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UFO files reveal ‘Rendlesham incident’ papers missing

Intelligence papers on a reported UFO sighting known as the “Rendlesham incident” have gone missing, files from the National Archives reveal.

The missing files relate to a report of mysterious lights from US servicemen at RAF Woodbridge in Suffolk in 1980.

The disappearance came to light with the release of 8,000 previously classified documents on UFOs.

Officials found a “huge” gap where defence intelligence files relating to the case should be, the papers show.

 

Chissà magari col tempo li ritroveranno…….. .

P.S.

Per l’articolo completo in inglese: http://www.bbc.co.uk/news/uk-12613690

 

Fonte: http://www.bbc.co.uk

03/3/2011

 

Scoperta una stella simile al sole quando era «adolescente»

Ha un’attività di macchie solari paragonabile a quella del nostro astro quando aveva 500 milioni di anni

A mille anni luce dalla Terra c’ è una stella che si comporta come il nostro Sole quando aveva solo 500 milioni di anni, un’epoca in cui sulla Terra si stavano avviando i processi che avrebbero portato alla vita. La stella è caratterizzata da un’intensa variabilità, dovuta al rapido mutamento delle sue «macchie solari», simili a quelle che aveva il nostro astro quando era ancora «adolescente»: attività che probabilmente ebbero influenza sui primi meccanismi che avrebbero portato alla vita.

TEAM INTERNAZIONALE – La stella, ribattezzata CoRoT-Exo-2a, dal satellite che l’ha scoperta, è stata identificata da un team internazionale guidato da scienziati dell’Istituto Nazionale di Astrofisica ed è stata descritta in uno studio pubblicato su «Astronomy & Astrophysics». Per gli scienziati «se la presenza di un’intensa attività di origine magnetica sul Sole quando era così giovane, e la sua variabilità, hanno influenzato quegli eventi che hanno fatto nascere la vita sulla Terra, lo studio delle stelle di tipo solare condotto con il satellite CoRoT, e con altri telescopi da terra e dallo spazio, contribuiranno a chiarire l’influenza delle stelle sui pianeti durante quelle fasi cruciali della loro evoluzione». A scoprire CoRoT-Exo-2a è stato il satellite CoRoT, una missione spaziale condotta dall’Agenzia spaziale francese Cnes, con la partecipazione di Austria, Belgio, Brasile, Germania, Spagna e dell’Agenzia Spaziale Europea Esa, che comprende anche il contributo dell’Italia. La stella di tipo solare appena scoperta è accompagnata da un pianeta gigante di tipo «gioviano» che le orbita intorno. Lo studio delle variazioni intrinseche della stella è stato, invece, condotto da un altro gruppo internazionale, guidato da astronomi dell’Inaf-Osservatorio Astrofisico di Catania, con il contributo dell’Agenzia Spaziale Italiana Asi.

OSSERVAZIONE PROLUNGATA – «È la prima volta che una stella simile al Sole quando era giovane viene osservata ininterrottamente per 150 giorni, e con una precisione circa cento volte superiore a quella raggiungibile da Terra» spiega Antonino Francesco Lanza, dell’Inaf, primo autore dello studio pubblicato su «Astronomy & Astrophysics». Il risultato dell’osservazione è che la stella mostra variazioni di flusso di circa il 6 per cento, ovvero almeno 20 volte maggiori di quelle del Sole attuale, su un periodo di circa quattro giorni e mezzo. «Queste variazioni di flusso -spiega l’Inaf- sono prodotte da macchie, analoghe alle macchie solari, ma con un’area corrispondentemente maggiore, che si modificano continuamente mentre la stella ruota».

MINI-CICLO DI MACCHIE SOLARI – Le osservazioni di CoRoT hanno condotto così ad un risultato inatteso dagli scienziati, cioè l’esistenza di un mini-ciclo delle macchie la cui area totale varia con un periodo di soli 29 giorni. Nel caso del Sole il periodo di questi mini-cicli è però di circa 150 giorni. «Il più breve periodo nel caso di CoRoT-Exo-2a potrebbe essere dovuto -continua l’Inaf- alla rapida rotazione o alle perturbazioni dovute alla presenza del pianeta gigante a soli 4,2 milioni di chilometri dalla stella, ovvero ad appena il 3 per cento della distanza Terra-Sole».

NASA Spacecraft Detects Buried Glaciers on Mars

PASADENA, Calif. – NASA’s Mars Reconnaissance Orbiter has revealed vast Martian glaciers of water ice under protective blankets of rocky debris at much lower latitudes than any ice previously identified on the Red Planet.

Scientists analyzed data from the spacecraft’s ground-penetrating radar and report in the Nov. 21 issue of the journal Science that buried glaciers extend for dozens of miles from edges of mountains or cliffs. A layer of rocky debris blanketing the ice may have preserved the underground glaciers as remnants from an ice sheet that covered middle latitudes during a past ice age. This discovery is similar to massive ice glaciers that have been detected under rocky coverings in Antarctica.

“Altogether, these glaciers almost certainly represent the largest reservoir of water ice on Mars that is not in the polar caps,” said John W. Holt of the University of Texas at Austin, who is lead author of the report. “Just one of the features we examined is three times larger than the city of Los Angeles and up to one-half-mile thick. And there are many more. In addition to their scientific value, they could be a source of water to support future exploration of Mars.”

Scientists have been puzzled by what are known as aprons – gently sloping areas containing rocky deposits at the bases of taller geographical features – since NASA’s Viking orbiters first observed them on the Martian surface in the 1970s. One theory has been that the aprons are flows of rocky debris lubricated by a small amount of ice. Now, the shallow radar instrument on the Mars Reconnaissance Orbiter has provided scientists an answer to this Martian puzzle.

