1000 ancient hieroglyphic rock paintings found in east-central China

May 7, 2010 By Leave a Comment

New Delhi, May 7 (ANI): Ma Baoguang, a Chinese archaeologist, recently found 1,000 hieroglyphic rock paintings in Yangce Town, Biyang County of east-central China”s Henan province.

Ma and a group of students were there on a dig and found the paintings over an area of 5 square kilometres.

One of the most rare and valuable findings is a Juci Mountain-style rock – a large cambered stone, is 8 meters long and 3.7 meters wide. There are more than 500 small craters of different sizes on the surface of the stone and several relatively larger craters that are 13 to 20 centimeters in diameter and three to seven centimeters in depth. Various lines, forming a very large ancient diagram, connect these craters.

“It is quite incredible that a large stone goat carries ”Hetu and Luoshu” (map of the Yellow River and the book of the Luo River) on its back,” People’s Daily Online quoted Ma as saying. (ANI)

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Iceland’s erupting volcano forms new craters

April 1, 2010 By Leave a Comment

Thu, Apr 1 09:01 AM

A volcano blasting steam and ash into the atmosphere in the south of Iceland formed new craters spewing lava on Wednesday, Icelandic radio said.

The volcano under the Eyjafjallajokull glacier began erupting 10 days ago, forcing hundreds of people to leave the area and leading authorities to divert flights.

A new fissure about 300 metres long opened up on Wednesday, state radio said. Geologists believe this could mean activity is moving further north, towards the nature reserve of Thorsmork, a popular tourist site.

Vidir Gardarsson of the Civil Defence in Reykjavik told the newspaper Morgonbladid the fissure was still expanding.

“We want to move people away from the area while we figure out what is going on,” he said. “This is a security measure while this evolves.”

Police estimate that about 25,000 people have visited the site in recent days.

Iceland lies on a volcanic hotspot in the Mid-Atlantic Ridge and is prone to eruptions, although most occur in sparsely populated areas and pose little danger to life or property. The last eruption took place in 2004.

Scientists had been monitoring the Eyjafjallajokull glacier, dormant since 1821, for signs of seismic activity but said there was little warning before the latest activity.

(Editing by Andrew Dobbie)

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Moon”s biggest crater exposes its hidden lower crust

March 5, 2010 By Leave a Comment

Washington, March 5 (ANI): Reports indicate that the biggest and deepest crater on the Moon can provide glimpses of the hidden lower crust of Earth”s natural satellite.

Shortly after the Moon formed, an asteroid smacked into its southern hemisphere and gouged out a truly enormous crater, the South Pole-Aitken basin, almost 1,500 miles across and more than five miles deep.

Asteroid bombardment over billions of years has left the lunar surface pockmarked with craters of all sizes, and covered with solidified lava, rubble, and dust.

Glimpses of the original surface, or crust, are rare, and views into the deep crust are rarer still.

Fortunately, a crater on the edge of the South Pole-Aitken basin may provide just such a view.

According to Noah Petro of NASA”s Goddard Space Flight Center in Greenbelt, Maryland, “We believe the central part of the Apollo Basin may expose a portion of the Moon”s lower crust. If correct, this may be one of just a few places on the Moon where we have a view into the deep lunar crust, because it”s not covered by volcanic material as many other such deep areas are.”

“Just as geologists can reconstruct Earth”s history by analyzing a cross-section of rock layers exposed by a canyon or a road cut, we can begin to understand the early lunar history by studying what”s being revealed in Apollo,” he said.

Petro and his team made the discovery with the Moon Mineralogy Mapper (M3), a NASA instrument on board India”s Chandrayaan-1 lunar-orbiting spacecraft.

Analysis of the light (spectra) in images from this instrument revealed that portions of the interior of Apollo have a similar composition to the impact melt in the South Pole-Aitken (SPA) basin.

As you go deeper into the Moon, the crust contains minerals have greater amounts of iron. When the Moon first formed, it was largely molten.

Minerals containing heavier elements, like iron, sank down toward the core, and minerals with lighter elements, like silicon, potassium, and sodium, floated to the top, forming the original lunar crust.

“The asteroid that created the SPA basin probably carved through the crust and perhaps into the upper mantle. The impact melt that solidified to form the central floor of SPA would have been a mixture of all those layers,” said Petro.

