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How life might evolve with “exotic” biochemistry and solvents

September 19, 2009 By admin Leave a Comment

London, September 18 (ANI): Scientists at a new interdisciplinary research group in Austria are working to uncover how life might evolve with “exotic” biochemistry and solvents, such as sulfuric acid instead of water.

The research group for Alternative Solvents as a Basis for Life Supporting Zones in (Exo-) Planetary Systems was established by the University of Vienna.

Traditionally, planets that might sustain life are looked for in the ‘habitable zone’, the region around a star in which Earth-like planets with carbon dioxide, water vapor and nitrogen atmospheres could maintain liquid water on their surfaces.

Consequently, scientists have been looking for biomarkers produced by extraterrestrial life with metabolisms resembling the terrestrial ones, where water is used as a solvent and the building blocks of life, amino acids, are based on carbon and oxygen.

However, these may not be the only conditions under which life could evolve.

“It is time to make a radical change in our present geocentric mindset for life as we know it on Earth,” said scientist Johannes Leitner.

“Even though this is the only kind of life we know, it cannot be ruled out that life forms have evolved somewhere that neither rely on water nor on a carbon and oxygen based metabolism,” he added.

One requirement for a life-supporting solvent is that it remains liquid over a large temperature range.

Water is liquid between 0 degree Celsius and 100 degrees C, but other solvents exist which are liquid over more than 200 degrees C.

Such a solvent would allow an ocean on a planet closer to the central star.

The reverse scenario is also possible. A liquid ocean of ammonia could exist much further from a star.

Furthermore, sulfuric acid can be found within the cloud layers of Venus and it is now known that lakes of methane/ethane cover parts of the surface of the Saturnian satellite Titan.

Consequently, the discussion on potential life and the best strategies for its detection is ongoing and not only limited to exoplanets and habitable zones.

The newly established research group at the University of Vienna, together with international collaborators, will investigate the properties of a range of solvents other than water, including their abundance in space, thermal and biochemical characteristics as well as their ability to support the origin and evolution of life supporting metabolisms. (ANI)

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Scientists unravel chemistry of Titan’s hazy atmosphere

September 17, 2009 By admin Leave a Comment

Washington, September 16 (ANI): In a new research, a team of scientists has unraveled the chemical evolution of the orange-brownish colored atmosphere of Saturn’s moon Titan, the only solar system body besides Venus and Earth with a solid surface and thick atmosphere.

Scientists at University of Hawai’i at Manoa carried out the research.

The UH Manoa team, including Xibin Gu and Seol Kim, conducted simulation experiments mimicking the chemical reactions in Titan’s atmosphere utilizing crossed molecular beams in which the consequence of a single collision between molecules can be followed.

The team’s experiments indicate that triacetylene can be formed by a single collision of a “radical” ethynyl molecule and a diacetylene molecule.

An ethynyl radical is produced in Titan’s atmosphere by the photodissociation of acetylene by ultraviolet light.

Photodissociation is a process in which a chemical compound is broken down by photons.

“Surprisingly, the photochemical models show inconsistent mechanisms for the production of polyynes,” said Kaiser, who is the principal investigator of this study.

The mechanism involved in the formation of triacetylene, was also confirmed by accompanying theoretical calculations by Alexander Mebel, a theoretical chemist at Florida International University.

These theoretical computations also provide the 3D distribution of electrons in atoms and thus the overall energy level of a molecule.

To apply these findings to the real atmosphere of Titan, Danie Liang and Yuk Yung, planetary scientists at Taiwan’s Academia Sinica and California Institute of Technology (Caltech), respectively, performed photochemical modeling studies of Titan’s atmosphere.

All data together suggest that triacetylene may serve as a building block to form more complex and longer polyynes and produce potential precursors for the aerosol-based layers of haze surrounding Titan.

The study demonstrated for the first time that a sensible combination of laboratory simulation experiments with theory and modeling studies can shed light on decade old unsolved problems crucial to understand the origin and chemical evolution of the solar system.

The researchers hope to unravel next the mystery of the missing ethane lakes on Titan – postulated to exist for half a century, but not detected conclusively within the framework of the Cassini-Huygens mission.

In the future, the UH Manoa team will combine the research results with terrestrial-based observations of Titan’s atmosphere. (ANI)

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Largest lake on Saturn’s moon Titan found to be as smooth as a mirror

August 22, 2009 By admin Leave a Comment

London, August 22 (ANI): A new study has shown that the largest lake on Saturn’s moon Titan is as smooth as a mirror, varying in height by less than 3 millimeters, and good enough for skipping rocks on it.

According to a report in New Scientist, the find, based on new radar observations, adds to a deluge of evidence that the moon’s lakes are indeed filled with liquid, rather than dried mud.

