‏إظهار الرسائل ذات التسميات Ancient. إظهار كافة الرسائل
‏إظهار الرسائل ذات التسميات Ancient. إظهار كافة الرسائل

الخميس، 6 سبتمبر 2012

Supernova Explosion Shines Light on Mysteries of an Ancient Galaxy

Supernova Explosion Shines Light on Mysteries of an Ancient Galaxy
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August 30, 2012 Supernova Explosion Shines Light on Mysteries of an Ancient Galaxy

 

           Sn94d

 

An international research team, led by Edo Berger of Harvard University, made the most of a dying star’s fury to probe a distant galaxy some 9.5 billion light-years distant. The dying star, which lit the galactic scene, is the most distant stellar explosion of its kind ever studied. According to Berger, “It’s like someone turned on a flashlight in a dark room and suddenly allowed us to see, for a short time, what this far-off galaxy looks like, what it is composed of.”

The study, published recently in The Astrophysical Journal, describes how the researchers used the exploding star’s light (called an ultra-luminous core-collapse supernova) as a probe to study the gas conditions in the space between the host galaxy’s stars. Berger says the findings reveal that the distant galaxy‘s interstellar conditions appear “reassuringly normal” when compared to those seen in the galaxies of our local universe.

“This shows the enormous potential of using the most luminous supernovae to study the early universe,” he says. “Ultimately it will help us understand how galaxies like our Milky Way came to be.”The discovery of the dying star in this distant galaxy was made using images from the Pan-STARRS1 survey telescope on Haleakala in Maui, Hawai‘i.

“These are the types of exciting and unexpected applications that appear when a new capability comes on line,” said John Tonry, one of the study's co-authors and supernovae researcher at the University of Hawai‘i at Manoa's Institute for Astronomy. “Pan-STARRS is pioneering a new era in deep, wide-field, time-critical astronomy – and this is just the beginning.”

After the Pan-STARRS discovery, spectroscopic follow-up studies using the Multiple Mirror Telescope in Arizona and the 8-meter Gemini North telescope on Mauna Kea, Hawai‘i provided the data used by the team to probe the gas of the distant galaxy’s interstellar environment.

The spectra revealed the signatures of a distant ultra-luminous supernova, and equally important, the unique fingerprints of iron and magnesium within the distant galaxy that hosted the explosion. The galaxy itself contains a very young population of stars (~15 to 45 million years old) with a mass totaling some 2 billon Suns.

The ultra-luminous supernova explosion belongs to a relatively recently-identified and special breed of exploding stars. They are some 10-100 times more luminous than their ordinary less-energetic cousins and unusually blue in color. While the process leading to their demise is still being explored, evidence points to the central core-collapse of a star having as much as 100 times the mass of our Sun. The collapse triggers an enormous explosion that blasts prodigious amounts of heavier elements through the star’s enormous outer layers before expanding into space.

Traditionally, astronomers have used two techniques to study distant galaxies: They would either; 1) look directly for chemical elements leaving bright imprints on the galaxy’s spectrum of light; or 2) search indirectly for dark signatures in the spectrum of an even more distant quasar, which reveals chemical elements in an intervening system that have absorbed light along our line of sight.

Recently, astronomers have supplanted these methods with another: seeking dark absorption imprints in the afterglows of “gamma-ray bursts” (GRBs); these brief flashes are the brightest and most energetic explosions in the universe, but they fade away within hours. The method is also limited by the need for expensive Earth-orbiting satellites to first detect and pinpoint a burst’s location with precision before astronomers can make ground-based studies.

“The beauty of studying distant galaxies using ultra-luminous supernovae as a tool is that it eliminates the need for satellites and offers more time for study,” says Alicia Soderberg of Harvard University. “A typical ultra-luminous supernova can take several weeks to fade away.”

The study by Berger and his team provides the ?rst direct demonstration that ultra-luminous supernovae can serve as probes of distant galaxies. Their results suggest that with the future combination of large survey and spectroscopic telescopes ultra-luminous supernovae could be used to probe galaxies 90 percent of the way back to the Big Bang.*

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It never ceases to amaze me that everytime we witness a supernova billions of lightyears away, that it is entirely possible that we are witnessing the destruction of the star that created the atoms we see (and are composed of) today.

