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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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Solar wind strips off water from Venus

September 17, 2009 By admin Leave a Comment

Washington, September 16 (ANI): Observations by the European Space Agency’s (ESA’s) Venus Express mission have provided strong new evidence that the solar wind has stripped away significant quantities of water from Earth’s twin planet Venus.

The SPICAV and VIRTIS instruments carried by the spacecraft have been used to measure concentrations of water vapor in the Venusian atmosphere at altitudes ranging from the lowest 10 km up to 110 km, high above the cloud tops.

Studies led by scientists from Belgium and Russia have found that the ratio of heavy water, which contains the isotope deuterium instead of hydrogen, to normal water is nearly twice as high above the clouds compared to its value in the lower atmosphere.

According to Dr. Emmanuel Marcq of the LATMOS laboratory in France, “Water vapor is a very rare species in the Venusian atmosphere: if it were in liquid form now, it would cover the surface of Venus with just a few centimeters of water. However, we believe Venus once had large volumes of water that have since escaped into space or stripped away by the solar wind.”

“These results from Venus Express demonstrate that the heavier water containing deuterium has not been able to escape Venus’s gravity as easily as normal H2O. This enrichment of heavy water provides strong evidence that water loss is occurring in the upper atmosphere and that Venus was probably more humid and Earth-like in the distant past,” he said.

Other studies by groups at the LESIA laboratory and the University of Oxford show that concentrations of water vapor decline from around 44 parts per million in the hot lower atmosphere to 25 parts per million at an altitude of 30-40 km.

At this level, the amounts of water vapor vary according to the overlying sulfuric acid cloud cover, with regions of thicker cloud containing less water vapor. (ANI)

Filed Under: Science News Tagged With: altitudes, centimeters, cloud cover, cloud tops, deuterium, european space agency, Heavy Water, high above the clouds, new evidence, Planet Venus, Rare Species, september 16, Solar Wind, twin planet, university of oxford, upper atmosphere, venusian atmosphere, virtis, water loss, water vapor

New evidence points towards recent ice age on Mars

August 28, 2009 By admin Leave a Comment

Washington, August 28 (ANI): In a new research, scientists have found evidence on the Martian terrain that points towards a recent ice age on the Red Planet.

The research, by Samuel C. Schon and James W. Head from the Department of Geological Sciences, Brown University, was carried out to explain the distribution of ice in the near subsurface at middle to high latitudes on Mars.

Two hypotheses emerged out of the research.

While one theory suggested diffusion of water vapor into porous regolith, the other indicated atmospheric deposition of ice, snow, and dust during recent ice ages.

To determine which of these hypotheses is correct, Schon and his team used data from the High Resolution Imaging Science Experiment (HiRISE) to examine the structure of exposed subsurface mid-latitude Martian terrain.

The researchers observed that the terrain is characterized by layered deposits multiple meters thick that stretch over many hundreds of meters.

They suggest that climate variations are most likely the source of this stratification.

The layers probably formed as dust, ice, and snow were deposited on the ground during recent ice ages, which occurred during periods when the tilt of Mars’s axis of rotation was higher than usual.

Vapor diffusion would be unlikely to result in the observed layered structure, according to the researchers.

They said that the observations also suggest that significant subsurface ice may remain in the 30 – 50 degrees mid-latitude regions. (ANI)

Filed Under: Science News Tagged With: atmospheric deposition, axis of rotation, brown university, Climate Variations, evidence points, geological sciences, High Latitudes, High Resolution Imaging, High Resolution Imaging Science Experiment, Hypotheses, imaging science, Latitude Regions, martian terrain, Mid Latitude, new evidence, red planet, research scientists, stratification, vapor diffusion, water vapor

Scientists confirm 1908 Tunguska explosion was caused by a comet

June 27, 2009 By admin Leave a Comment

Washington, June 25 (ANI): A new research has confirmed that the mysterious 1908 Tunguska explosion that leveled 830 square miles of Siberian forest was almost certainly caused by a comet entering the Earth’s atmosphere.

The research connects the two events by what followed each about a day later: brilliant, night-visible clouds, or noctilucent clouds, that are made up of ice particles and only form at very high altitudes and in extremely cold temperatures.

“It’s almost like putting together a 100-year-old murder mystery,” said Michael Kelley, the James A. Friend Family Distinguished Professor of Engineering at Cornell, who led the research team.

“The evidence is pretty strong that the Earth was hit by a comet in 1908,” he added.

Previous speculation had ranged from comets to meteors.

The researchers contend that the massive amount of water vapor spewed into the atmosphere by the comet’s icy nucleus was caught up in swirling eddies with tremendous energy by a process called two-dimensional turbulence, which explains why the noctilucent clouds formed a day later many thousands of miles away.

Noctilucent clouds are the Earth’s highest clouds, forming naturally in the mesosphere at about 55 miles over the polar regions during the summer months when the mesosphere is around minus 117 degrees Celsius.

The conclusion that a comet was behind the Tunguska Explosion was supported by an unlikely source: the exhaust plume from the NASA space shuttle launched a century later.

According to the researchers, the space shuttle exhaust plume resembled the comet’s action.

