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Tuesday, March 25, 2008

Signs of Hidden Ocean Underneath Titan's Crust

Slippage in Titan's rotation suggests water between its surface and core—and a higher likelihood of ancient life on Saturn's biggest moon

titan ocean


TITAN'S HIDDEN OCEAN: A strange shift in the position of mountains and lakes on the surface of Saturn's moon Titan can best be explained, researchers say, by positing a layer of liquid water (blue) some 100 kilometers below the surface.

Astronomers' mental image of Titan, the solar system's second-largest moon, used to be that of a vast swimming pool. But maybe they should have imagined a water bed instead.

Last year, researchers reported that radar mapping of Titan by the Cassini spacecraft had found a peculiar shift in landmarks on the moon's surface of up to 19 miles (30 kilometers) between October 2004 and May 2007.

Now investigators say the best explanation is a moon-wide underground ocean that disconnects Titan's icy crust from its rocky interior.

"We think the structure is about 100 kilometers of ice sitting atop a global layer of water … maybe hundreds of kilometers thick," says Cassini scientist Ralph Lorenz of Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

If confirmed, Titan would be the fourth moon in the solar system thought to contain such an internal water ocean, joining Jupiter's satellites Ganymede, Callisto and Europa. Researchers believe that heat from radioactivity in a moon's core or gravitational squeezing may melt a layer of frozen water.

On Titan, Ganymede and Callisto, the liquid would become sandwiched between two different forms of ice, one that floats on water and one that sinks. Astronomers believe that of the four bodies, Europa has a larger and hotter core that directly borders its ocean, which lies beneath a thin layer of ice.

A hidden water layer would add to Titan's impressive resume: Larger in diameter than both Earth's moon and the planet Mercury, Titan is the only satellite in the solar system with a true atmosphere—a dense, rotating fog of nitrogen supporting hydrocarbon clouds made of methane and ethane.

For decades researchers suspected that its frosty surface temperature of around –290 degrees Fahrenheit (–180 degrees Celsius) would cause hydrocarbons to pool on its surface in a vast ocean. But during Cassini's first flyby in October 2004, its radar instruments detected no surface-spanning ocean, only methane lakes near the moon's north pole.

The shift in Titan's geologic features is strange because the moon is locked in a synchronous orbit around Saturn, meaning it always presents the same face to the planet. "It's a little bit improbable that Titan would be rotating asynchronously," Lorenz says.

Writing in Science, he and his colleagues instead connect the geologic displacement to models in which Titan's atmosphere pushes against mountains on the surface.

The exact thickness of the crust is an important component of the group's model of Titan but is not known precisely. Based on the dimensions of the Menrva impact crater, they estimate a thickness of about 60 miles (100 kilometers).

That would make the crust thinner than those of Ganymede or Callisto, where the oceans are thought to lie below as much as 125 miles (200 kilometers) of rock and ice. For Titan's presumed ocean to remain liquid at such a distance from the hot core, the researchers argue that it must contain ammonia.

There may also be other explanations for the observed shifting. In an editorial accompanying the report, planetary scientists Christophe Sotin of the Jet Propulsion Laboratory at the California Institute of Technology (Caltech), Gabriel Tobie of the University of Nantes in France, observe that a periodic wobble in Titan's rotation or, less likely, a recent asteroid impact could also explain the finding.

The ocean interpretation is still the most plausible one, according to David Stevenson, professor of planetary science at Caltech. "This is a perfectly natural thing to do in a water–ice dominated world, provided there is enough heat," he says.

What is less clear, he adds, is the ocean's depth. The movement of the crust likely depends on additional, poorly understood factors, such as seasonal weather patterns and gravitational attraction between the crust and the core, he says.

Luckily, the group's model is testable. It predicts a quickening of Titan's rotation rate in the coming year or two followed by a slowdown—something that can be measured on succeeding Cassini flybys.

As always, the possibility of water leads to talk of potential life. Researchers have speculated that Titan may have long ago harbored life or its building blocks, catalyzed by sunlight reacting with atmospheric carbon and hydrogen.

Experts have considered Europa a better candidate, however, because of the presumed contact between ocean and core, which would provide a steady supply of heat energy.

Lorenz and his colleagues note that Titan's ocean might be stirred instead by cryovolcanism or warmer (but still cold) water welling up from below. The addition of water, Lorenz says, makes Titan "astrobiologically very appealing."

Stevenson, for one, says he still sees Europa as a better bet for life. He agrees that Titan is an attractive natural laboratory for the kind of chemistry that would lead to life, but when it comes to energy sources, sizzling rock "is much better than ice."

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Sky Whales & Pagoda Forests -Is Evolution Possible on Planets Beyond Our Solar System?