“These results are the smoking gun pointing to the presence of large amounts of water ice at these latitudes,” said Ali Safaeinili, a shallow-radar instruments team member with NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Radar echoes received by the spacecraft indicated radio waves pass through the aprons and reflect off a deeper surface below without significant loss in strength. That is expected if the apron areas are composed of thick ice under a relatively thin covering. The radar does not detect reflections from the interior of these deposits as would occur if they contained significant rock debris. The apparent velocity of radio waves passing through the apron is consistent with a composition of water ice.

Scientists developed the shallow radar instrument for the orbiter to examine these mid-latitude geographical features and layered deposits at the Martian poles. The Italian Space Agency provided the instrument.

“We developed the instrument so it could operate on this kind of terrain,” said Roberto Seu, leader of the instrument science team at the University of Rome La Sapienza in Italy. “It is now a priority to observe other examples of these aprons to determine whether they are also ice.”

Holt and 11 co-authors report the buried glaciers lie in the Hellas Basin region of Mars’ southern hemisphere. The radar also has detected similar-appearing aprons extending from cliffs in the northern hemisphere.

“There’s an even larger volume of water ice in the northern deposits,” said JPL geologist Jeffrey J. Plaut, who will be publishing results about these deposits in the American Geophysical Union’s Geophysical Research Letters. “The fact these features are in the same latitude bands, about 35 to 60 degrees in both hemispheres, points to a climate-driven mechanism for explaining how they got there.”

The rocky debris blanket topping the glaciers apparently has protected the ice from vaporizing, which would happen if it were exposed to the atmosphere at these latitudes.

“A key question is, how did the ice get there in the first place?” said James W. Head of Brown University, Providence, R.I. “The tilt of Mars’ spin axis sometimes gets much greater than it is now. Climate modeling tells us ice sheets could cover mid-latitude regions of Mars during those high-tilt periods. The buried glaciers make sense as preserved fragments from an ice age millions of years ago. On Earth, such buried glacial ice in Antarctica preserves the record of traces of ancient organisms and past climate history.”

JPL manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate in Washington. For more about the Mars Reconnaissance Orbiter, visit: http://www.nasa.gov/mro

Media contacts: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

2008-220

Are Aliens Among Us?

Are Aliens Among Us?
In pursuit of evidence that life arose on Earth more than once, scientists are searching for microbes that are radically different from all known organisms
By Paul Davies

COVER OF SCIENTIFIC AMERICAN, DEC. 07
If, as many scientists believe, life can readily emerge under the right environmental conditions, it is possible that life arose on Earth more than once. Researchers are now seeking evidence of a second genesis by searching for exotic microbes that are biochemically different from all known organisms. In this image, artist Adam Questell has imagined an alien cell that carries its genetic material in twin nuclei.
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Artist conception – SILICON LIFE-FORM
The most radically different aliens would be those based on silicon instead of carbon. Because silicon, like carbon, has a valence number of four (that is, the atom’s outermost orbital contains four electrons), silicon atoms can be arranged in rings and long chains that could form the backbones of biological molecules.
44F9077F-E7F2-99DF-35499556262F9CB3_2.jpg

Artist conception – SILICON LIFE-FORM
Scientists and science-fiction writers have long speculated about what a silicon-based life-form would look like. In an article for the Saturday Review, H. G. Wells wrote: One is startled towards fantastic imaginings by such a suggestion: visions of silicon-aluminium organisms…wandering through an atmosphere of gaseous sulphur, let us say, by the shores of a sea of liquid iron some thousand degrees or so above the temperature of a blast furnace.
44F9077F-E7F2-99DF-35499556262F9CB3_3.jpg

Artist conception – TINY ALIENS
The smallest bacteria have a diameter of about 200 nanometers. Autonomous organisms on our tree of life cannot be much smaller because they must contain protein-building cellular structures called ribosomes, which are each about 20 to 30 nanometers across. But if alien microbes could function without ribosomes, they could be comparable in size to the smallest viruses, which are only 20 nanometers wide.
44F9077F-E7F2-99DF-35499556262F9CB3_4.jpg

Artist conception – MIRROR LIFE
Large biological molecules can be configured into two mirror-image orientations: left-handed or right-handed. In all known life-forms, the amino acids are left-handed and DNA is a right-handed double helix. But if life started again from scratch, the amino acids could be right-handed and the DNA left-handed.
44F9077F-E7F2-99DF-35499556262F9CB3_5.jpg

Artist conception – AMINO ACIDS LIFE-FORM
All familiar organisms use, with rare exceptions, the same 20 amino acids to construct proteins, but chemists can synthesize many others. Alien microbes could incorporate unusual amino acids such as isovaline and pseudoleucine, which have been found in meteorites.