A single space shuttle flight injects 300 metric tons of water vapor into the Earth’s thermosphere, and the water particles have been found to travel to the Arctic and Antarctic regions, where they form the clouds after settling into the mesosphere.

Kelley and collaborators saw the noctilucent cloud phenomenon days after the space shuttle Endeavour (STS-118) launched on August 8, 2007.

Following the 1908 explosion, known as the Tunguska Event, the night skies shone brightly for several days across Europe, particularly Great Britain – more than 3,000 miles away.

Kelley said he became intrigued by the historical eyewitness accounts of the aftermath, and concluded that the bright skies must have been the result of noctilucent clouds.

The comet would have started to break up at about the same altitude as the release of the exhaust plume from the space shuttle following launch.

In both cases, water vapor was injected into the atmosphere.

According to scientists, the water vapor traveled so far without scattering and diffusing because it got caught in counter-rotating eddies with extreme energy, which made it travel close to 300 feet per second. (ANI)

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Cyclones can feed global warming by spurting ice into stratosphere

April 21, 2009 By admin Leave a Comment

Washington, April 21 (ANI): Scientists at Harvard University, US, have found that tropical cyclones readily inject ice far into the stratosphere, possibly feeding global warming.

The finding provides more evidence of the intertwining of severe weather and global warming by demonstrating a mechanism by which storms could drive climate change.

Many scientists now believe that global warming, in turn, is likely to increase the severity of tropical cyclones.

“Since water vapor is an important greenhouse gas, an increase of water vapor in the stratosphere would warm the Earth’s surface,” said David M. Romps, a research associate in Harvard’s Department of Earth and Planetary Science.

“Our finding that tropical cyclones are responsible for many of the clouds in the stratosphere opens up the possibility that these storms could affect global climate, in addition to the oft-mentioned possibility of climate change affecting the frequency and intensity of tropical cyclones,” he added.

Romps and co-author Zhiming Kuang, assistant professor of climate science in Harvard’s Faculty of Arts and Sciences, were intrigued by earlier data suggesting that the amount of water vapor in the stratosphere has grown by roughly 50 percent over the past 50 years.

Scientists are currently unsure why this increase has occurred.

The Harvard researchers sought to examine the possibility that tropical cyclones might have contributed by sending a large fraction of their clouds into the stratosphere.

Using infrared satellite data gathered from 1983 to 2006, Romps and Kuang analyzed towering cloud tops associated with thousands of tropical cyclones, many of them near the Philippines, Mexico, and Central America.

Their analysis demonstrated that in a cyclone, narrow plumes of miles-tall storm clouds can rise so explosively through the atmosphere that they often push into the stratosphere.

Romps and Kuang found that tropical cyclones are twice as likely as other storms to punch into the normally cloud-free stratosphere, and four times as likely to inject ice deep into the stratosphere.

According to the researchers, if very deep clouds, such as those in a tropical cyclone that can rise through the atmosphere at speeds of up to 40 miles per hour, can punch through the tropopause, they can deposit their ice in the warmer overlying stratosphere, where it then evaporates.

“This suggests that tropical cyclones could play an important role in setting the humidity of the stratosphere,” said Romps and Kuang. (ANI)

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Liquid saltwater on Mars detected by NASA’s Phoenix Lander

March 18, 2009 By admin Leave a Comment

Washington, March 18 (ANI): A new analysis by a group of mission scientists has determined that salty, liquid water has been detected on a leg of the Mars Phoenix Lander and therefore could be present at other locations on the Red Planet.

This is the first time liquid water has been detected and photographed outside the Earth.

“A large number of independent physical and thermodynamical evidence shows that saline water may actually be common on Mars,” said Nilton Renno, a professor in the U-M Department of Atmospheric, Oceanic and Space Sciences and a co-investigator on the Phoenix mission.

“Liquid water is an essential ingredient for life. This discovery has important implications to many areas of planetary exploration, including the habitability of Mars,” he added.

Previously, scientists believed that water existed on Mars only as ice or water vapor because of the planet’s low temperature and atmospheric pressure.

They thought that ice in the Red Planet’s current climate could sublimate, or vaporize, but they didn’t think it could melt.

This analysis shows how that assumption may be incorrect.

“Temperature fluctuation in the arctic region of Mars where Phoenix landed and salts in the soil could create pockets of water too salty to freeze in the climate of the landing site,” Renno said.

Photos of one of the Lander’s legs show droplets that grew during the polar summer.

Based on the temperature of the leg and the presence of large amounts of “perchlorate” salts detected in the soil, scientists believe the droplets were most likely salty liquid water and mud that splashed on the spacecraft when it touched down.

The Lander was guided down by rockets whose exhaust melted the top layer of ice below a thin sheet of soil.

“Some of the mud droplets that splashed on the Lander’s leg appear to have grown by absorbing water from the atmosphere,” Renno said.

Images suggest that some of the droplets darkened, then moved and merged – physical evidence that they were liquid.

Thermodynamic calculations offer additional evidence that salty liquid water can exist where Phoenix landed and elsewhere on Mars.

The calculations also predict a droplet growth rate that is consistent with what was observed. (ANI)

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New evidence points towards recent ice age on Mars

Scientists confirm 1908 Tunguska explosion was caused by a comet

Liquid saltwater on Mars detected by NASA’s Phoenix Lander

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