Grönland’daki Petermann Buzulu’ndan Dev Bir Parça Koptu

Kuzey Kutbu’nun 1000 kilometre (km) güneyinde, Grönland’daki kuzeybatı sahilindeki Petermann Buzulu’ndan, 251-253-260 (!) km² (kilometrekare) büyüklüğünde bir buz tabakası koptu. Delaware Üniversitesi’nden (ABD) Andreas Münchow‘a göre bu parçalanma, 1962 yılından bu yana Kuzey Kutbu’ndan kopan en büyük Arktik buzdağı kütlesini oluşturuyor.

arktik
sıfat, coğrafya Fransızca arctique
Kuzey Kutbu’yla ilgili, Kuzey Kutbu yakınında olan.
—TDK

Kopan parçanın kışın yeniden donmaması halinde buzdağının Grönland ve Kanada arasındaki denize kayabileceğini düşünülüyor. Petermann Buzulu’nda çatlakların oluştuğu daha önceden belirlenmişti; yakın zaman içinde buzuldan kopmalar olması bekleniyordu. Münchow, buzdağının güneye inmesi hâlinde bölgedeki deniz trafiğini de etkileyebileceğini söylüyor.

Buzuldaki kopmayı, Kanada Buz Hizmetleri‘nden Trudy Wohlleben’in, NASA’nın uydu görüntülerinden belirlediği söyleniyor. Görüntüler, Petermann Buzulu’nun 70 kilometre (km) uzunluğundaki yüzer buz tabakasının yaklaşık dörtte birini kaybettiğini gösteriyor.

Münchow, kopan buzdağının, ABD’nin 120 günlük gündelik su ihtiyacını karşılayabilecek miktarda içilebilir su içerdiğini belirtiyor. Ayrıca buzuldaki kopmanın küresel ısınmadan kaynaklanıp kaynaklanmadığının henüz netlik kazanmadığını söylüyor. Her yıl Grönland buzullarından binlerce buzdağı kopuyor; ancak bunların boyutu nadiren son kopmadaki düzeylere ulaşıyor. 1979’dan 2009’a kadar Grönland’ın yüzölçümünde meydana gelen erime ve donmaya ait NASA görüntülerini izlemek için http://www.facebook.com/video/video.php?v=146644988697869

Konu ile ilgili daha fazla bilgi için İngilizce kaynaklar..
Ice Island Calves off Petermann Glacier @ NASA
Greenland glacier gives birth to giant iceberg @ ESA
Ice Island calves off Petermann Glacier @ NASA
Petermann Ice Island @ Environment Canada
Petermann Glacier @ Wikipedia
Petermann Ice Island (2010) Spotted in Northwest Greenland @ NOAA


Click to enlarge! Satellite image from Aug. 5, 2010, shows the huge ice island calved from Greenland’s Petermann Glacier. Courtesy of Prof. Andreas Muenchow, University of Delaware.

Greenland glacier calves island 4 times the size of Manhattan, UD scientist reports
A University of Delaware researcher reports that an “ice island” four times the size of Manhattan has calved from Greenland’s Petermann Glacier. The last time the Arctic lost such a large chunk of ice was in 1962.

“In the early morning hours of August 5, 2010, an ice island four times the size of Manhattan was born in northern Greenland,” said Andreas Muenchow, associate professor of physical ocean science and engineering at the University of Delaware’s College of Earth, Ocean, and Environment. Muenchow’s research in Nares Strait, between Greenland and Canada, is supported by the National Science Foundation (NSF).

Satellite imagery of this remote area at 81 degrees N latitude and 61 degrees W longitude, about 620 miles [1,000 km] south of the North Pole, reveals that Petermann Glacier lost about one-quarter of its 43-mile long [70 km] floating ice-shelf.

Trudy Wohlleben of the Canadian Ice Service discovered the ice island within hours after NASA’s MODIS-Aqua satellite took the data on Aug. 5, at 8:40 UTC (4:40 EDT), Muenchow said. These raw data were downloaded, processed, and analyzed at the University of Delaware in near real-time as part of Muenchow’s NSF research.

Petermann Glacier, the parent of the new ice island, is one of the two largest remaining glaciers in Greenland that terminate in floating shelves. The glacier connects the great Greenland ice sheet directly with the ocean.