44F9077F-E7F2-99DF-35499556262F9CB3_6.jpg

Artist conception – ALIENS WITHIN US
Perhaps the most intriguing possibility of all is that alien life-forms inhabit our own bodies. While observing mammalian cells with an electron microscope in 1988, Olavi Kajander and his colleagues at the University of Kuopio in Finland observed ultrasmall particles inside many of the cells. With dimensions as small as 50 nanometers, these particles were about one-tenth the size of conventional small bacteria. Ten years later Kajander and his co-workers proposed that the particles were living organisms that thrive in urine and induce the formation of kidney stones by precipitating calcium and other minerals around themselves.
44F9077F-E7F2-99DF-35499556262F9CB3_7.jpg

Artist conception – ARSENIC LIFE-FORM
Researchers have hypothesized that in alien organisms arsenic could successfully fill the biochemical role that phosphorus plays for known life-forms. Arsenic is poisonous to us because it mimics phosphorus so well; similarly, phosphorus would be poisonous to an arsenic-based organism.
44F9077F-E7F2-99DF-35499556262F9CB3_8.jpg

Artist conception – VARIOUS LIFE-FORMS
It is possible that life arose on Earth several times, each time generating life-forms with different chemical characteristics.
44F9077F-E7F2-99DF-35499556262F9CB3_9.jpg

Are Aliens Among Us?

In pursuit of evidence that life arose on Earth more than once, scientists are searching for microbes that are radically different from all known organisms
By Paul Davies

If, as many scientists believe, life can readily emerge under the right environmental conditions, it is possible that life arose on Earth more than once. Researchers are now seeking evidence of a second genesis by searching for exotic microbes that are biochemically different from all known organisms.
Some of the best places to look for alternative life-forms are ecologically isolated niches such as ocean-bottom volcanic vents and the dry valleys of Antarctica.
Alien microbes may also lurk right under our noses. Scientists can hunt for these organisms by looking for the markers of alternative biochemistry.
The origin of life is one of the great unsolved problems of science. Nobody knows how, where or when life originated. About all that is known for certain is that microbial life had established itself on Earth by about three and a half billion years ago. In the absence of hard evidence of what came before, there is plenty of scope for disagreement.

Thirty years ago the prevailing view among biologists was that life resulted from a chemical fluke so improbable it would be unlikely to have happened twice in the observable universe. That conservative position was exemplified by Nobel Prize–winning French biologist Jacques Monod, who wrote in 1970: “Man at last knows that he is alone in the unfeeling immensity of the universe, out of which he emerged only by chance.” In recent years, however, the mood has shifted dramatically. In 1995 renowned Belgian biochemist Christian de Duve called life “a cosmic imperative” and declared “it is almost bound to arise” on any Earth-like planet. De Duve’s statement reinforced the belief among astrobiologists that the universe is teeming with life. Dubbed biological determinism by Robert Shapiro of New York University, this theory is sometimes expressed by saying that “life is written into the laws of nature.”

How can scientists determine which view is correct? The most direct way is to seek evidence for life on another planet, such as Mars. If life originated from scratch on two planets in a single solar system, it would decisively confirm the hypothesis of biological determinism. Unfortunately, it may be a long time before missions to the Red Planet are sophisticated enough to hunt for Martian life-forms and, if they indeed exist, to study such extraterrestrial biota in detail.

An easier test of biological determinism may be possible, however. No planet is more Earth-like than Earth itself, so if life does emerge readily under terrestrial conditions, then perhaps it formed many times on our home planet. To pursue this tantalizing possibility, scientists have begun searching deserts, lakes and caverns for evidence of “alien” life-forms—organisms that would differ fundamentally from all known living creatures because they arose independently. Most likely, such organisms would be microscopic, so researchers are devising tests to identify exotic microbes that could be living among us.

Scientists have yet to reach a consensus on a strict definition of life, but most would agree that two of its hallmarks are an ability to metabolize (to draw nutrients from the environment, convert those nutrients into energy and excrete waste products) and an ability to reproduce. The orthodox view of biogenesis holds that if life on Earth originated more than once, one form would have swiftly predominated and eliminated all the others. This extermination might have happened, for example, if one form quickly appropriated all the available resources or “ganged up” on a weaker form of life by swapping successful genes exclusively with its own kind. But this argument is weak. Bacteria and archaea, two very different types of microorganisms that descended from a common ancestor more than three billion years ago, have peacefully coexisted ever since, without one eliminating the other. Moreover, alternative forms of life might not have directly competed with known organisms, either because the aliens occupied extreme environments where familiar microbes could not survive or because the two forms of life required different resources.

The Argument for Aliens
Even if alternative life does not exist now, it might have flourished in the distant past before dying out for some reason. In that case, scientists might still be able to find markers of their extinct biology in the geologic record. If alternative life had a distinctively different metabolism, say, it might have altered rocks or created mineral deposits in a way that cannot be explained by the activities of known organisms. Biomarkers in the form of distinctive organic molecules that could not have been created by familiar life might even be hiding in ancient microfossils, such as those found in rocks dating from the Archean era (more than 2.5 billion years ago).

A more exciting but also more speculative possibility is that alternative life-forms have survived and are still present in the environment, constituting a kind of shadow biosphere, a term coined by Carol Cleland and Shelley Cop ley of the University of Colorado at Boulder. At first this idea might seem preposterous; if alien organisms thrived right under our noses (or even in our noses), would not scientists have discovered them already? It turns out that the answer is no. The vast majority of organisms are microbes, and it is almost impossible to tell what they are simply by looking at them through a microscope. Microbiologists must analyze the genetic sequences of an organism to determine its location on the tree of life—the phylogenetic grouping of all known creatures—and researchers have classified only a tiny fraction of all observed microbes.

To be sure, all the organisms that have so far been studied in detail almost certainly descended from a common origin. Known organisms share a similar biochemistry and use an almost identical genetic code, which is why biologists can sequence their genes and position them on a single tree. But the procedures that researchers use to analyze newly discovered organisms are deliberately customized to detect life as we know it. These techniques would fail to respond correctly to a different biochemistry. If shadow life is confined to the microbial realm, it is entirely possible that scientists have overlooked it.