Posted by:Mulvey |August 31, 2012 at 06:27 AM


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الاثنين، 27 أغسطس 2012

Most Ancient Stars in Universe Hidden in Dwarf Galaxies

Most Ancient Stars in Universe Hidden in Dwarf Galaxies
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August 22, 2012 Most Ancient Stars in Universe Hidden in Dwarf Galaxies

 

                                    
                             Dwarf-galaxy-black-hole_1

 

Observations using ESO’s Very Large Telescope have been used to solve an important astrophysical puzzle concerning the oldest stars in our galactic neighborhood hidden until recently in dwarf galaxies orbiting the Milky Way. In comparison to the Milky Way, a massivespiral galaxy, most dwarf galaxies are blob-like, 85% smaller (around 6700 vs 100,000 light-years across), containing around 30 billion stars.

When the Universe was just a fraction of its current age, and galaxies such as the one we inhabit were nowhere to be seen, stars formed inside odd structures, that have long since disappeared.  These structures are called dwarf irregulars, and the scientist believes that the peculiar type of stellar formation processes they display may resemble the original one and may provide clues as to how stars appeared shortly after the Big Bang. 

Unlike massive galaxies, such as the Milky Way, with highly-defined central regions, spiral arms and so on, dwarf irregulars are very small and diffuse groups of stars, which are the last thing to spring to mind when thinking of the word “galaxy”. Star formation in dwarfs today is similar to star formation right after the Big Bang.

“Our improved approach allows us to uncover the primitive stars hidden among all the other, more common stars” said Else Starkenburg, lead author of the paper reporting the seminal 2010 stuty.

Primitive stars are thought to have formed from material forged shortly after the Big Bang, 13.7 billion years ago. They typically have less than one thousandth the amount of chemical elements heavier than hydrogen and helium found in the Sun and are called “extremely metal-poor stars." They belong to one of the first generations of stars in the nearby Universe. Such stars are extremely rare and mainly observed in the Milky Way.

Cosmologists think that larger galaxies like the Milky Way formed from the merger of smaller galaxies. Our Milky Way’s population of extremely metal-poor or “primitive” stars should already have been present in the dwarf galaxies from which it formed, and similar populations should be present in other dwarf galaxies. Metals” are all the elements other than hydrogen and helium. Such metals, except for a very few minor light chemical elements, have all been created by the various generations of stars.

“So far, evidence for them has been scarce,” says co-author Giuseppina Battaglia. “Large surveys conducted in the last few years kept showing that the most ancient populations of stars in the Milky Way and dwarf galaxies did not match, which was not at all expected from cosmological models.”

Element abundances are measured from spectra, which provide the chemical fingerprints of stars . Since the dwarf galaxies are typically 300 000 light years away — which is about three times the size of our Milky Way — only strong features in the spectrum could be measured, like a vague, smeared fingerprint. The team found that none of their large collection of spectral fingerprints actually seemed to belong to the class of stars they were after, the rare, extremely metal-poor stars found in the Milky Way.

The team of astronomers around Starkenburg has now shed new light on the problem through careful comparison of spectra to computer-based models. They found that only subtle differences distinguish the chemical fingerprint of a normal metal-poor star from that of an extremely metal-poor star, explaining why previous methods did not succeed in making the identification.

The astronomers also confirmed the almost pristine status of several extremely metal-poor stars thanks to much more detailed spectra obtained with the UVES instrument on ESO’s Very Large Telescope. “Compared to the vague fingerprints we had before, this would be as if we looked at the fingerprint through a microscope,” explains team member Vanessa Hill. “Unfortunately, just a small number of stars can be observed this way because it is very time consuming.”

“Among the new extremely metal-poor stars discovered in these dwarf galaxies, three have a relative amount of heavy chemical elements between only 1/3000 and 1/10 000 of what is observed in our Sun, including the current record holder of the most primitive star found outside the Milky Way,” says team member Martin Tafelmeyer.

“Not only has our work revealed some of the very interesting, first stars in these galaxies, but it also provides a new, powerful technique to uncover more such stars,” concludes Starkenburg. “From now on there is no place left to hide!”

