to speak of on Earth. No ozone screen 10-15 miles up in atmosphere to protect emergence of first life from lethal UV. Earth highly radioactive as remnant of solar nebula, creating enormous challenge to emergence of first RNA strand; no membrane at first; highly unstable molecule. Thin atmosphere of H2O, CO2, SO2, N2. Stark sunlight. Pristine earth. No blue sky. Whispy clouds occasionally high up. More like sunlight falling across face of moon or Mars (but no pink sky like Mars). Because of gamma radiation, UV and wild temperature swings, only rapidly reproducing self-replicating strands possible, containing backup DNA files for self-repair when damaged by radiation or UV -- until Earth cools off radioactively within the next few billion years (as of 4 bya). That's the reason why there was no evolution beyond single cells until 583 million years ago or so with emergence of Ediacara biota and some 40 million years later with the Cambrian explosion of life. [John Umana All rights reserved.]

    Have a good day!


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