Ecologically Isolated Aliens
Where might investigators look for alien organisms on Earth today? Some scientists have focused on searching for organisms occupying a niche that is ecologically isolated, lying beyond the reach of ordinary known life. One of the surprising discoveries in recent years is the ability of known life to endure extraordinarily harsh conditions. Microbes have been found inhabiting extreme environments ranging from scalding volcanic vents to the dry valleys of Antarctica. Other so-called extremophiles can survive in salt-saturated lakes, highly acidic mine tailings contaminated with metals, and the waste pools of nuclear reactors.

Nevertheless, even the hardiest microorganisms have their limits. Life as we know it depends crucially on the availability of liquid water. In the Atacama Desert in northern Chile is a region that is so dry that all traces of familiar life are absent. Furthermore, although certain microbes can thrive in temperatures above the normal boiling point of water, scientists have not yet found anything living above about 130 degrees Celsius (266 degrees Fahrenheit). It is conceivable, though, that an exotic alternative form of life could exist under more extreme conditions of dryness or temperature.

Thus, scientists might find evidence for alternative life by discovering signs of biological activity, such as the cycling of carbon between the ground and the atmosphere, in an ecologically isolated region. The obvious places to look for such disconnected ecosystems are in the deep subsurface of Earth’s crust, in the upper atmosphere, in Antarctica, in salt mines, and in sites contaminated by metals and other pollutants. Alternatively, researchers could vary parameters such as temperature and moisture in a laboratory experiment until all known forms of life are extinguished; if some biological activity persists, it could be a sign of shadow life at work. Scientists used this technique to discover the radiation-resistant bacterium Deinococcus radiodurans, which can withstand gamma-ray doses that are 1,000 times as great as what would be lethal for humans. It turns out that D. radiodurans and all the other so-called radiophiles that researchers have identified are genetically linked to known life, so they are not candidate aliens, but that finding does not rule out the possibility of discovering alternative life-forms in this way.

Investigators have already pinpointed a handful of ecosystems that appear to be almost completely isolated from the rest of the biosphere. Located far underground, these microbial communities are cut off from light, oxygen and the organic products of other organisms. They are sustained by the ability of some microbes to use carbon dioxide and hydrogen released by chemical reactions or radioactivity to metabolize, grow and replicate. Although all the organisms found to date in these ecosystems are closely related to surface-dwelling microbes, the biological exploration of Earth’s deep subsurface is still in its infancy, and many surprises may lie in store. The Integrated Ocean Drilling Program has been sampling rocks from the seabed to a depth approaching one kilometer, in part to explore their microbial content. Boreholes on land have revealed signs of biological activity from even deeper locations. So far, however, the research community has not conducted a systematic, large-scale program to probe the deep subsurface of Earth’s crust for life.

Ecologically Integrated Aliens
One might suppose it would be easier to find alternative life-forms if they were not isolated but integrated into the known biosphere existing all around us. But if shadow life is restricted to alien microbes that are intermingled with familiar kinds, the exotic creatures would be very hard to spot on casual inspection. Microbial morphology is limited—most microorganisms are just little spheres or rods. Aliens might stand out biochemically, though. One way to search for them is to make a guess as to what alternative chemistry might be involved and then look for its distinctive signature.

A simple example involves chirality. Large biological molecules possess a definite handedness: although the atoms in a molecule can be configured into two mirror-image orientations—left-handed or right-handed—molecules must possess compatible chirality to assemble into more complex structures. In known life-forms, the amino acids—the building blocks of proteins—are left-handed, whereas the sugars are right-handed and DNA is a right-handed double helix. The laws of chemistry, however, are blind to left and right, so if life started again from scratch, there would be a 50–50 chance that its building blocks would be molecules of the opposite handedness. Shadow life could in principle be biochemically almost identical to known life but made of mirror-image molecules. Such mirror life would not compete directly with known life, nor could the two forms swap genes, because the relevant molecules would not be interchangeable.

Fortunately, researchers could identify mirror life using a very simple procedure. They could prepare a nutrient broth consisting entirely of the mirror images of the molecules usually included in a standard culture medium; a mirror organism might be able to consume the concoction with gusto, whereas a known life-form would find it unpalatable. Richard Hoover and Elena Pikuta of the NASA Marshall Space Flight Center recently performed a pilot experiment of this kind, putting a variety of newly discovered extremophiles into a mirror broth and then looking for biological activity. They found one microbe that grew in the broth, an organism dubbed Anaerovirgula multivorans that had been isolated from the sediments of an alkaline lake in California. Disappointingly, this organism did not turn out to be an example of mirror life; rather it was a bacterium with the surprising ability to chemically alter the amino acids and sugars of the wrong handedness so as to make them digestible. The study, however, looked at just a small fraction of the microbial realm.

Another possibility is that shadow life might share the same general biochemistry with familiar life but employ a different suite of amino acids or nucleotides (the building blocks of DNA). All known organisms use the same set of nucleotides—designated A, C, G and T for their distinguishing bases (adenine, cytosine, guanine and thymine)—to store information and, with rare exceptions, the same 20 amino acids to construct proteins, the workhorses of cells. The genetic code is based on triplets of nucleotides, with different triplets spelling out the names of different amino acids. The sequence of triplets in a gene dictates the sequence of amino acids that must be strung together to build a particular protein. But chemists can synthesize many other amino acids that are not present in known organisms. The Murchison meteorite, a cometary remnant that fell in Australia in 1969, contained many common amino acids but also some unusual ones, such as isovaline and pseudoleucine. (Scientists are not sure how the amino acids formed in the meteorite, but most researchers believe that the chemicals were not produced by biological activity.) Some of these unfamiliar amino acids might make suitable building blocks for alternative forms of life. To hunt for such aliens, investigators would need to identify an amino acid that is not used by any known organisms nor generated as a by-product of an organism’s metabolism or decay, and to look for its presence in the environment, either among living microbes or in the organic detritus that might be generated by a shadow biosphere.