The new ice island has an area of at least 100 square miles and a thickness up to half the height of the Empire State Building.

“The freshwater stored in this ice island could keep the Delaware or Hudson rivers flowing for more than two years. It could also keep all U.S. public tap water flowing for 120 days,” Muenchow said.

The island will enter Nares Strait, a deep waterway between northern Greenland and Canada where, since 2003, a University of Delaware ocean and ice observing array has been maintained by Muenchow with collaborators in Oregon (Prof. Kelly Falkner), British Columbia (Prof. Humfrey Melling), and England (Prof. Helen Johnson).

“In Nares Strait, the ice island will encounter real islands that are all much smaller in size,” Muenchow said. “The newly born ice-island may become land-fast, block the channel, or it may break into smaller pieces as it is propelled south by the prevailing ocean currents. From there, it will likely follow along the coasts of Baffin Island and Labrador, to reach the Atlantic within the next two years.”

The last time such a massive ice island formed was in 1962 when Ward Hunt Ice Shelf calved a 230 square-mile island, smaller pieces of which became lodged between real islands inside Nares Strait. Petermann Glacier spawned smaller ice islands in 2001 (34 square miles) and 2008 (10 square miles). In 2005, the Ayles Ice Shelf disintegrated and became an ice island (34 square miles) about 60 miles to the west of Petermann Fjord.

Kaynakça
BBCTürkçe, 2010. Grönland’daki bir buzuldan dev bir parça koptu, BBC Türkçe Servisi, Londra, İngiltere, http://www.bbc.co.uk/turkce/haberler/2010/08/100807_greenland_iceberg.shtml, 14 Ağustos 2010 tarihinde ulaşıldı.
UDEL, 2010. Greenland glacier calves island 4 times the size of Manhattan, UD scientist reports, UDaily, University of Delaware, Newark, Delaware, USA, http://www.udel.edu/udaily/2011/aug/greenland080610.html, accessed at August 14th 2010.

Mars’ta Yaşamsal Bir Etkinliğin Varolabileceği İle İlgili Kanıt Mı Bulundu?

Mars jeolojisi ile ilgili araştırmalar devam ediyor. Mars’taki Nili Fossae adlı bölgede killi-karbonatlı minerallerin hidrotermal alterasyon (sıcaksu ile değişim) sonucu oluşumlarını inceleyen ekip, bunun yaşamış olabilecek organizmaların kanıtı olabileceğini düşünüyor. Yapılan araştırma sonucu olarak, Nili Fossae bölgesindeki kayalarda gözlemlenen mineral içeriğinin, Avustralya’nın kuzeybatısındaki Pilbara bölgesinde bulunan ve Dünya’daki yaşamın ilk izlerinin mineral biçimde korunduğu yerdekiyle aynı olduğu belirtiliyor.

Biliminsanları Mars’ta yaşam olduğuna ilişkin fiziksel kanıtları içerdiğini düşündükleri bir bölge bulduklarını açıkladı. Earth And Planetary Science Letters (~Dünya ve Gezengenler ile ilgili Bilimsel Yazılar) dergisinde yayımlanan bulgular, 4 milyar yaşındaki yaşam biçimlerine ilişkin fosillerin gezegenin Nilae Fossae olarak adlandırılan vadi kesiminde gömülü olduğuna işaret ediyor. Ancak araştırmacılar bulguların bir yaşam belirtisi mi yoksa diğer yerbilimsel (jeolojik) hareketlerle oluşan şekiller mi olup olmadığını saptamak için daha kapsamlı incelemeler yapılması gerektiğine dikkat çekiyor. [ http://dx.doi.org/10.1016/j.epsl.2010.06.018 ]

Canlılar gömüldüklerinde karbonlaşıp kömüre dönüşürler. Bölge, 2008 yılında bir araştırma ekibinin, kayalarda karbon mineralleri bulunduğunu saptadığı zaman merak uyandırmıştı. Dolayısıyla, bu Mars’ta hayat olabileceğine ilişkin ilk belirgin işaret.