“We expect to see that it has slightly more iron than the bottom of Apollo, since it went deeper into the crust. This is what we found with M3,” he said.

“However, we also see that this area in Apollo has more iron than the surrounding lunar highlands, indicating Apollo has uncovered a layer of the lunar crust between what is typically seen on the surface and that in the deepest craters like SPA,” he added. (ANI)

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New evidence points towards water on Moon

September 19, 2009 By Leave a Comment

London, September 19 (ANI): Two separate lunar missions have found evidence which indicates that the polar regions of the moon are chock full of water-altered minerals.

According to a report in Nature News, early results from NASA’s Lunar Reconnaissance Orbiter (LRO), launched on June 18, are offering a wide array of watery signals.

The Moon, in fact, has water in all sorts of places: not just locked up in minerals, but scattered throughout the broken-up surface, and, potentially, in blocks or sheets of ice at depth.

“We are on the verge of a renaissance in our thinking about the poles of the Moon, including how water ice gets there,” said Anthony Colaprete, principal investigator for the Lunar Crater Observation and Sensing Satellite (LCROSS), which on October 9, will slam into a polar crater with the intention of ploughing up a plume of water ice for many telescopic eyes to see.

The initial LRO results confirm what was long suspected as a way for ice to stay trapped on the Moon for billions of years.

A thermal mapping instrument showed that permanently shadowed regions within deep polar craters are as cold as 35o Kelvin (-238o Celsius).

Project scientist Richard Vondrak said that they are the coldest spots in the Solar System – even colder than the surface of Pluto.

Variations in the flux of neutrons suggests variability in water content among craters.

But, the surprise comes from a different instrument on LRO, which counts slow-moving neutrons as a way of measuring hydrogen abundance in the top metre or so of the surface.

This hydrogen is often interpreted as a proxy for water ice, although it could also be molecular hydrogen or hydrogen trapped in other molecules.

The LRO instrument has already found a significant excess of hydrogen at the poles.

But, with added resolution, it is seeing surprising variability within the polar regions. Some of the craters appear enriched in hydrogen. Others are not.

Stranger still, some areas outside the crater walls, which were thought to get too hot for water to linger, show an excess of hydrogen.

Vondrak said this shows that the water could have arrived more recently, or that it can persist if buried as impacts till the lunar soil.

If the LCROSS impact spews up ice, it will eliminate the last vestiges of doubt about water on the Moon.

It could also start a new hunt: to find a record of impact events, such as water-rich comet strikes, that put the ice there in the first place. (ANI)

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New evidence points towards water on Moon

September 19, 2009 By Leave a Comment

London, September 19 (ANI): Two separate lunar missions have found evidence which indicates that the polar regions of the moon are chock full of water-altered minerals.

According to a report in Nature News, early results from NASA’s Lunar Reconnaissance Orbiter (LRO), launched on June 18, are offering a wide array of watery signals.

The Moon, in fact, has water in all sorts of places: not just locked up in minerals, but scattered throughout the broken-up surface, and, potentially, in blocks or sheets of ice at depth.

“We are on the verge of a renaissance in our thinking about the poles of the Moon, including how water ice gets there,” said Anthony Colaprete, principal investigator for the Lunar Crater Observation and Sensing Satellite (LCROSS), which on October 9, will slam into a polar crater with the intention of ploughing up a plume of water ice for many telescopic eyes to see.

The initial LRO results confirm what was long suspected as a way for ice to stay trapped on the Moon for billions of years.

A thermal mapping instrument showed that permanently shadowed regions within deep polar craters are as cold as 35o Kelvin (-238o Celsius).

Project scientist Richard Vondrak said that they are the coldest spots in the Solar System – even colder than the surface of Pluto.

Variations in the flux of neutrons suggests variability in water content among craters.

But, the surprise comes from a different instrument on LRO, which counts slow-moving neutrons as a way of measuring hydrogen abundance in the top metre or so of the surface.

This hydrogen is often interpreted as a proxy for water ice, although it could also be molecular hydrogen or hydrogen trapped in other molecules.

The LRO instrument has already found a significant excess of hydrogen at the poles.