The image at the top of the page shows star-forming dwarf galaxy Henize 2-10 in optical light (red, green and blue), radio waves (yellow), and x-rays (purple). The suspected location of its massive black hole is marked with a cross.

The Daily Galaxy via 

Image Credit: X-ray (NASA/CXC/Virginia/A.Reines et al.), radio (NRAO/AUI/NSF/Virginia/A.Reines et al.), optical (NASA/STScI/Virginia/A.Reines et al.)

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'Curiosity's' Trek Up Mars' Aeolis Mons: The Search for Ancient Life

'Curiosity's' Trek Up Mars' Aeolis Mons: The Search for Ancient Life
'Curiosity's' Trek Up Mars' Aeolis Mons: The Search for Ancient LifeThe Daily Galaxy --Great Discoveries Channel: Sci, Space, TechFollow the Daily GalaxyAdd Daily Galaxy to igoogle page AddThis Feed Button Join The Daily Galaxy Group on Facebook Follow The Daily Galaxy Group on twitter  « The Complete 'Mars Science Lab' Descent in HD Video |Main| Enigma? Black Holes Glow with a Bright Ring of Light (Today's Most Popular) »

August 17, 2012 'Curiosity's' Trek Up Mars' Aeolis Mons: The Search for Ancient Life

 

           Mars-mount-sharp

 

The Mars Curiosity science mission goal is to look for chemical evidence of ancient life preserved within exposures near the base of a five-kilometers high mound of layered materials at the center of Gale crater. The first images in from the rover’s navigation cameras suggested one possibility for signs of microbial life when they revealed whitish linear features in a shallow trench scoured out by the blast of the landing system’s retrorockets. The lines, says John Grotziner, project manager of NASA's Mars Science Laboratory mission, could be fractures filled with water-altered minerals — key targets for exploration in the mission’s goal of assessing whether ancient Mars could have supported life.

Only several hundred meters away is a a five-meter-high slope, or scarp, that separates the dusty desert pavement on which the rover landed from the more hummocky terrain that lies beyond, a second option in the search for ancient signs of life. The scarp marks the edge of materials deposited at the foot of an alluvial fan, a sedimentary feature left behind from floods that once spilled down from the rim of Gale Crater and might reveal evidence of an ancient lake.

But the Curiosity’s ultimate destination is the 5.5-kilometre-high Aeolis Mons, dubbed Mount Sharp (image above) by the science team. Data from orbiting spacecraft suggest that deposits on the mountain’s lower shoulders were formed in water, which represent the science team’s optimal chance of working out whether microbes could have lived on Mars billions of years ago.

"This may be one of the thickest exposed sections of layered sedimentary rocks in the solar system," said Joy Crisp, MSL Deputy Project Scientist from NASA's Jet Propulsion Laboratory. "The rock record preserved in those layers holds stories that are billions of years old -- stories about whether, when, and for how long Mars might have been habitable."

The red planet, says Robert Zubrin, founder of The Mars Society, is essentially a Rosetta stone for determining the prevalence and diversity of life in the universe.

"If life will develop wherever it has a decent planet, it means that the universe is filled with life," Zubrin says, "And if life is everywhere, it means intelligence is everywhere. It means we're living in an inhabited universe. This is something that thinking men and women have wondered about for thousands of years." There's a good chance Curosity and the MarsScience Lab will finally answer.

 

           1-s2.0-S0019103511001643-gr3

The Daily Galaxy via http://www.nature.com/news/mars-scientists-await-feast-of-data-1.11169

Image credit: http://marsjournal.org/contents/2010/0004/

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Earth Is The True Planet Of War, Not Mars (Curiosity Rover)
http://www.youtube.com/watch?v=sj5ju9ag2ZI

Posted by:Deep Space |August 16, 2012 at 09:49 AM

NASA has been covering up evidence of life on Mars past or present. This is the most ridiculous amateur attempt to mislead again with this stupid waste of time and money. It is a joke at this point.
What are they afraid of anyway? Stop this nonsense - come out with the truth -

Posted by:Babi |August 17, 2012 at 09:14 AM

The question is, Babi, just what are YOU afraid of?!