Şimdi dünya dışındaki canlı arayışları konusunda çalışmalar yürüten Kaliforniya merkezli SETI (İng. Search for Extraterrestrial Intelligence, Tr. Dünyadışından Haberalma Amaçlı Araştırma) adlı bir enstitü Mars’ta saptanan bu kaya parçalarının Avustralya’nın batısında bulunan Pilbara adlı bölgedekilerle benzeştiğini söylüyor. Araştırmanın liderliğini yürüten Adrian Brown, Nilae Fossae’nin içerdiği mineraller dikkate alındığında Pilbara’nın tıpatıp benzeri olduğu görüşünde.

”Pilbara’nın yerkürede yaşama ilişkin en iyi korunan kanıtları içerdiğini” kaydeden Brown, ”Mars’ta yalnızca bir bölgede kömürleşme saptadık. Bu bize, Mars’ta daha önceki dönemlerde yaşamın bulunup bulunmadığını saptamak için daha kapsamlı çalışma yapacağımız bölgenin burası olduğunu gösteriyor.” diye konuştu ve ekledi “Eğer Mars’ta katmanlar, mercanlar veya bir tür mikrobik alanlar oluşturmaya ve bunları burada gömülü tutmaya yetecek yaşam varsa, Dünya’daki fiziğin aynısı burada da olmalıdır.” dedi.

Mars Bilim Laboratuvarı olarak adlandırılan robot, 2018 yılına kadar Mars’a gidecek son araç olacak. Araştırma ekibi Amerikan Uzay ve Havacılık Yönetimi’nin (NASA) bir sonraki insansız Mars seyahatinin Nilae Fossae’yi ziyaret etmesini ve oradaki yaşamın varlığını saptamak için malzeme toplamasını umuyor. Ancak NASA gelecek yıl Mars’a gönderilecek aracı bu antik, kayalık, koşulların belirsiz olduğu vadiye indirmenin çok tehlikeli olduğu görüşünde. Biliminsanları, NASA’nın aracını Mars yüzeyinde nereye indireceğini açıklamasını bekliyor. SETI araştırmacıları ise, NASA’nın aracını bu bölgeye indirmeme kararı almasıyla Mars’ta yaşam olup olmadığına ilişkin esrarı çözmek için önemli bir fırsatın kaçırıldığını savunuyor.

Yayınlanan makaleyi indirmek için tıklayın! (İngilizce, 827 kb ve .pdf)


Click to enlarge! Absorption band maps from CRISM scenes in Nili Fossae showing depth of the 2.3 μm absorption band. (top left) THEMIS+MOLA context map showing location of images, Jezero Crater and Isidis Planitia. (bottom left) FRT CBE5 (left) and FRT BDA8 (right) using 1.3 μm band. (bottom right) 2.3 μm absorption band for carbonate detections overlain on 1.3 μm band image. (top right) HiRISE image PSP_010206_1976 taken at the same time as FRT CBE5

Mars site may hold ‘buried life’
Researchers have identified rocks that they say could contain the fossilised remains of life on early Mars.

The team made their discovery in the ancient rocks of Nili Fossae.

Their work has revealed that this trench on Mars is a “dead ringer” for a region in Australia where some of the earliest evidence of life on Earth has been buried and preserved in mineral form.

They report the findings in the journal Earth and Planetary Science Letters.

The team, led by a scientist from the Search for Extraterrestrial Intelligence Institute (Seti) in California, believes that the same “hydrothermal” processes that preserved these markers of life on Earth could have taken place on Mars at Nili Fossae.

The rocks there are up to four billion years old, which means they have been around for three-quarters of the history of Mars.

When, in 2008, scientists first discovered carbonate in those rocks the Mars science community reacted with great excitement; carbonate had long been sought as definitive evidence that the Red planet was habitable – that life could have existed there.

Carbonate is what life – or at least the mineral portion of a living organism – turns into, in many cases, when it is buried. The white cliffs of Dover, for example, are white because they contain limestone, or calcium carbonate.

The mineral comes from the fossilised remains shells and bones and provides a way to investigate the ancient life that existed on early Earth.

In this new research, scientists have taken the identification of carbonate on Mars a step further.

Adrian Brown from the Seti Institute, who led the research, used an instrument aboard Nasa’s Mars Reconnaissance Orbiter called Crism to study the Nilae Fossae rocks with infrared light.

Then he and his team used exactly the same technique to study rocks in an area in north-west Australia called the Pilbara.

“The Pilbara is very cool,” Dr Brown told BBC News. “It’s part of the Earth that has managed to stay at the surface for around 3.5 billion years – so about three quarters of the history of the Earth.”