But, with added resolution, it is seeing surprising variability within the polar regions. Some of the craters appear enriched in hydrogen. Others are not.

Stranger still, some areas outside the crater walls, which were thought to get too hot for water to linger, show an excess of hydrogen.

Vondrak said this shows that the water could have arrived more recently, or that it can persist if buried as impacts till the lunar soil.

If the LCROSS impact spews up ice, it will eliminate the last vestiges of doubt about water on the Moon.

It could also start a new hunt: to find a record of impact events, such as water-rich comet strikes, that put the ice there in the first place. (ANI)

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Cracks on Mars a result of evaporating lakes in ancient times

September 17, 2009 By Leave a Comment

Washington, September 16 (ANI): Networks of giant polygonal troughs etched across crater basins on Mars have been identified as desiccation cracks caused by evaporating lakes, providing further evidence of a warmer, wetter Martian past.

The findings were presented at the European Planetary Science Congress by PhD student M. Ramy El Maarry of the Max Planck Institute for Solar System Research.

The polygons are formed when long cracks in the surface of the Martian soil intersect.

El Maarry investigated networks of cracks inside 266 impact basins across the surface of Mars and observed polygons reaching up to 250 meters in diameter.

Polygonal troughs have been imaged by several recent missions but, until now, they have been attributed to thermal contractions in the Martian permafrost.

El Maarry created an analytical model to determine the depth and spacing of cracks caused by stresses building up through cooling in the Martian soil.

He found that polygons caused by thermal contraction could have a maximum diameter of only about 65 meters, much smaller than the troughs he was seeing in the craters.

“I got excited when I saw that the crater floor polygons seemed to be too large to be caused by thermal processes. I also saw that they resembled the desiccation cracks that we see on Earth in dried up lakes,” said El Maarry.

“The stresses that build up when liquids evaporate can cause deep cracks and polygons on the scale I was seeing in the craters,” he added.

El Maarry identified the crater floor polygons using images taken by the MOC camera on Mars Global Surveyor and the HiRISE and Context cameras on Mars Reconnaissance Orbiter.

The polygons in El Maarry’s survey had an average diameter of between 70 and 140 kilometers, with the width of the actual cracks ranging between 1 and 10 meters.

Evidence suggests that between 4.6 and 3.8 billion years ago, Mars was covered in significant amounts of water.

Rain and river water would have collected inside impact crater basins, creating lakes that may have existed for several thousand years before drying out.

However, according to El Maarry, in the northern hemisphere, some of the crater floor polygons could have been formed much more recently.

“When a meteorite impacts with the Martian surface, the heat can melt ice trapped beneath the Martian crust and create what we call a hydrothermal system. Liquid water can fill the crater to form a lake, covered in a thick layer of ice. Even under current climatic conditions, this may take many thousands of years to disappear, finally resulting in the desiccation patterns,” said El Maarry. (ANI)

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Craters on Vesta and Ceres could pinpoint Jupiter’s age

September 14, 2009 By Leave a Comment

Washington, September 14 (ANI): A new study that models the cratering history of Vesta and Ceres, which are the largest two objects in the asteroid belt, could help pinpoint when Jupiter began to form during the evolution of the early Solar System.

The study, carried out by scientists at the Italian National Institute for Astrophysics in Rome, explored the hypothesis that one or both objects formed during Jupiter’s formation by modeling their cratering histories during the birth of the giant planet.

Their simulation described Jupiter’s formation in three stages: an initial accretion of its core followed by a stage of rapid gas accretion.

This is, in turn, followed by a phase where the gas accretion slows down while the giant planet reaches its final mass.

During the last two phases, Jupiter’s gravitational pull starts to affect more and more distant objects.

For each of these phases, the team simulated how Jupiter affected the orbits of asteroids and comets from the inner and outer Solar System, and the likelihood of them being moved onto a collision path with Vesta or Ceres.

According to Dr. Diego Turrini, who presented the results of the study at the European Planetary Science Congress in Potsdam, Germany, “We found that the stage of Jupiter’s development made a big difference on the speed of impacts and the origin of potential impactors.”