Skywhale_2What form would evolution take on life-bearing planets similar in size to earth? With the intense effort of the world's astronomers in their search for earth-like planets beyond our solar system, scientists are putting extra thought into the concept of alien evolution and have come up with some interesting results.

It's an attempt to come up with "creatures, that, although fanciful, are plausible," says Michael Meyer, an astrobiologist and the lead scientist for NASA's Mars Exploration Program.

Using the expertise of a number of renowned scientists, an exhibition that originated in London is set to open April 10 at the Montreal Science Center explores ideas on what aliens might look like, taking into consideration biology, astronomy, and the laws of physics and chemistry. The main attraction of the exhibition are alien forms envisioned by the scientists to fit the specific characteristics of two planets, such as carbon content, the temperature, the type of atmosphere.

The planets are about the same size as Earth, says Simon Conway Morris, a Cambridge evolutionary biologist who took a lead role in the exhibition, first presented in London, England, in 2006.

The planet supports life even though the star it orbits is much cooler than our sun. It does so by orbiting very closely, so close that the star's gravitational pull prevents Aurelia from spinning. One-half of the planet is always dark, the other always day.

The top predator on Aurelia is the bipedal gulphog, which has a long neck and a claw-like beak, and stands 4.5 meters tall. It might feed on six-legged mudpods that scurry on the ground, hide in burrows, and swim like crocodiles. There are also stinger fans, which look like plants but are actually animals that use tentacles to capture a weak star's energy.

"Blue Moon" is a planet more like Earth, but with much more oxygen and carbon dioxide in the atmosphere, allowing both plants and animals to grow bigger than on Earth. The air is extremely dense, allowing all sorts of animals to fly, such as so-called sky whales, which have nine-metre wingspans and fly using echolocation. They hover above thick "pagoda" forests, which stand at an astonishing 1,000 meters.

There are distinct similarities to creatures on Earth. Conway Morris says that's no mistake. "My constraint," he explains, "is that I seem to think that life could only evolve in a number of limited directions" -a theory known as "convergent evolution," whereby similar physical attributes evolve from completely unrelated ancestors.

"From different starting points, you end up with very similar biological solutions," he says. The eye, for instance, is found in all sorts of unrelated creatures. The octopus and the human have each developed an eye that's similar in construction.

"What I find so fantastic, if we did meet an alien, we might first (express disgust). But those differences would turn out to be skin deep. While they might look quite different, in the details of its organization, we'd be impressed by terrestrial similarities."

The scientists believe that extraterrestrials would also be subject to the laws of evolution that have shaped life on this planet.

"If you don't have evolution, you're not going to get from a simple replicating thing to bacteria to complex life," says NASA's Michael Meyer. "I can't think of another way." Other assumptions were made, such as the fact both Aurelia and Blue Moon have oxygen to support life. "There is reasonable scientific speculation that you need oxygen to get complex life forms because the energy-usage rate is so much higher to maintain different kinds of cells working in cooperation," Meyer says.

Meyer notes that we didn't have an aerobic world until 2.8 billion years ago, roughly the time we began getting more complex organisms.

As scientific as these researchers' approach was, it doesn't deny some of Hollywood scific visions. For example, the terrifying queen in Ridley Scott's scifi classic, Alien, with the acid blood. Neither Meyer nor Conway Morris discount the possibility. Here on Earth, they point out, the African bombardier beetle can spray boiling hydrogen peroxide at enemies.

The final zone of the exhibition looks at our attempts to communicate with aliens, largely through the SETI project, listening to radio waves, hoping for contact.

There is no hint at positing the existence of intelligent life, just the existence of "something."
Meyer's bet is based on simple math: "There are 100 billion stars in our galaxy. And there are 100 billion galaxies," he says. "That's a pretty large number – so there's got to be something out there."

Real forms of life that exist on Earth in extreme environments – under extreme pressure at the bottom of the ocean, or in extremely high temperatures, or acidic conditions – offer clues to the real forms that alien life might take. A few years ago, for example, scientists discovered a single-celled extremophile at a volcanic vent two kilometers under the sea, at 121 degrees C. At those depths, they need no sunlight. Researchers suggest they could survive on a planet that is habitually dark.

Posted by Casey Kazan.

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Research could lead to sharks predicting weather

Ground-breaking research which could lead to sharks being used to predict the weather has been carried out at Aberdeen’s National Hyperbaric Centre.
Marine Biology student Lauren Smith is close to completing her PhD studies into the pressure sensing abilities of the species. She used the University of Aberdeen altitude chamber at the Ashgrove Road West centre to test her theories.

Lauren's research, which has taken her to the glamorous surroundings of the Bahamas, was carried out in the wild on lemon sharks. She used their smaller, near relations – the lesser spotted dogfish (also known as the small spotted catshark) – for her research at a chamber in the centre.

It is thought the work being carried out by the 24-year-old University of Aberdeen student is the first of its kind to attempt to test the pressure theory.