Posted by:Ruth Mc |August 19, 2012 at 09:48 AM


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الأحد، 26 أغسطس 2012

Phobos -- "Mars' Mystery Moon May Harbor Proof of Ancient Life"

Phobos -- "Mars' Mystery Moon May Harbor Proof of Ancient Life"
Phobos -- "Mars' Mystery Moon May Harbor Proof of Ancient Life"The Daily Galaxy --Great Discoveries Channel: Sci, Space, TechFollow the Daily GalaxyAdd Daily Galaxy to igoogle page AddThis Feed Button Join The Daily Galaxy Group on Facebook Follow The Daily Galaxy Group on twitter  « Mars Rover Curiosity Flexes Its Robotic Arm Today |Main| Monster Black Holes of the Early Universe --"Did They Form Inside Galaxies or Create Them?" »

August 21, 2012 Phobos -- "Mars' Mystery Moon May Harbor Proof of Ancient Life"

 

           1-fantasticpho

 

Some 135 years after its discovery, Mars’ largest moon Phobos is seen in fantastic detail – and in 3D – in an image taken by ESA’s Mars Express spacecraft as it passed just 100 km by. This view is much different to the faint object that astronomer Asaph Hall would have just been able to make out as he observed the Red Planet through the United States Naval Observatory’s 66 cm telescope in 1877. Through this telescope he discovered Mars’ smaller, outermost moon Deimos on 12 August and the larger, innermost moon Phobos on 18 August.

More than a century later later, spacecraft in orbit around Mars are studying Phobos in unprecedented detail. In this image, a bite-sized chunk appears to be missing from the right edge of the irregular shaped moon – this is a side-on view of the rim of large impact crater Stickney, so-called after the maiden name of the discoverer’s wife. Families of grooves appear to emanate from Stickney, carving channels across the approximately 27 km length of the moon.

Initially thought to be associated with the Stickney impact crater, one recent theory suggests that they were instead formed when Phobos passed through debris clouds thrown up from the surface of Mars by asteroid impacts onto the planet’s surface. Orbiting Mars at just 6000 km from the planet’s surface, it is closer to its parent planet than any other known moon in our Solar System.

The moon’s proximity means that it hurtles around Mars faster than the planet rotates: for an observer on the surface of Mars, Phobos would appear to rise and set twice a day. The moon’s orbit is decreasing and in some 50 million years time it will likely break up to form a debris ring around Mars, before colliding with the planet’s surface.

Earlier this year, experts at Purdue University have suggested that a  mission to Phobos could return with alien life.“A sample from Phobos, which is much easier to reach than the Red Planet itself, would almost surely contain Martian material blasted off from large asteroid impacts,” said Jay Melosh, a distinguished professor of earth, atmospheric and planetary sciences and physics and aerospace engineering at Purdue.

“If life on Mars exists or existed within the last 10 million years, a mission to Phobos could yield our first evidence of life beyond Earth.”

Melosh led a team chosen by NASA’s Planetary Protection Office to evaluate if a sample from Phobos could contain enough recent material from Mars to include viable Martian organisms. The study was commissioned to prepare for the failed 2011 Russian Phobos-Grunt mission, but there is continued international interest in a Phobos mission, he said. It will likely be a recurring topic as NASA reformulates its Mars Exploration Program.

A Phobos mission was discussed at NASA’s Concepts and Approaches for Mars Exploration workshop and a report issued Tuesday stated that the Martian moons are “important destinations that may provide much of the value of human surface exploration at reduced cost and risk.”

Melosh collaborated with Kathleen Howell, the Hsu Lo Professor of Aeronautical and Astronautical Engineering, and graduate students Loic Chappaz and Mar Vaquero on the project.

The researchers combined their expertise in impact cratering and orbital mechanics to determine how much material was displaced by particular asteroid impacts and whether individual particles would land on Phobos, the closer of the two Martian moons.

The team concluded that a 200-gram sample scooped from the surface of Phobos could contain, on average, about one-tenth of a milligram of Mars surface material launched in the past 10 million years and 50 billion individual particles from Mars. The same sample could contain as much as 50 milligrams of Mars surface material from the past 3.5 billion years.

“The time frames are important because it is thought that after 10 million years of exposure to the high levels of radiation on Phobos, any biologically active material would be destroyed,” Howell said. “Of course older Martian material would still be rich with information, but there would be much less concern about bringing a viable organism back to Earth and necessary quarantine measures.”