“When Jupiter’s core approaches its critical mass, it causes a sharp increase in low-velocity impacts from small, rocky bodies orbiting nearby to Vesta and Ceres which lead to intense and uniform crater distribution patterns. These low-speed collisions may have helped Vesta and Ceres gather mass,” he said.

“Once Jupiter’s core has formed and the planet starts to rapidly accrete gas, it deflects more distant objects onto a collision course with Ceres and Vesta and the impacts become more energetic,” he added.

The third stage of Jupiter’s formation is complicated by a period known as the Late Heavy Bombardment, which occurred around 3.8 to 4.1 billion years ago.

During this time, a significant number of objects, rich in organic compounds, from the outer Solar System were injected on planet-crossing orbits with the giant planets and may have reached the Asteroid Belt.

In addition, Jupiter is thought to have migrated in its orbit around this time, which would have caused an addition flux of impactors on Vesta and Ceres.

The team will have an opportunity to confirm their results when NASA’s Dawn space mission reaches Vesta in 2011 and then flies on for a further rendezvous with Ceres in 2015. (ANI)

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India’s Chandrayaan-1 and NASA join hands to search for water on the moon

August 26, 2009 By Leave a Comment

London, August 26 (ANI): A joint collaboration between India’s Chandrayaan-1 and NASA’s Lunar Reconnaissance Orbiter, which are orbiting the moon, could turn up evidence for valuable lunar water.

Some scientists suspect water ice, which would be a precious resource for future explorers, may be trapped in permanently shadowed craters at the moon’s poles.

Water ice can be distinguished from other materials by the way its radar echoes vary according to the position of the listener.

In 1994, the US Clementine spacecraft bounced radar signals off the moon and found hints of the water-ice signature.

But, it listened for the reflections jointly with a radio observatory on Earth, and getting unambiguous evidence for water requires more closely spaced listening posts.

According to a report in New Scientist, a recent joint experiment involving the US and Indian space agencies has provided a unique opportunity to get that data.

“It’s a unique experiment that can only be conducted by two spacecraft in orbit at the same time,” said Jason Crusan of NASA headquarters in Washington, DC.

On August 20, NASA’s Lunar Reconnaissance Orbiter and Chandrayaan-1 were manoeuvred to within a few dozen kilometres of each other, which required close communication and coordination between NASA and the Indian Space Research Organisation (ISRO).

Once in proper formation, Chandrayaan-1 fired its radar beam at a crater near the moon’s north pole, while both spacecraft listened for the echoes.

Crusan said that scientists were still analyzing the data to make sure the experiment worked, but added that both spacecraft were in the right positions at the right time for it to go as planned.

This is probably the only time the two spacecraft will perform this kind of joint radar measurement, since LRO will soon move to a lower orbit than Chandrayaan-1 in order to begin its main observing phase.

But last week’s experiment marks a new level of space cooperation between the US and India.

“I hope this is a sign of the future for how we will do cooperative exploration,” Crusan said. “I think it’s a good first step,” he added. (ANI)

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IDPs identifying LTTE cadres in Lanka refugee camps: Army

May 25, 2009 By Leave a Comment

Colombo, May 25 (ANI): The spokesman of the Sri Lankan Army, Brigadier Udaya Nanayakkara, on Monday said that Internally Displaced Persons (IDPs) in welfare camps are identifying several former Tigers hiding among them and handing them over to the Army.

The Colombo Times quoted Brigadier Nanayakkara as saying that former Tigers have been taken in for questioning about the roles they played in the Tiger movement.

“Some of them will be indicted before the Courts depending on the roles they played in the Tiger movement, and some others will be sent for rehabilitation,” he added.

In all there are about 5000 former Tigers housed among civilians in the welfare camps, he claimed.

n several instances, former Tigers had been beaten up by civilians and hospitalized by the Army.

Meanwhile, another report has described Sri Lanka’s ‘no-fire zone’ as a place of utter devastation that it mocks its very name.

“It is hell unleashed in paradise. A glistening white beach packed with home made bunkers where civilians huddled to protect themselves from the shells that the government denies launching in the final weeks of the offensive. There are craters in the white sand; the charcoal-coloured scorch marks and bombed-out dwellings.”

No journalists, aid workers or independent observers had access to the zone until the weekend, when a small group of journalists accompanied the United Nations secretary-general, Ban Ki Moon, on a flight over the zone.