“Unless you actually poured concrete and spread it really, really smoothly, you’d never see something like that on Earth,” said team member Howard Zebker of Stanford University.

Astronomers have waffled on whether Saturn’s largest moon is dry or wet, but the bulk of the evidence points to liquid lakes.

The radar on the Cassini spacecraft, which arrived at Saturn in 2004, turned up dark splotches at Titan’s poles.

The darkness in radar indicates those regions are very smooth, like the signal expected from the surface of a liquid lake.

Spectral data also showed that the apparent lakes seem to be filled with methane and ethane, which would be liquid on Titan’s frigid surface, and “geomorphologically, they just look like lakes,” Zebker said.

But, previous radar observations viewed the apparent lakes at an angle, and therefore did not see bright radar glints reflected back from their surface, leaving open the possibility that the features were dry lake beds or patches of soot.

Now, researchers report seeing just that signal.

In December last year, Cassini pointed its radar straight down over Titan’s largest lake, Ontario Lacus, which spans 235 kilometres at the moon’s south pole.

The reflected signal was so strong, it maxed out the probe’s receiver.

The radar echoes revealed a surface covering thousands of square metres whose height varies by less than 3 millimetres – 10 times as flat as previous measurements were able to reveal.

“It’s very hard to imagine a solid surface that is smooth on the order of millimeters,” lead author Lauren Wye of Stanford told New Scientist.

This provides strong evidence that the lake is currently liquid, not dried mud.

“If you’ve ever walked outside and seen an area on the ground where there’s mud and the water dries up, even that is pretty flat – but you get cracks in the mud and pieces that curl up,” Zebker said. “You never see anything as smooth as what we’re inferring for Titan’s surface,” he added.

Confirming the presence of liquid on Titan adds to the long list of similarities between Titan and Earth. (ANI)

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Evidence points towards methane seeping from Arctic sea bed

August 19, 2009 By admin Leave a Comment

London, August 19 (ANI): A team of scientists has said that they have evidence that the powerful greenhouse gas methane is escaping from the Arctic sea bed.

According to a report by BBC News, researchers said this could be evidence of a predicted positive feedback effect of climate change.

As temperatures rise, the sea bed grows warmer and frozen water crystals in the sediment break down, allowing methane trapped inside them to escape.

The research team found that more than 250 plumes of methane bubbles are rising from the sea bed off Norway.

The joint British and German research team detected the bubbles using a type of sonar normally used to search for shoals of fish.

Once detected, the bubbles were sampled and tested for methane at a range of depths.

The team said that the methane was rising from an area of sea bed off West Spitsbergen, from depths between 150 and 400m.

The gas is normally trapped as “methane hydrate” in sediment under the ocean floor.

“Methane hydrate” is an ice-like substance composed of water and methane which is stable under conditions of high pressure and low temperature.

As temperatures rise, the hydrate breaks down. So, this new evidence shows that methane is stable at water depths greater than 400m off Spitsbergen.

However data collected over 30 years shows it was then stable at water depths as shallow as 360m.

Temperature records show that this area of the ocean has warmed by 1 degree Celsius during the same period.

According to the research team, this is the first time that this loss of stability associated with temperature rise has been observed during the current geological period.

Professor Tim Minshull of the National Oceanography Centre at Southampton told BBC News, “We already knew there was some methane hydrate in the ocean off Spitsbergen and that’s an area where climate change is happening rather faster than just about anywhere else in the world.” ethane gas rises from the sea bed in plumes of bubbles, with most of it dissolving before reaching the surface.

So far, scientists haven’t detected methane breaking the ocean surface, but they don’t rule out the possibility.

“There’s been an idea for a long time that if the oceans warm, methane might be released from hydrate beneath the sea floor and generate a positive greenhouse effect,” said Minshull. (ANI)

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Biphosphonates may prevent radiation-induced leukaemia

April 20, 2009 By admin Leave a Comment

Washington, Apr 20 (ANI): A new study has revealed that treatment with biphosphonates could prevent radiation-induced leukaemia.

Lead researcher Dr Alexandra Miller, a senior scientist at the Armed Forces Radiobiology Research Institute, said that the study will not only help military and space agency personnel exposed to risky levels of radiation, it will also be beneficial for civilian populations.

“It is possible, although not yet proven, that the compound we studied could have a general effect on leukemia associated with causes other than radiation, such as age, which is much more common,” said Miller.

During the study, the research team studied biphosphonates known to scientists as ethane-1-hydroxy-1, 1-biphosphonate (EHBP) and carballylic amido bis phosphonic acid (CAPBP).

