اكتشاف أول دوامة حارة في النظام الشمسي

[Eng.Junior]

هونولولو، هاواي (CNN) -- نجح علماء الفضاء في اكتشاف منطقة حارة في القطب الجنوبي من كوكب زحل، وهي أول "دوامة حارة" يتم اكتشافها في النظام الشمسي.



واستعمل العلماء منظارا ضخما لرؤية هذه الدوامة، وتمكنت الأجهزة التي تعمل بالأشعة فوق الحمراء من التقاط سلسلة من الصور ستساعد في الإجابة عن الكثير من الأسئلة التي قد تكون على علاقة ببعض الظواهر المناخية، بحسب وكالة الأسوشيتد برس.



ويقول فريق العلماء إنه لم يسبق ان التقطت، من الأرض، صورا بهذه الدقة والوضوح لكوكب زحل، من قبل.



وستنشر مجلة "جورنال ساينس" تقريرا عما قام به العلماء في عددها المقبل.



ويعتقد العلماء أن هذه المنطقة القطبية في زحل، تحتوي على أعلى درجات الحرارة الموجودة على هذا الكوكب، إلا أنهم لم يفصحوا عن درجة الحرارة.



وتوجد الدوامات القطبية على كوكب الأرض، والمشتري، والمريخ، والزهرة، وهي عادة أكثر برودة من محيطها.



إلا أن الصور الملتقطة لكوكب زحل تقدم أول دليل لوجود دوامة قطبية بدرجات حرارة أكثر دفئا.



فعلى الأرض مثلا، توجد "دوامة القطب الشمالي" في شمال شرق الولايات المتحدة وكندا، وهي ترسل الهواء البارد إلى السهول الشمالية في الولايات المتحدة.



ويحار العلماء الآن في تفسير ظاهرة وجود منطقة حارة على مسافة بضع درجات من القطب، وهم ينتظرون صورا ومعلومات من المركبة كاسيني، التي تدور حاليا حول كوكب زحل.

[amoni]

When the temperature soars, coral reefs might cool off by creating their own clouds.

Research from the Great Barrier Reef off the Australian coast shows that corals are packed full of the chemical dimethyl sulphide, or DMS. When released into the atmosphere, DMS helps clouds to form, which could have a large impact on the local climate.

In the air, DMS is transformed into an aerosol of tiny particles on which water vapour can condense to form clouds. This sulphur compound is also produced in large amounts by marine algae and gives the ocean its distinctive smell. Algae play a vital part in regulating Earth's climate, but no one had looked at whether coral reefs might have a similar role.

Graham Jones of the Southern Cross University in Lismore, Australia, and colleagues measured DMS concentrations in corals in the Great Barrier Reef and its surrounding water. They found that the mucus exuded by the coral contained the highest concentrations of DMS so far recorded from any organism. A layer rich in DMS formed at the sea surface above the reef, where it was picked up by the wind.

"Although globally the emission of DMS from the Great Barrier Reef is not huge, on a regional basis it is very significant," says Jones.
Missing link

The big question now is what effect this will have on the climate. "The coral is a concentrated source of DMS, which could affect the formation of clouds in that region," says Peter Liss, an environmental chemist and DMS expert at the University of East Anglia, Norwich, UK.

The Australian team plans to study the impact of the reef and other corals on local climate over the next few years. "We don't know how the DMS emitted by the coral relates to cloudiness and the radiative climate over the reef," says Jones. "That's the missing link."

But their findings help to solve a 30-year puzzle. Surveys in the 1970s found very high concentrations of aerosol particles in the air above the Great Barrier Reef. The coral was thought to be the source, but the mechanism by which the reef might have caused the aerosol count to soar was not known. "They didn't know about DMS in the 1970s," says Jones.
Gaia-like feedback

The research also raises another intriguing possibility: that coral can use a Gaia-like feedback mechanism to regulate the amount of sunlight they are exposed to. The "Gaia theory" is that life on Earth regulates its environment to keep itself healthy.

In lab experiments, Jones and his team showed that corals produce more DMS when the symbiotic algae inside their tissues become stressed by high temperatures or UV radiation. If this DMS seeds more clouds, the coral could have evolved a way to reduce the water temperature or UV exposure. "We've got a long way to go to conclusively demonstrate this, but we've got a lot of ammunition," says Jones.

For 20 years, scientists have been hunting for evidence that free-floating marine algae can operate a DMS-dependent feedback mechanism to dampen global warming's effects. Because reefs are a static source of DMS, it might be easier to show an effect, says Jones. "Coral reefs would be a great place to show Gaia in action," he says. "This is the first time that processes going on in coral reefs are being connected to climatic processes."

[amoni]

NASA's chief has warned space enthusiasts that the agency will become a financial target to outsiders when the US President sends his proposed budget to Congress on 7 February.

NASA is expected to see an increase in its budget to fund a programme of human exploration of the Moon and Mars. But most other non-defence government agencies and departments should see cuts. So the outgoing NASA administrator, Sean O'Keefe, anticipates fights on all fronts for the space agency's proposed funds.

"I expect this year to be just as hard, if not harder," agreed US congressman Dave Weldon, who sits on the subcommittee overseeing NASA funding. Both men were speaking at the 1st Space Exploration conference in Orlando, Florida, US, on Monday.

NASA's anticipated budget increase is largely due to the plans to return to the Moon. President George W Bush outlined the Vision for Space Exploration programme in 2004. It aims to fly humans back to the Moon by 2020 and prepare them for future journeys to Mars.

The programme outlined the future increases to NASA's budget needed to accomplish this feat. NASA requested and received $16.2 billion for Fiscal Year 2005 (1 October 2004 to 30 September 2005), a 5.6% increase on the previous year. The exploration plan anticipates a budget of $17.0 billion for FY2006 - a 4.7% increase.

Of that total, the Moon-Mars programme - named Project Constellation - is anticipated to receive $6.6 billion over five years, beginning in FY2005.
Key challenge

O'Keefe will leave NASA soon after the proposed budget is released, though President Bush is yet to nominate his replacement. A key challenge for any incoming administrator will be to maintain funding for the space program over the long term, says Weldon.

"In the next two or three decades, we will be trying to pull this off in a very, very difficult climate," says Weldon, who represents a district encompassing Cape Canaveral Air Force Station. He says that in 2008, for example, the "baby-boomer bow wave of social security demand is going to begin".

Also at the conference on Monday, Lockheed Martin announced its team of partner companies to compete for the contract to build the Crew Exploration Vehicle - the successor to the space shuttle.

The group will include United Space Alliance, Honeywell, Orbital Sciences, Hamilton Sunstrand and EADS Space Transportation. Boeing and Northrop Grumman have already agreed to work together on a separate CEV proposal.