The UN believes that between 8,000 and 10,000 civilians have died in the conflict since the beginning of this year.

The government denies inflicting a single civilian death, blaming the Tigers for the shelling.

What happened inside the so-called ‘no-fire zone’ will not be the subject of any investigation in Sri Lanka, although the prime minister has called for a commission to investigate the arming and activities of the Tigers. (ANI)

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“Supergiant” asteroid shut down magnetic field of Mars

May 12, 2009 By Leave a Comment

Washington, May 12 (ANI): In a new research, scientists suggest that a “supergiant” asteroid several times larger than the one that likely killed the dinosaurs struck Mars with such force that it shut down the planet’s magnetic field.

Based on the number of large craters present, scientists think very early Mars suffered 15 or so giant impacts within a span of about a hundred million years.

Now, according to a report in National Geographic News, a new computer model suggests that Mars’s magnetic field may have been slowly weakened by four especially large impacts and then snuffed out completely by a fifth and final blow.

“That impact created the 2,000-mile-wide (3,300-kilometer-wide) Utopia crater, which dates back roughly 4.1 billion years,” said study team member James Roberts of the Johns Hopkins Applied Physics Lab in Maryland.

“It’s possible that the four earlier impacts set everything up, and the Utopia crater was the straw that broke camel’s back,” he added.

Earth has a magnetic field in part because of heat transfer between the planet’s rotating molten core and the relatively cooler mantle layer above it.

This temperature difference helps create what’s known as an electric dynamo, which keeps the magnetic field stable over time.

But when the solar system was first forming it went through a tumultuous time known as the Late Heavy Bombardment, in which several large asteroids-remnants of planetary formation-smashed into young Mars, Earth, Venus, and Mercury.

“This is about the time the Utopia crater was formed, and roughly the same time that scientists think the Martian magnetic field shut down,” said Roberts.

According to the new model, the Utopia impact injected so much heat into the Martian mantle that it drastically reduced the temperature difference driving the dynamo.

“If the mantle becomes too hot, it’s not able to cool the core as efficiently, and there is no magnetic field,” Roberts told National Geographic News.

Without a magnetic field, Mars was exposed to the full brunt of the solar wind, the continuous stream of charged particles emitted by the sun.

The solar wind could then have slowly eroded away Mars’s atmosphere until only a wispy envelope of gas remained.

Drastic climate change would have soon followed, helping to create the desiccated Mars we know today. (ANI)

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Revealing origin and evolution of planet Mercury

May 3, 2009 By Leave a Comment

Washington, May 1 (ANI): Scientists, using multispectral images obtained from the Messenger spacecraft, are trying to reveal the origin and evolution of the planet Mercury.

Mercury’s interior is thought to generally resemble that of the Earth and Mars. However, Mercury’s core is anomalously large leading to it sometimes being called the iron planet.

With its ancient craters and smooth plains both covered in a fine-grained gray soil (or regolith), the surface of Mercury superficially resembles the surface of the Moon.

Unlike Earth’s crust, which is constantly changing and evolving due to processes such as plate tectonics, the crust is relatively static on the Moon and Mercury.

The bulk of Mercury’s crust formed long ago and preserves a record of early events that shaped it and the subsequent forces that modified it.

“Mercury’s surface tells us something fundamental about how the planet formed and evolved,” said Brett Denevi, a postdoctoral research associate in the School of Earth and Space Exploration at Arizona State University.

“Some of the little evidence that we had prior to MESSENGER seemed to indicate that the composition of Mercury’s crust was similar to that of the Moon, leading to the presumption that it had formed in the same manner, with any volcanism that may have occurred being only a secondary component,” she said.

While the highlands on the Moon are thought to have formed as the result of a global magma ocean, where less dense minerals floated to the surface to form the crust, evidence now points to a mercurian crust that formed in a manner more similar to the crust of Mars than to that of the Moon.

Denevi’s research confirms that volcanism on Mercury was widespread, visible across nearly the entire planet, and that much of the crust may have formed in repeated volcanic eruptions.

Denevi, the lead author on the paper, processed and analyzed the images and spectra.

To help determine how much of Mercury’s surface was comprised of smooth plains, she constructed maps by observing overlapping and abutting relations of different landforms.