When an asteroid hits the surface of a planet it ejects a cone-shaped spray of surface material, similar to the splash created when someone does a cannonball into a swimming pool. These massive impacts pulverize the surface material and scatter high-speed fragments. The team calculated that the bulk of the fragments from such a blast on Mars would be particles about one-thousandth of a millimeter in diameter, or 100 times smaller than a grain of sand, but similar in size to terrestrial bacteria.

The team followed the possible paths the tiny particles could take as they were hurtled from the planet’s surface through space, examining possible speeds, angles of departure and orbital forces. The team plotted more than 10 million trajectories and evaluated which would intercept Phobos and where they might land on the moon during its eight-hour orbit around Mars.

The probability of a particle landing on Phobos depends primarily on the power of the blast that launched it from the surface, Chappaz said.

“It is estimated that during the past 10 million years there have been at least four large impact events powerful enough to launch material into space, and we focused on several large craters as possible points of origin,” he said. “It turns out that no matter where Phobos is in its orbit, it would have captured material from these powerful impact events.”

After the team submitted its report, scientists identified a large, nearly 60-kilometers-in-diameter crater on Mars. The crater, named Mojave, is estimated to be less than 5 million years old, and its existence suggests that there would be an even greater amount of Martian material on Phobos that could contain viable organisms than estimated, Melosh said.

“It is not outside the realm of possibility that a sample could contain a dormant organism that might wake up when exposed to more favorable conditions on Earth,” he said. “I participated in a study that found that living microbes can survive launch from impacts on rock, and other studies have shown some microscopic organisms can tolerate a lot of cosmic radiation.”

This possibility has been a consideration for some time, and Michael Crichton’s “The Andromeda Strain” brought it to public consciousness in 1969. However the movie scenario of a fatal contamination is unlikely, Melosh said.

“Approximately one ton of Martian material lands on Earth every year, ” he said. “There is a lot more swapping back and forth of material within our solar system than people realize. In fact, we may owe our existence to life on Mars.”

“It’s difficult to believe there hasn’t been life somewhere out there in the vast expanse of space,” Howell said. “The question is if the timeline overlaps with ours enough for us to recognize it. Even if we found no evidence of life in a sample from Phobos, it would not be a definitive answer to the question of whether or not there was life on Mars. There still may have been life that existed too long ago for us to detect it.”

The image below shows the orbits of the Martian moons Phobos and Deimos and the spread of potential particle trajectories from an asteroid impact on Mars.

 

          Mars-moons

 

The Daily Galaxy via purdue.edu/newsroom

 

The Daily Galaxy via European Space Agency

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الثلاثاء، 7 أغسطس 2012

Ancient Mars: "The Water Planet"? --'Curiosity' Mission May Provide Proof (Weekend Feature)

Ancient Mars: "The Water Planet"? --'Curiosity' Mission May Provide Proof (Weekend Feature)
Ancient Mars: "The Water Planet"? --'Curiosity' Mission May Provide Proof (Weekend Feature)The Daily Galaxy --Great Discoveries Channel: Sci, Space, TechFollow the Daily GalaxyAdd Daily Galaxy to igoogle page AddThis Feed Button Join The Daily Galaxy Group on Facebook Follow The Daily Galaxy Group on twitter  « Image of the Day --NASA's Gale Crater Mars Landing Site for Tomorrow's 'Search-for-Life' Mission |Main| View Now! NASA Live Streams Mars 'Curiosity' Landing »

August 05, 2012 Ancient Mars: "The Water Planet"? --'Curiosity' Mission May Provide Proof (Weekend Feature)

 

           6a00d8341bf7f753ef0176156db59a970c-500wi

 

"We can now say that the planet was altered on a global scale by liquid water about four billion years ago." John Carter of the University of Paris.

Will the newly defined search zone for The Mars Curiosity rover following its Aug. 5th touchdown prove Carter right? The Curiosity Science Mission goal is to look for chemical evidence of ancient life preserved within exposures near the base of a five-kilometers high mound of layered materials at the center of Gale crater.