To help focus the search, scientists can glean clues from the burgeoning field of synthetic, or artificial, life. Biochemists are currently attempting to engineer completely novel organisms by inserting additional amino acids into proteins. A pioneer of this research, Steve Benner of the Foundation for Applied Molecular Evolution in Gainesville, Fla., has pointed out that a class of molecules known as alpha-methyl amino acids look promising for artificial life because they can fold properly. These molecules, however, have not been found in any natural organism studied to date. As investigators identify new microbes, it would be a relatively simple matter to use standard tools for analyzing the composition of proteins, such as mass spectrometry, to learn which amino acids the organisms contain. Any glaring oddities in the inventory would signal that the microbe could be a candidate for shadow life.

If such a strategy were successful, researchers would face the difficulty of determining whether they were dealing with a genuine alternative form of life descended from a separate origin or with merely a new domain of known life, such as archaea, which were not identified until the late 1970s. In other words, how can scientists be sure that what seems like a new tree of life is not in fact an undiscovered branch of the known tree that split away a very long time ago and has so far escaped our attention? In all likelihood, the earliest life-forms were radically different from those that followed. For example, the sophisticated triplet DNA code for specifying particular amino acids shows evidence of being optimized in its efficiency by evolutionary selection. This observation suggests the existence of a more rudimentary precursor, such as a doublet code employing only 10, rather than 20, amino acids. It is conceivable that some primitive organisms are still using the old precursor code today. Such microbes would not be truly alien but more like living fossils. Nevertheless, their discovery would still be of immense scientific interest. Another possible holdover from an earlier biological epoch would be microbes that use RNA in place of DNA.

The chance of confusing a separate tree of life with an undiscovered branch of our own tree is diminished if one considers more radical alternatives to known bio chemistry. Astrobiologists have speculated about forms of life in which some other solvent (such as ethane or methane) replaces water, although it is hard to identify environments on Earth that would support any of the suggested substances. (Ethane and methane are liquid only in very cold places such as the surface of Titan, Saturn’s largest moon.) Another popular conjecture concerns the basic chemical elements that make up the vital parts of known organisms: carbon, hydrogen, oxygen, nitrogen and phosphorus. Would life be possible if a different element were substituted for one of these five?

Phosphorus is problematic for life in some ways. It is relatively rare and would not have existed in abundance in readily accessible, soluble form under the conditions that prevailed during the early history of Earth. Felisa Wolfe-Simon, formerly at Arizona State University and now at Harvard University, has hypothesized that arsenic can successfully fill the role of phosphorus for living organisms and would have offered distinct chemical advantages in ancient environments. For example, in addition to doing all the things that phosphorus can do in the way of structural bonding and energy storage, arsenic could provide a source of energy to drive metabolism. (Arsenic is a poison for regular life precisely because it mimics phosphorus so well. Similarly, phosphorus would be poisonous to an arsenic-based organism.) Could it be that arseno-life still lingers in phosphorus-poor and arsenic-rich pockets, such as ocean vents and hot springs?

Another important variable is size. All known organisms manufacture proteins from amino acids using large molecular machines called ribosomes, which link the amino acids together. The need to accommodate ribosomes requires that all autonomous organisms on our tree of life must be at least a few hundred nanometers (billionths of a meter) across. Viruses are much smaller—as tiny as 20 nanometers wide—but these agents are not autonomous organisms because they cannot reproduce without the help of the cells they infect. Because of this dependence, viruses cannot be considered an alternative form of life, nor is there any evidence that they stem from an independent origin. But over the years several scientists have claimed that the biosphere is teeming with cells that are too small to accommodate ribosomes. In 1990 Robert Folk of the University of Texas at Austin drew attention to tiny spheroidal and ovoid objects in sedimentary rocks found in hot springs in Viterbo, Italy. Folk proposed that the objects were fossilized “nannobacteria” (a spelling he preferred), the calcified remains of organisms as small as 30 nanometers across. More recently, Philippa Uwins of the University of Queensland has discovered similar structures in rock samples from a deep-ocean borehole off the coast of Western Australia. If these structures indeed arise from biological processes—and many scientists hotly dispute this contention—they may be evidence of alternative life-forms that do not use ribosomes to assemble their proteins and that thus evade the lower size limit that applies to known life.

Perhaps the most intriguing possibility of all is that alien life-forms inhabit our own bodies. While observing mammalian cells with an electron microscope in 1988, Olavi Kajander and his colleagues at the University of Kuopio in Finland observed ultrasmall particles inside many of the cells. With dimensions as small as 50 nanometers, these particles were about one-tenth the size of conventional small bacteria. Ten years later Kajander and his co-workers proposed that the particles were living organisms that thrive in urine and induce the formation of kidney stones by precipitating calcium and other minerals around themselves. Although such claims remain controversial, it is conceivable that at least some of these Lilliputian forms are alien organisms employing a radically alternative biochemistry.