Denevi also compared spectra of Earth and lunar rocks and soils to constrain the maximum amounts of iron- and titanium-bearing minerals that could be on the surface.

Through mapping of the major geologic terrain types, Denevi and her colleagues distinguished three major terrain types on Mercury: smooth plains, intermediate terrain and low-reflectance material (LRM).

“Of the three, smooth plains are a key terrain type,” she said. “The smooth plains cover approximately 40 percent of the surface, and the majority is probably of volcanic origin,” she added. (ANI)

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Galileoscope to make wonders of the night sky more accessible to everyone

March 5, 2009 By Leave a Comment

Berlin, March 5 (ANI): A team of leading astronomers, optical engineers and science educators has designed the Galileoscope – a high quality, easy-to-assemble and easy-to-use telescope, which would make the wonders of the night sky more accessible to everyone.

The Galileoscope was developed as a Cornerstone project of the International Year of Astronomy 2009 (IYA2009).

By encouraging the experience of personally seeing celestial objects, the Galileoscope project aims to facilitate a main goal of IYA2009: promoting widespread access to new knowledge and observing opportunities.

Observing through a telescope for the first time is an experience that shapes our view of the sky and the Universe.

It prompts people to think about the importance of astronomy, and for many, it’s a life-changing experience.

Galileoscopes will open up a whole new world for their users and are an excellent means of pursuing an interest in astronomy during IYA2009 and beyond.

The Galileoscope is named after the Italian astronomer Galileo Galilei, who first observed the heavens through a telescope 400 years ago.

The Galileoscope is optimized to provide views of the very same objects that inspired Galileo all those years ago – including craters and mountains on the Moon, the rings of Saturn, the phases of Venus, a variety of star clusters, and moons orbiting the planet Jupiter.

Galileoscopes are also educational tools, tying in with topics such as mathematics, physics, history and philosophy.

As practical instruments they can be used to demonstrate basic optical theory in a real-world scenario, a technique often praised by educators and pupils themselves.

“Users will learn many aspects of optics and even have a chance to construct two types of telescopes – a modern one and a more primitive one similar to Galileo’s,” said Stephen Pompea, US IYA2009 Project Director and member of the IYA2009 Cornerstone project.

“Building and using a Galileoscope gives kids the feeling that science is fun,” he added.

Galileoscopes are available at a low price of 15 dollars (US) per kit.

Discounts are available for group purchases of 100 or more, bringing the price down even lower, to 12.50 dollars each, reducing costs for schools, colleges, astronomical societies, or even parties of interested individuals.

To further this aim, the Galileoscope Cornerstone project has also initiated the “Give a Galileoscope” program.

Donated Galileoscopes will go to less advantaged schools and other organizations worldwide, especially in developing countries.

This will help bring a modern education to students in poor schools and empower them to pursue science and technology knowledge. (ANI)

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Link established between meteorite impact and massive volcanism 30 mln yrs ago

January 8, 2009 By Leave a Comment

Washington, Jan 8 (ANI): In a new research, scientists have discovered the second example of a meteorite impact that occurred at the same time as massive volcanic activity 30 million years ago in Belarus.

The first time such a coincidence was observed, at the Cretaceous-Tertiary boundary, was the catastrophic event thought to be responsible for the extinction of the dinosaurs, 65 million years ago.

This new event, uncovered after the 17 km diameter Logoisk impact structure in Belarus was precisely dated, is thought to have taken place around 30 million years ago.

The crater was dated using argon isotopes, and found to have occurred at a similar time to a period of massive volcanism known as the Afro-Arabian flood volcanism, which started in NW Yemen at around 30.9 Mya (million years ago), and SW Yemen at around 29.0 Mya.

The impact also coincides broadly with a period of sudden global cooling and sea level fluctuation.

The researchers, led by Sarah Sherlock at the Open University, argue that massive volcanic eruptions and meteorite impacts are likely to have coincided much more frequently than has previously been thought, but because the preservation of impact craters on Earth is poor much of the evidence for these coincidences is lost.

Prior to the study, only one example of an impact coinciding with volcanism had been found: the Chicxulub and Boltysh impacts and the Deccan Traps flood volcanism, all of which occurred at the Cretaceous-Tertiary boundary.