Because of its history, 96-mile wide Gale Crater crater with its strangely sculpted mountain --three times higher than the Grand Canyon is deep--is the ideal place for Curiosity to conduct its mission of exploration into the Red Planet's past. Researchers plan to use Curiosity to study layers in the mountain that hold evidence about wet environments of early Mars.

An instrument on Curiosity can check for any water that might be bound into shallow underground minerals along the rover's path. Today the Red Planet is a radiation-drenched, bitterly cold, bleak world. Enormous dust storms explode across the barren landscape and darken Martian skies for months at a time. But data from the Mars Reconnaissance Orbiter suggest that Mars once hosted vast lakes and flowing rivers.

Minerals in northern Mars craters observed by two NASA orbiters suggested that a phase in Mars' early history with conditions favorable to life occurred globally, not just in the south. Southern and northern Mars differ in many ways, so the extent to which they shared ancient environments has been open to question.

In recent years, the European Space Agency's Mars Express orbiter and NASA's Mars Reconnaissance Orbiter have found clay minerals that are signatures of a wet environment at thousands of sites in the southern highlands of Mars, where rocks on or near the surface are about four billion years old. Until this week, no sites with those minerals had been reported in the northern lowlands, where younger volcanic activity has buried the older surface more deeply.

French and American researchers report that some large craters penetrating younger, overlying rocks in the northern lowlands expose similar mineral clues to ancient wet conditions. Other types of evidence about liquid water in later epochs on Mars tend to point to shorter durations of wet conditions or water that was more acidic or salty.

The researchers used the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), an instrument on the Mars Reconnaissance Orbiter, to check 91 craters in the northern lowlands. In at least nine, they found clays and clay-like minerals called phyllosilicates, or other hydrated silicates that form in wet environments on the surface or underground.

Earlier observations with the OMEGA spectrometer on Mars Express had tentatively detected phyllosilicates in a few craters of the northern plains, but the deposits are small, and CRISM can make focused observations on smaller areas than OMEGA.

"We needed the better spatial resolution to confirm the identifications," Carter said. "The two instruments have different strengths, so there is a great advantage to using both."* CRISM Principal Investigator Scott Murchie of Johns Hopkins University Applied Physics Laboratory, said that the findings aid interpretation of when the wet environments on ancient Mars existed relative to some other important steps in the planet's early history.

The prevailing theory for how the northern part of the planet came to have a much lower elevation than the southern highlands is that a giant object slammed obliquely into northern Mars, turning nearly half of the planet's surface into the solar system's largest impact crater. The new findings suggest that the formation of water-related minerals, and thus at least part of the wet period that may have been most favorable to life, occurred between that early giant impact and the later time when younger sediments formed an overlying mantle.

"That large impact would have eliminated any evidence for the surface environment in the north that preceded the impact," Murchie said. "It must have happened well before the end of the wet period."

The three-dimensional image at the top of the page shows a trough in the Nili Fossae region of Mars shows a type of minerals called phyllosilicates (in magenta and blue hues) concentrated on the slopes of mesas and along canyon walls. The abundance of phyllosilicates shows that water played a sizable role in changing the minerals of a variety of terrains in the planet's early history.

"Layering at the top of the large mound at the center of Gale crater [landing site] is similar to layering visible in western Medusae Fossae Formation exposures, so Curiosity may be able to examine these materials up close, providing the first direct evidence of how they were formed," said Jim Zimbelman, geologist at the National Air and Space Museum’s Center for Earth and Planetary Studies. "This is exciting because so far none of our orbiting spacecraft have been able to measure the composition of MFF materials, something crucial to any explanation of its origin."

The Daily Galaxy via NASA/JPL

 

Posted at 09:00 AM | Permalink



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John Carter? John Carter of Mars?

;-)

Barsoom!

Posted by:Steve Olson |August 05, 2012 at 01:13 PM


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الخميس، 2 أغسطس 2012

Are Polygons of Mars Proof of Ancient Oceans?

Are Polygons of Mars Proof of Ancient Oceans?
Are Polygons of Mars Proof of Ancient Oceans? The Daily Galaxy --Great Discoveries Channel: Sci, Space, TechFollow the Daily Galaxy     « Image of the Day: 'Fomalhaut' --A Spectacular Alien Star System |Main

July 28, 2012 Are Polygons of Mars Proof of Ancient Oceans?