What Is Life, Anyway?
If a biochemically weird microorganism should be discovered, its status as evidence for a second genesis, as opposed to a new branch on our own tree of life, will depend on how fundamentally it differs from known life. In the absence of an understanding of how life began, however, there are no hard-and-fast criteria for this distinction. For instance, some astrobiologists have speculated about the possibility of life arising from silicon compounds instead of carbon compounds. Because carbon is so central to our biochemistry, it is hard to imagine that silicon- and carbon-based organisms could have emerged from a common origin. On the other hand, an organism that employed the same suite of nucleotides and amino acids as known life-forms but merely used a different genetic code for specifying amino acids would not provide strong evidence for an independent origin, because the differences could probably be explained by evolutionary drift.

A converse problem also exists: dissimilar organisms subjected to similar environmental challenges will often gradually converge in their properties, which will become optimized for thriving under existing conditions. If this evolutionary convergence were strong enough, it could mask the evidence for independent biogenesis events. For example, the choice of amino acids may have been optimized by evolution. Alien life that began using a different set of amino acids might then have evolved over time to adopt the same set that familiar life-forms use.

The difficulty of determining whether a creature is alien is exacerbated by the fact that there are two competing theories of biogenesis. The first is that life begins with an abrupt and distinctive transformation, akin to a phase transition in physics, perhaps triggered when a system reaches a certain threshold of chemical complexity. The system need not be a single cell. Biologists have proposed that primitive life emerged from a community of cells that traded material and information and that cellular autonomy and species individuation came later. The alternative view is that there is a smooth, extended continuum from chemistry to biology, with no clear line of demarcation that can be identified as the genesis of life.

If life, so famously problematic to define, is said to be a system having a property—such as the ability to store and process certain kinds of information—that marks a well-defined transition from the nonliving to the living realm, it would be meaningful to talk about one or more origin-of-life events. If, however, life is weakly defined as something like organized complexity, the roots of life may meld seamlessly into the realm of general complex chemistry. It would then be a formidable task to demonstrate independent origins for different forms of life unless the two types of organisms were so widely separated that they could not have come into contact (for instance, if they were located on planets in different star systems).

It is clear that we have sampled only a tiny fraction of Earth’s microbial population. Each discovery has brought surprises and forced us to expand our notion of what is biologically possible. As more terrestrial environments are explored, it seems very likely that new and ever more exotic forms of life will be discovered. If this search were to uncover evidence for a second genesis, it would strongly support the theory that life is a cosmic phenomenon and lend credence to the belief that we are not alone in the universe.

ABOUT THE AUTHOR(S)
Paul Davies is a theoretical physicist, cosmologist and astrobiologist. He is currently director of Beyond, a research center at Arizona State University devoted to exploring the big questions of science. Davies is the author or co-author of 27 books; his latest work is Cosmic Jackpot: Why Our Universe Is Just Right for Life (Houghton Mifflin, 2007).

www.sciam.com

INCONTRI RAVVICINATI

INCONTRI RAVVICINATI
1991, un pilota Alitalia:
“C’è un Ufo su Londra”
Il ministero della Difesa britannico rende pubblici i file sugli avvistamenti misteriosi avvenuti fra il 1986 e il 1992: 19 i casi. C’è anche la testimonianza di un capitano dell’Alitalia, nell’aprile del 1991

Londra, 20 ottobre 2008. – Il ministero della Difesa britannico ha desecretato i file sugli avvistamenti di Ufo e tra i casi più bizzarri c’è quello di un comandante dell’Alitalia che segnalò la presenza di un oggetto volante mentre si apprestava ad atterrare all’aeroporto londinese di Heathrow.

«Attenzione, attenzione!» disse al copilota il capitano Achille Zaghetti nella cabina di comando di un volo partito da Milano il 21 aprile del 1991. La torre di controllo, subito allertata da Zaghetti, confermò l’avvistamento. La sera dello stesso giorno una emittente televisiva locale mandò in onda la testimonianza di un 14enne che diceva di aver visto un missile volare rasoterra, impennarsi e sparire tra le nuvole.
Le analisi delle tracce radar non confermarono che si trattasse di un missile da crociera e l’oggetto fu classificato come Ufo.

I file dell’Archivio Nazionale riguardano 19 episodi accaduti tra il 1986 e il 1992. In una lettera datata marzo 1990, una donna raccontava di essere una aliena precipitata sulla terra durante la Seconda guerra mondiale insieme a due uomini provenienti dal pianeta Spectra a bordo di una nave spaziale recuperata dall’esercito britannico.

XFiles in Sicilia

Tra la costa di Caronia e le isole Eolie, scienziati e generali incaricati dallo Stato studiano fenomeni inspiegabili che dal 2004 tormentano gli abitanti. Vi mostriamo alcune foto che fanno nascere molti dubbi

La copertina del MagazineNon chiamateli dischi volanti perché ingegneri, ammiragli e generali, architetti, geologi e fisici da quattro anni a caccia del mistero dell’acqua e del fuoco potrebbero decidere di continuare a tacere. E lasciare il top secret su una blindatissima banca dati con 350 eventi fra avvistamenti, rilievi di campi magnetici, bolle marine dal diametro di un chilometro, distese di melanzane colore arcobaleno e così via fino ad alcune inedite, ancora inspiegabili, foto mozzafiato con oggetti circolari sospesi sull’isola di Vulcano. Tutti strani fenomeni concentrati fra le Eolie e la costa di Caronia, quella segnata dall’angoscia di una piccola comunità di abitanti a partire dal 2004 strabiliati e allarmati davanti a incendi improvvisi, a Tv ed elettrodomestici che si accendevano da soli o prendevano fuoco, come le lampade e i ma- N terassi, mentre i cellulari si ricaricavano senza essere collegati a niente e sui display apparivano strambi caratteri.