“It allows us a little window into what was happening on the Earth at its very early stages.”

And all those billions of years ago, scientists believe that microbes formed some distinctive features in the Pilbara rocks – features called “stromatolites” that can be seen and studied today.

“Life made these features. We can tell that by the fact that only life could make those shapes; no geological process could.”

This latest study has revealed that the rocks at Nili Fossae are very similar to the Pilbara rocks – in terms of the minerals they contain.

And Dr Brown and his colleagues believe that this shows that the remnants of life on early Mars could be buried at this site.

“If there was enough life to make layers, to make corals or some sort of microbial homes, and if it was buried on Mars, the same physics that took place on Earth could have happened there,” he said. That, he suggests, is why the two sites are such a close match.

‘Geological olympics’
Dr Brown and many other scientists had hoped that they would soon have the opportunity to get much closer to these rocks. Nili Fossae was put forward as a potential landing site for Nasa’a ambitious new rover, the Mars Science Laboratory, which will be launched in 2011.

The site was championed by other geologists, including John Mustard from Brown University in Rhode Island, whose team made the case to Nasa to have it included in the landing site shortlist for MSL.

But Nilae Fossae was eventually deemed too dangerous a landing site and it was finally removed from the list in June of this year.

“The rover is being landed remotely – so there’s no human pilot involved; it’s all up to the robot. And [that’s] a very dangerous thing,” said Dr Brown. “You need 20km of smooth terrain and unfortunately at this site it is pretty rocky – those ancient rocks are pretty weathered and the surface is rocky and uneven.”

“It will be visiting another interesting site when it lands, but this is the place that we should be checking out for life on early Mars.”

John Grant, a scientist from the Smithsonian Institution in Washington DC, and a member of the planetary sciences panel that advises Nasa on the MSL mission, spoke to BBC News earlier this year about the choice of landing site.

He said that the objective of mission was a search for “habitability”. It was not, he said, a life detection mission.

“[It] entails looking at geologic environments that may not only have been habitable but where signals associated with that habitability have been preserved,” he told BBC News in February.

But that does not alleviate the disappointment that many feel over having Nili Fossae and all its secrets taken off the table for the mission.

And what makes Mars Science Laboratory even more of a crucial mission for scientists is the fact that it will be the last rover to explore the surface of Mars until 2018 – partly because funding the mission has been so extraordinarily expensive.

Dr Brown described the experience of having his favoured landing site removed from the shortlist as the geological equivalent of having “your city’s Olympic bid rejected”.

MSL will be lowered onto Mars with a landing system called a sky crane
“I also see a race happening here,” he said. “It might take us a couple of decades to build our capability to land [unmanned] rovers somewhere geologically interesting on Mars.

“And in those decades, human space flight capabilities are going to develop and we could have the capability to send humans to Mars.”

So in this race of the human versus the robots, which will win?

“It’s my personal belief,” said Dr Brown, “that by the time real human geologists get to go to Mars, the question of whether there is life on Mars will still be open.”

‘Hydrothermal formation of Clay-Carbonate alteration assemblages in the Nili Fossae region of Mars’ with S. J. Hook, A. M. Baldridge, J. K. Crowley, N. T. Bridges, B. J. Thomson, G. M. Marion, C. R. de Souza Filho and J. L. Bishop (2010) Earth and Planetary Science Letters doi:10.1016/j.epsl.2010.06.018

Kaynakça
BBCTürkçe, 2010. Mars’ta yaşam işareti: Kömür, Bilim ve Teknoloji, BBC Türkçe Servisi, Londra, İngiltere, http://www.bbc.co.uk/turkce/haberler/2010/07/100730_mars_carbonate.shtml, 1 Ağustos 2010 tarihinde ulaşıldı.
Gill, V., 2010. Mars site may hold ‘buried life’, Science and Environment, News, BBC, London, England, http://www.bbc.co.uk/news/science-environment-10790648, accessed at August 1st 2010.
NTVSMNBC, 2010, Mars’ta ‘eski bir yaşam’ olabilir, Uzay, NTV Bilim, NTVMSNBC, İstanbul, Türkiye, http://www.ntvmsnbc.com/id/25119376, 1 Ağustos 2010 tarihinde ulaşıldı