It was prompted by an earlier shark habitat study in Florida, which coincided with the arrival of Hurricane Gabrielle in 2001, when observations suggested that juvenile blacktip sharks moved into deeper water in association with the approaching storm.

If Lauren's studies prove the theory, scientists in the future could conceivably monitor the behaviour of sharks to anticipate severe weather fronts.

Said Lauren: "I've always been keen on travelling and diving and this led me to an interest in sharks. I was delighted to have been able to explore this area for my PhD, particularly as it's the first time it's really been explored fully.

"I'm also extremely fortunate to have the University of Aberdeen facilities at the National Hyperbaric Centre right on the doorstep. How many other students get the chance to put a shark in a chamber to study its behaviour!

She said: "Who can say if this could lead to sharks predicting weather fronts, there's so much more we need to understand. But it certainly opens the way to more research."

David Smith, Managing Director of the National Hyperbaric Centre said: "Lauren's ground-breaking work again underlines the diversity of work and research which goes on at the centre, in this case at the University of Aberdeen chamber. We look forward with interest to the publication of her findings."

Both Lauren and the NHC stress that there is no question of the dogfish being harmed in any way by the research. The changes in pressure mimic the pressure changes experienced in and around the ocean, caused by weather fronts, and the protocol was approved by the Home Office.

Lauren, who's originally from West Bromwich and completed her first degree (BSc Hons) in Marine Biology and Coastal Ecology at Plymouth University, studied shark behaviour in the wild at the Bimini Biological Field Station in the Bahamas.

It has been established that a shark senses pressure using hair cells in its vestibular system – a mechanism discovered by Dr Peter Fraser, Lauren's supervisor at the University of Aberdeen.

Work at the Bimini Shark Lab enabled her to observe shark behaviour by placing data logging tags to record pressure and temperature on juvenile lemon sharks, while also tracking them using acoustic tags and GPS technology. This let her determine the exact movements of the juveniles, the first time hydrostatic pressure sensing of sharks in situ has been approached in this way.

She was also able to help on existing projects at the Bimini shark lab, which involved catching larger sharks – Tigers, Bulls, Blacktips, Nurse and Caribbean Reef sharks - and carrying out exercises like measurements and tagging for ID purposes.

Said Lauren: "It was incredible to do this with these large sharks - the largest was a 13ft tiger which is more than double my length! To be out there, enjoying the Bahamian lifestyle and to get to see, handle and discuss sharks every single day really was a dream come true."

Back at base in Aberdeen, she was able to study the effects of tidal and temperature changes on dogfish in the aquarium at the Zoology building. She was pleased to find she could also test the pressure theory by recreating weather conditions at the University of Aberdeen chamber at the National Hyperbaric Centre.

Lauren's academic travels have also taken her to Boston in the US to present a paper on animal navigation at a meeting of the Institute of Navigation, and she will be travelling to London this summer when the Aberdeen University work from Dr Fraser's laboratory on balance and hydrostatic pressure reception will feature in the Royal Society Summer Science Exhibition.

She's due to complete her PhD and prepare papers for publication later this year and will be looking for a job which will give her the chance to expand her experience of shark research.

* The National Hyperbaric Centre began as a Scottish Development Agency project and was acquired in 2005 by an independent company led by entrepreneur David Smith.

Since then its turnover has soared and the workforce has trebled, with the centre working on projects as diverse as this zoological study, to pressure testing ultra-deep offshore equipment and treating medical and diving emergency patients.

It recently celebrated its 20th anniversary with a multi-million pound plan to build the world's largest and deepest test chamber. The project, which could cost up to £10 million, would allow the centre to test subsea equipment to a depth of more than 3 miles.

ENDS


Notes to Editors:

Issued by the Communications Team, Office of External Affairs, University of Aberdeen, King's College, Aberdeen. Tel: (01224) 272014.

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Unlocking The Psychology Of Snake And Spider Phobias

Hundreds of thousands of people count snakes and spiders among their fears, and while scientists have previously assumed we possess an evolutionary predisposition to fear the unpopular animals, researchers at UQ's School of Psychology seem to have proved otherwise. (Credit: iStockphoto/Holger Gogolin)

Queensland researchers have unlocked new evidence that could help them get to the bottom of our most common phobias and their causes.

Hundreds of thousands of people count snakes and spiders among their fears, and while scientists have previously assumed we possess an evolutionary predisposition to fear the unpopular animals, researchers at UQ's School of Psychology may have proved otherwise.

According to Dr Helena Purkis, the results of the UQ study could provide an unprecedented insight into just why the creepy creatures are so widely feared.

“Previous research shows we react differently to snakes and spiders than to other stimuli, such as flowers or mushrooms, or even other dangerous animals….or cars and guns, which are also much more dangerous,” Dr Purkis said.