Non chiamateli dischi volanti nemmeno con i carabinieri che hanno dovuto verbalizzare un collega testimone di una accecante “luce” in cielo, o l’altro al quale prese fuoco una scarpa. Vietata la tipica terminologia da ufologi anche con protezione civile, esercito, aeronautica e marina, università e vulcanologi, tutti timorosi di passare per matti e dubbiosi su cause e ipotesi, ma convinti di un solo dato comune: la concentrazione di fenomeni elettromagnetici in un’area ristretta.

Appunto, quella di Canneto, un pugno di case sul mare, cinquanta residenti, una striscia stretta fra la costa e la linea ferroviaria Palermo-Messina, un rettangolo sottoposto ai raggi X di servizi segreti e sentinelle elettroniche. Tutti impegnati a scoprire perché, soprattutto nell’inverno e nella primavera 2004, proprio in questo buco nero, si smagnetizzavano le pen drive, impazzivano le bussole, si aprivano e chiudevano senza impulsi i cancelli automatici e gli allarmi delle automobili, con sensori e rivelatori di fumo attivati anche senza scosse e fiamme, fino all’implosione dei vetri di una utilitaria e al foro su un parabrezza, «colpito dalla punta di un trapano invisibile», come dichiarò il proprietario e portavoce degli abitanti di Canneto, Nino Pezzino.

Anomalie elettromagnetiche ufficialmente spazzate via da una archiviazione della magistratura che nel 2007 ha impresso al caso il bollo di “un fenomeno di natura dolosa e umana”. Come dire che si sarebbe trattato di un piromane. Però, ancora ignoto. Spiegazione inaccettabile per le “vittime”di Canneto, con intere famiglie evacuate per mesi dalle loro case. Spiegazione insufficiente per gli abitanti fra i quali Antonino Spinnato, un agricoltore con la passione delle foto, tanti scatti finiti alla banca dati, certo di aver visto fino a metà agosto strani oggetti volanti fotografati come gli è capitato di fare con quello che seguiva un elicottero della Protezione civile costretto a un atterraggio per avaria alle pale.

Spiegazione precaria anche per chi scansa i termini da ufologo, ma continua a studiare i fenomeni da un osservatorio istituito con decreto della presidenza del Consiglio nel 2005, il cosiddetto “Gruppo interistituzionale” (vedi box a pag. 60). Una task force che ha come quartier generale un ufficio della Regione siciliana in pieno centro a Palermo, ottavo piano di un edificio moderno, le vetrate sulla cupola del Teatro Massimo e una banca dati che ha già interessato pure i servizi segreti perché un primo riservato fascicolo consegnato a Protezione civile e Palazzo Chigi avanza anche l’ipotesi di “test militari segreti o esperimenti alieni”.

Il tutto con mille dubbi legati a documenti mai pubblicati. È il caso di una foto scattata da un mezzo militare nelle acque di Vulcano il 2 agosto del 2004. Una clamorosa immagine che lascia interdetti perché sul profilo dell’isola sembrano sospesi due oggetti che fanno subito pensare ai dischi volanti. Ingrandito il fotogramma e studiato ogni dettaglio dell’istantanea con sofisticate attrezzature, i tecnici dei diversi enti presenti nel Gruppo hanno solo potuto escludere l’ipotesi del fotomontaggio. «Proprio perché sembrano due dischi volanti procediamo con i piedi di piombo in assenza di conclusioni scientificamente definite », commenta a denti stretti il coordinatore del Gruppo, Francesco Venerando, quando scopre che la foto è comunque arrivata al Corriere della Sera Magazine superando dopo quattro anni la barriera del top secret.

Nei documenti ufficiali si continua a parlare di “due Ovni”, termine che sta per “oggetti volanti non identificati”. Ma si aggiunge che quello stesso 2 agosto del 2004 un Ovni di forma analoga fu osservato nel cielo di Trapani, mentre il 29 luglio, appena quattro giorni prima, un altro dello stesso tipo era stato avvistato su Rometta Marea, a pochi chilometri da Caronia. Informazioni queste ultime arrivate dal Centro ufologico nazionale. Dati incamerati da Venerando con cautela: «Il Gruppo nasce per fare luce sui fenomeni, non per catalogare l’avvistamento di “Ovni”. Ma abbiamo dovuto applicarci anche a questo. E per ogni segnalazione abbiamo ovviamente cercato di controllare le registrazioni radar…», ammette Venerando, anche lui sorpreso perché gli “oggetti” non lasciano tracce. Bisogna però fare i conti con la magistratura che parla di ignoti “piromani” o con l’analogo parere di Enzo Boschi, il presidente dell’Istituto nazionale di Geofisica e vulcanologia: «Penso che dietro ci sia un bel dolo…».

Non tutti comunque conoscono i contenuti di una banca dati con foto celate da vistosi “Riservato”. Come è accaduto per gran parte degli oltre trecento eventi. Tutti elencati su paginate elettroniche a colori. Pagine in viola per malesseri e morie di animali, a decine. In azzurro, gli avvistamenti di “Ovni”, più di 100. In giallo, gli incendi, 40. In verde, fenomeni di origine elettronica e elettromagnetica, 100. Non a caso una relazione tecnica fresca di stampa elenca «numerose testimonianze di avvistamenti diurni e notturni di Ovni, di improvvisi bagliori e scie, di forti luminescenze nello specchio di mare compreso tra le Eolie, in particolare le Isole Alicudi, Filicudi e la costa di Caronia, che iniziano nel 2004 e si ripetono abbastanza spesso, fino a oggi…».