 


          


 


In 2008, NASA scientists working with images from the Mars Phoenix mission were baffled by an unexpected difference between what they thought they would see and what Phoenix is showed them. Among the spectacular images Phoenix relayed was a color mosaic of the terrain looking out from the lander showing "polygons" of the northern plains.

Debate over the origin of large-scale polygons ( a flat shape consisting of straight lines that are joined to form a closed chain or circuit hundreds of meters to kilometers in diameter) on Mars remains active even after several decades of detailed observations. Similarity in geometric patterns on Mars and Earth has long captured the imagination. In this new article from GSA Today, geologists at The University of Texas at Austin examine these large-scale polygons and compare them to similar features on Earth's seafloor, which they believe may have formed via similar processes.

Through examination of THEMIS, MOLA, Viking, and Mariner data and images, planetary scientists have found that areas on the northern plains of Mars are divided into large polygon-shaped portions and that sets of these polygons span extensive areas of the Martian surface. Smaller polygon-shaped bodies are found elsewhere on Mars, but these are best explained by thermal contraction processes similar to those in terrestrial permafrost environments and not likely to form larger polygons.


 


                


Lorena Moscardelli and her colleagues from The University of Texas at Austin have presented a detailed comparison of the geometric features of these large Martian polygons and similar features found in deep-sea sediments here on Earth. Moscardelli and colleagues note striking similarities.


On Earth, polygon-shaped areas, with the edges formed by faults, are common in fine-grained deep-sea sediments. Some of the best examples of these polygon-fault areas are found in the North Sea and the Norwegian Sea. These are imaged using detailed, 3-D seismic surveys conducted to search for offshore oil and gas deposits. Images reproduced in this paper show that these deep-water polygons are also 1,000 meters or greater in diameter.


While the details of deep-sea polygon formation on Earth are complex, Moscardelli and her colleagues conclude that the majority of these polygons form in a common environment: sediments made up of fine-grained clays in ocean basins that are deeper than 500 meters, and when these sediments are only shallowly buried by younger sediments. A key observation -- also made recently by Michelle Cooke at the University of Massachusetts -- is that the physical mechanism of polygon formation requires a thick, wet, and mechanically weak layer of sediment.


Moscardelli and colleagues also conclude that the slope angle of the sea floor plays an important role in both the formation and preservation of these polygons. Where the seafloor slope is very gentle (slopes less than half a degree), the polygons have very regular shapes and sizes. In many locations where polygons have formed on top of buried topographic features on the seafloor, the shapes of the polygons were altered, and in some cases were broken up and disrupted where the slopes were steepest. Both observations are consistent with deformation of the soft marine sediments as they creep or flow downslope in these areas.


In the northern plains of Mars, where the surface is basically flat, the polygons have very regular shapes and sizes -- remarkably similar to the deep-sea polygons found on Earth. In places where the topography on Mars is more varied, and where there may be evidence for other sediment-transport features on the surface, areas of deformed and disrupted polygons can be found -- again similar to the disrupted polygons here on Earth.


On the basis of these striking similarities, the University of Texas team concludes that these features most likely share a common origin and were formed by similar mechanisms in a similar environment. The team argues that the Martian polygons were formed within a thick, wet, and weak layer of fine-grained sediments that were deposited in a deep-water setting, similar to the Earth polygons. Thus, these interesting geometric features may provide additional evidence for the existence of an ocean in the northern portion of Mars approximately three billion years ago.


The topographic map above from Mars Global Surveyor shows colour-coded altitudes; the blue areas are the lowest and correspond to the possible ancient ocean in the northern hemisphere.The color-coded elevation map below of the local terrain on the north side of NASA's Phoenix Mars Lander shows the contours of polygons and relationship of polygon boundaries to trenches and other features in the workspace of the lander's Robotic Arm.


 


          


The Daily Gallaxy via geosociety,org


Image credits: NASA/JPL

Posted at 11:00 AM | Permalink



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Sounds like a pretty good plan to me dude.


www.Anon-Get.tk

Posted by:RingDooo |July 28, 2012 at 01:00 PM


Might be frost working in wet ground also:


http://visitnewfoundland.ca/geology.html

Posted by:Ken |July 28, 2012 at 03:49 PM


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