Unlike the Cretaceous-Tertiary event, the combination of the Logoisk impact and the Afro-Arabain flood volcanism does not seem to have caused an extinction event.

The researchers suggest that the reason for this may be that the magnitude of the event was not sufficiently large in comparison.

While the Cretaceous-Tertiary event saw the release of around 8000 billion tons of SO2 by the volcanism and meteorite impact, the Logoisk impact and the Afro-Arabian volcanism are thought to have contributed only 30 billion tons of SO2.

Meteorite impact craters are extremely difficult to date, but an understanding of their age and frequency is crucial to attempts to control the number of future impacts, as well as understanding the links between impacts and other catastrophic events such as large volcanic eruptions and mass extinctions. (ANI)

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Ancient asteroid may have created biggest known landslide on Mars

January 7, 2009 By Leave a Comment

Washington, Jan 7 (ANI): Scientists have said that an asteroid may have triggered a landslide on Mars billions of years ago, which is the size of the entire United States, and the largest known anywhere.

The finding could help solve the origin mystery of Mars’s Arabia Terra region, a vast, midlevel plateau between the planet’s smooth northern lowlands and rugged southern highlands.

According to a report in National Geographic News, estimated at about 1,000 miles (1,600 kilometers) wide, the giant asteroid is believed to have struck Mars’s northern hemisphere billions of years ago.

The cataclysm is thought to have given the planet its topographical split personality — smooth in the north, but bumpy down south.

The impact site became the smooth, low-lying Borealis Basin, about 6,000 miles (10,000 kilometers) across. The southern part of the planet became highlands—in places several miles higher than the basin.

The border of the two regions is sharply defined, except for the Arabia Terra zone. This odd middle ground is neither highlands nor basin.

Until recently, the reason for the region had been unknown.

Arabia Terra is a relic of the giant asteroid impact, according to geophysicist Jeff Andrews-Hanna, of the Colorado School of Mines.

This unusual midland was created when a U.S.-size portion of the highlands broke free and slid 180 miles (300 kilometers) northward, down into the southern rim of the Borealis Basin, Andrews-Hanna said.

In other words, three of Mars’s largest geographic features — the Borealis Basin, the highlands, and Arabia Terra — were formed “virtually instantaneously, in a single catastrophic collision,” the geophysicist said

According to Andrews-Hanna, the first clue that Arabia Terra was formed via landslide is that the relatively flat region has steep slopes at both its northern and southern edges, which is like a giant step.

Similar features occur in other large impact craters, many of which have bull’s-eye patterns—concentric circles or ellipses of steep ridges separated by gently sloping plateaus.

The similarity of Arabia Terra to these other craters indicates that it too might have been created by an impact.

Another clue is that, at Arabia Terra, the inner rim of the Borealis Basin doesn’t line up with its inner rim elsewhere on the planet.

Instead, the rim juts northward by about 300 kilometers, as if a landslide had smudged the clean break seen in areas to the west and east. (ANI)

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Odd-looking Martian craters indicate hidden ice

January 4, 2009 By Leave a Comment

Washington, Jan 4 (ANI): Scientists have defined and analyzed odd-looking Martian craters, which according to them, indicates hidden ice.

Surface features common in the northern and southern mid latitudes of Mars and known as lobate debris aprons and lineated valley fill are believed to have formed either as debris flows mobilized by pore ice or as debris-covered glaciers.

To learn more, Ailish M. Kress and James W. Head, both from the Department of Geological Sciences, Brown University Providence Rhode Island, US, have defined and analyzed ring mold craters, which are abundant on debris aprons and lineated valley fill but not seen in surrounding terrain.

Ring mold craters are concentric crater forms named for their similarity to the cooking implement, in contrast to the bowl-shaped craters that are common at such small sizes.

On the basis of similarities in shape of ring mold, craters to laboratory impact craters in ice and of the physics of impact cratering into pure ice, the authors interpreted that ring mold craters result from projectiles hitting relatively pure ice below a thin debris layer.

These results support the hypothesis that lobate debris aprons and lineated valley fill are debris-covered glaciers and that many hundreds of meters of ice remain in these deposits today on Mars. (ANI)

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