Cauto, Venerando si limita a parlare di “una origine artificiale dei fenomeni”, di “emissioni elettromagnetiche impulsive” capaci di generare “una grande potenza concentrata in frazioni di tempo estremamente ridotte”. E quale sorgente potrebbe mai assicurare sto po’ po’ di roba? Sulla “fonte” o sul “soggetto” allarga le braccia: «Potrebbe anche trattarsi di applicazioni sperimentali di tecnologie industriali, non escludendo quelle finalizzate a recenti sistemi d’arma a energia elettromagnetica… ». Un modo forse per lasciar trapelare la possibilità di esperimenti da parte di una potenza militare. Ignota comunque la posizione della “fonte”. Forse, il mare. Forse, sott’acqua. Mistero profondo. Per questo si decise di installare una rete di telecamere e termocamere a infrarossi tutt’intorno a Canneto e diversi sensori sulla costa e sulle isole Eolie nel tentativo di dare la caccia non solo all’eventuale piromane mai trovato, ma a quello che nei rapporti riservati viene definito “l’impulso sorgente proveniente dal mare”.

Telecamere e sensori sono stati collegati per tre anni in tempo reale con i computer del “Gruppo” da una sala regia collocata sull’attico più vicino al mare, l’appartamento di una delle “vittime” di Cannetto, Antonio Caico, un signore stanco che però ha mollato e venduto la proprietà. Per continuare l’attività sarebbe bastato spostare le attrezzature costate 150 mila euro in un prefabbricato sul mare, come chiese Venerando. E invece stop, tutti “accecati”. Con le apparecchiature adesso ammassate in un magazzino del Comune di Caronia. Come rivela Venerando, irritato dall’interruzione del monitoraggio: «Non possiamo più controllare l’area, come facevamo a qualsiasi ora, via Intranet». Il tutto a costo zero, assicura, perché ogni componente del Gruppo opera senza rimborsi, senza budget, come dipendenti degli enti rappresentati. «Il sistema consentiva di rilevare molteplici dati attorno ai fenomeni », si rammarica Venerando. «Volevamo installare altri sensori anche alle spalle di Caronia, sulle vallate interne, a Lipari e Salina, per creare una rete capace di individuare il “punto sorgente”». Sarebbe stata così interrotta un’esperienza unica in Italia, «in un’area geografica oggettivamente sensibile», stando a Venerando che parla di «un’attività d’interpretazione scientifica coniugata con gli studi e le recenti esperienze della ricerca cosiddetta “di confine” ». E dire che sulle telecamere abbandonate in magazzino, sulla necessità di ripristinare il monitoraggio c’è pure un’interpellanza bipartisan in Senato presentata l’anno scorso da 17 parlamentari.

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Nella foto (che il Magazine del Corriere della Sera pubblica in esclusiva) scattata il 2 agosto 2004 da un mezzo militare in navigazione di fronte all’isola di Vulcano, si possono notare due oggetti volanti che fanno pensare agli Ufo. Lo scatto è stato giudicato dagli esperti non ritoccato in alcun modo.
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All’attacco di un elicottero. Nel marzo 2006 un abitante di Canneto vede un elicottero in difficoltà, scatta una foto e scopre che alle spalle del mezzo compare un altro oggetto. L’elicottero è della Protezione civile in missione sull’area proprio per investigare sugli Ufo. Ma il volo è interrotto da una improvvisa anomalia
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All’attacco di un elicottero. Nel marzo 2006 un abitante di Canneto vede un elicottero in difficoltà, scatta una foto e scopre che alle spalle del mezzo compare un altro oggetto. L’elicottero è della Protezione civile in missione sull’area proprio per investigare sugli Ufo. Ma il volo è interrotto da una improvvisa anomalia
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Se il raccolto di melanzane diventa improvvisamente di un altro colore, qui c’è chi pensa che la colpa potrebbe essere degli alieni. Soprattutto se la verdura in questione da nera diventa verde, colore che piace tanto agli extraterrestri. Siamo a Marina di Caronia dove, nel marzo 2006, un’intera piantagione di melanzane cresce inspiegabilmente di questo colore (in foto) facendo perdere ai coltivatori 3.000 pezzi che nessuno vuole e molti soldi. Inutili le analisi di laboratorio che non hanno saputo piegare il fenomeno.
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Ampelodesmos bruciato. Tra gli incendi del 2004, il più inquietante ha bruciato tutte le piante della specie “Ampelodesmos mauritanicus”, mentre ha lasciato integri tutti gli altri esemplari. E’ esclusa l’ipotesi di un intervento umano. Le radici di centinaia di piante erano infatti carbonizzate fino in profondità nel suolo.
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Coincidenze cinesi. Nel 2006 il pilota Vincenzo Garofalo fotografa a Punta Raisi una sorta di astronave. La stessa navicella (stessa forma, dentatura e torrette laterali) è disegnata sulla copertina di un libro del 1980, Ufos China, che ritrae un avvistamento del 1942 a Xiao Tian
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Le cozze spiaggiate. Altra coincidenza, nel 2004, fu lo spiaggiamento di milioni di esemplari di Velella a Marina di Caronia. La Velella è chiamata “barchetta di San Pietro”, somiglia a una cozza senza coperchio, con una vela. A volte grandi quantità raggiungono le coste dopo forti venti o per improvvise variazioni termiche. Condizioni meteo però mai segnalate in zona in quei giorni.

Felice Cavallaro
08 settembre 2008(ultima modifica: 09 settembre 2008)