“[In the past, this] has been explained by saying that people are predisposed by evolution to fear certain things, such as snakes and spiders, that would have been dangerous to our ancestors.

“[However], people tend to be exposed to a lot of negative information regarding snakes and spiders, and we argue this makes them more likely to be associated with phobia.”

In the study, researchers compared the responses to stimuli of participants with no particular experience with snakes and spiders, to that of snake and spider experts.

“Previous research has argued that snakes and spiders attract preferential attention (they capture attention very quickly) and that during this early processing a negative (fear) response is generated… as an implicit and indexed subconscious [action],” Dr Purkis said.

“We showed that although everyone preferentially attends to snakes or spiders in the environment as they are potentially dangerous, only inexperienced participants display a negative response.”

The study is the first to establish a clear difference between preferential attention and the accompanying emotional response: that is, that you can preferentially attend to something without a negative emotional response being elicited.

Dr Purkis said the findings could significantly increase understanding about the basic cognitive and emotional processes involved in the acquisition and maintenance of fear.

“If we understand the relationship between preferential attention and emotion it will help us understand how a stimulus goes from being perceived as potentially dangerous, to eliciting an emotional response and to being associated with phobia,” she said.

“[This] could give us some information about the way people need to deal with snakes and spiders in order to minimise negative emotional responses.”

Researchers are now planning a follow-up study, which will test their theory that love and fear, or phobia, involve the same basic attention mechanism.

“We are interested in testing animal stimuli for animal lovers to see whether these stimuli, a dog for a breeder for instance, have access to preferential attention [in the same way as snakes and spiders do for those with phobias of them].

“I am also interested in the difference that we saw in our previous work between preferential attention, and the emotional response that is elicited after this initial processing."

The study calls for volunteers who work with or own dogs, cats, horses, cattle, snakes and spiders and also general members of the public who will form a control group.

“I also need people who are allergic to dogs or cats, people who are apprehensive of snakes and spiders, and people who have no fear of snakes and spiders but don't explicitly work with them,” Dr Purkis said.

“[Additionally, we're looking to get in touch with] people who are willing to have their pets (dogs, cats, horses, cattle, snakes, spiders) photographed for use as experimental stimuli.”

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The Science, History and How to of Contagious Laughter

What makes us fall in love? Is it lust, mutual interests, shared life goals, or something much more intangible? Recent research suggests the latter.

Researchers have only recently discovered an olfactory nerve which they believe is the route through which pheromones are processed. Nerve “O,” as it is called, slipped under the radar for many years because it is so tiny. However, when the nerve was discovered in a whale, scientists surmised that this little nerve might be found in humans as well. And it was!

So what is the role of Nerve “O”? Nerve “O” has endings in the nasal cavity, but the fibers go directly to the sexual regions of the brain. Indeed, these endings entirely bypass the olfactory cortex! Hence we know the role of Nerve “O” is not to consciously smell, but to identify sexual cues from our potential partners.

What sexual cues do our scents give off? For one thing, we are more likely to be attracted to people whose scent is dissimilar to our own. Family members often share similar chemicals, so our attraction to differing chemical makeup suggest that sexual cues evolved to protect close family members from procreating together. On the other hand, pregnant women have been shown to be more drawn to people with similar chemical makeup, which might be due to the fact that during this crucial time, women are more apt to seek out family members than potential mates.

Research has also shown that these unconscious cues processed in Nerve “O” can make or break a relationship. Couples who have high levels of chemicals in common are more likely to encounter fertility issues, miscarriage and infidelity. The more dissimilar you and your partner’s chemical makeup, the better chance you will have at successfully procreating and staying together.

So how can you create the scent which will keep you and your partner in the land of happily ever after? Unfortunately, you can’t. Perfumes and colognes can’t fool Nerve “O” — the scents which humans and animals are attracted to are intangible and instinctive. Even the most expensive designer perfume can’t fool Mother Nature. When it comes to sexual attraction, it seems you really have to leave things in the air!

However, if you are taking a hormonal contraceptive, you might be bucking an evolutionary tide. Women who are on the pill are more likely to be attracted to men with similar chemical makeup — most likely because their bodies are fooling them into believing they are pregnant, and so much like actual pregnant women, their Nerve “O” leads them to kin and not mates. So if you were on the pill when you met your mate, you might experience a diminishing attraction when you cease taking it.

Only time will tell what role Nerve “O” plays in future sex research, but one thing is for sure: When it comes to true love, follow your nose!

Dr. Laura Berman is the director of the Berman Center in Chicago, a specialized health care facility dedicated to helping women and couples find fulfilling sex lives and enriched relationships. She is also an assistant clinical professor of OB-GYN and psychiatry at the Feinberg School of Medicine at Northwestern University. She has been working as a sex educator, researcher and therapist for 18 years.

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