Biphosphonates have emerged as an attractive chemopreventive agent due to earlier research that suggests they prevent bone metastasis and because they have an ability to remove uranium from the body.

The researchers irradiated laboratory mice at 3.5 Gy and found that all of the mice who were not treated with either EHBP or CAPBP developed leukemia.

By contrast, if they were treated with six doses of EHBP only 75 percent of mice developed leukemia. Similarly, only 65 percent of mice treated with CAPBP developed leukemia.

The study was presented at the American Association for Cancer Research 100th Annual Meeting 2009. (ANI)

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Virtual maps provide bird’s-eye view of Titan’s Earth-like landscapes

March 25, 2009 By admin Leave a Comment

Washington, March 25 (ANI): Scientists have made new virtual topographic maps of Saturn’s moon Titan, which provide a bird’s-eye view its Earth-like landscapes.

Cassini radar team member Randy Kirk with the Astrogeology Science Center at the U.S. Geological Survey in Flagstaff, Arizona, created the maps.

He used some of the 20 or so areas where two or more overlapping radar measurements were obtained during 19 Titan flybys.

These stereo overlaps cover close to two percent of Titan’s surface.

The process of making topographic maps from them is just beginning, but the results already reveal some of the diversity of Titan’s geologic features.

The new flyover maps show, for the first time, the 3-D topography and height of the 1,200-meter (4,000-foot) mountain tops, the north polar lake country, the vast dunes more than 100 meters (300 feet) high that crisscross the moon, and the thick flows that may have oozed from possible ice volcanoes.

“These flyovers let you take in the bird’s-eye sweeping views of Titan, the next best thing to being there,” said Kirk.

“We’ve mapped many kinds of features, and some of them remind me of Earth. Big seas, small lakes, rivers, dry river channels, mountains and sand dunes with hills poking out of them, lava flows,” he added.

The maps show some features that may be volcanic flows. These flows meander across a shallow basin in the mountains.

One area suspected to be an ice volcano, Ganesa Macula, does not appear to be a volcanic dome. It may still have originated as a volcano, but it’s too soon to know for sure.

“It could be a volcanic feature, a crater, or something else that has just been heavily eroded,” said Kirk.

The stereo coverage includes a large portion of Titan’s north polar lakes of liquid ethane and methane. Based on these topographical models, scientists are better able to determine the depth of lakes.

The highest areas surrounding the lakes are some 1,200 meters (about 4,000 feet) above the shoreline.

By comparing terrain around Earth to the Titan lakes, scientists estimate their depth is likely about 100 meters (300 feet) or less.

More 3-D mapping of these lakes will help refine these depth estimates and determine the volume of liquid hydrocarbons that exist on Titan.

This information is important because these liquids evaporate and create Titan’s atmosphere. Understanding this methane cycle can provide clues to Titan’s weather and climate. (ANI)

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Sun-powered device converts CO2 into fuel

February 19, 2009 By admin Leave a Comment

London, Feb 19 (ANI): A team of scientists has developed a device that houses an array of nanotubes, that is able to convert a mixture of carbon dioxide and water vapour into natural gas at unprecedented rates.

According to a report in New Scientist, Craig Grimes, from Pennsylvania State University, and his team came up with the device.

“Such devices offer a new way to take carbon dioxide from the atmosphere and convert it into fuel or other chemicals to cut the effect of fossil fuel emissions on global climate,” said Grimes.

Although other research groups have developed methods for converting carbon dioxide into organic compounds like methane, often using titanium-dioxide nanoparticles as catalysts, they have needed ultraviolet light to power the reactions.

The researchers’ breakthrough has been to develop a method that works with the wider range of visible frequencies within sunlight.

The team found it could enhance the catalytic abilities of titanium dioxide by forming it into nanotubes each around 135 nanometres wide and 40 microns long to increase surface area.

Coating the nanotubes with catalytic copper and platinum particles also boosted their activity.

The researchers housed a 2-centimetre-square section of material bristling with the tubes inside a metal chamber with a quartz window.

They then pumped in a mixture of carbon dioxide and water vapour and placed it in sunlight for three hours.

The energy provided by the sunlight transformed the carbon dioxide and water vapour into methane and related organic compounds, such as ethane and propane, at rates as high as 160 microlitres an hour per gram of nanotubes.

This is 20 times higher than published results achieved using any previous method, but still too low to be immediately practical.

If the reaction is halted early the device produces a mixture of carbon monoxide and hydrogen known as syngas, which can be converted into diesel.

“We are now working on uniformly sensitising the entire nanotube array surface with copper nanoparticles, which should dramatically increase conversion rates,” said Grimes, by at least two orders of magnitude for a given area of tubes. (ANI)

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