Tuesday, August 19, 2008
Sloshing Inside Earth Changes Protective Magnetic Field
 | By Jeremy Hsu Staff Writer posted: 18 August 2008 06:35 am ET |
Something beneath the surface is changing Earth's protective magnetic field, which may leave satellites and other space assets vulnerable to high-energy radiation.
The gradual weakening of the overall magnetic field can take hundreds and even thousands of years. But smaller, more rapid fluctuations within months may leave satellites unprotected and catch scientists off guard, new research finds.
A new model uses satellite data from the past nine years to show how sudden fluid motions within the Earth's core can alter the magnetic envelope around our planet. This represents the first time that researchers have been able to detect such rapid magnetic field changes taking place over just a few months.
"There are these changes in the South Atlantic, an area where the magnetic field has the smallest envelope at one third [of what is] normal," said Mioara Mandea, a geophysicist at the GFZ German Research Center for Geosciences in Potsdam, Germany.
Even before the newly detected changes, the South Atlantic Anomaly represented a weak spot in the magnetic field — a dent in Earth's protective bubble.
Bubble bobble
The Earth's magnetic field extends about 36,000 miles (58,000 km) into space, generated from the spinning effect of the electrically-conductive core that acts something like a giant electromagnet. The field creates a tear-drop shaped bubble that has constantly shielded life on Earth against much of the high-energy radiation flowing from the sun.
The last major change in the field took place some 780,000 years ago during a magnetic reversal, although such reversals seem to occur more often on average. A flip in the north and south poles typically involves a weakening in the magnetic field, followed by a period of rapid recovery and reorganization of opposite polarity.
Some studies in recent years have suggested the next reversal might be imminent, but the jury is out on that question.
Measuring interactions between the magnetic field and the molten iron core 1,864 miles (3,000 km) down has proven difficult in the past, but the constant observations of satellites such as CHAMP and Orsted have begun to bring the picture into focus.
Electric storm
Mandea worked with Nils Olsen, a geophysicist at the University of Copenhagen in Denmark, to create a model of the fluid core that fits with the magnetic field changes detected by the satellites.
However, the rapid weakening of the magnetic field in the South Atlantic Anomaly region could signal future troubles for such satellites. Radiation storms from the sun could fry electronic equipment on satellites that suddenly lacked the protective cover of a rapidly changing magnetic field.
"For satellites, this could be a problem," Mandea told SPACE.com. "If there are magnetic storms and high-energy particles coming from the sun, the satellites could be affected and their connections could be lost."
The constant radiation bombardment from the sun blows with the solar wind to Earth, where it flows against and around the magnetic field. The effect creates the tear-drop shaped magnetosphere bubble, but even the powerful field cannot keep out all the high-energy particles.
Topsy-turvy history
A large sunspot set off a major radiation storm in 2006 that temporarily blinded some sun-watching satellites. Astronauts on the International Space Station retreated to a protected area as a precaution to avoid unnecessary radiation exposure.
The Earth's overall magnetic field has weakened at least 10 percent over the past 150 years, which could also point to an upcoming field reversal.
Mandea and Olsen hope to continue refining their model with updated observations, and perhaps to eventually help predict future changes in the Earth's magnetic field.
Monday, August 18, 2008
The Great Firewall of China
August 18th, 2008 by AdamLynn
The Beijing Olympics are underway with the spotlight on China. Unfortunately, our TV announcers are so awed by the grandeur of the spectacle that they are overlooking the country’s authoritarian regime and its stranglehold on free speech.
China now has the world’s largest number of Internet users, having recently surpassed the United States. This number, however, doesn’t account for whether the Chinese government allows for a free and open Internet. So while a record number of Chinese people are logging online, they certainly can’t read or watch anything they choose.
While China had promised to increase Internet freedom during the Olympics, many of those promises have not been kept. The government vowed to relax Internet restrictions for foreign journalists, and finally complied only after intense international pressure, making some previously blocked sites available. Chinese Internet users, however, still face the same firewalls.
China maintains control over Internet users by blocking access to a wide range of Web sites and online activities it believes are a threat to the security of the state. To accomplish this monumental task, the government has created an elaborate system of filters, commonly referred to as “the Great Firewall of China,” using technology called deep packet inspection or DPI.
When an Internet provider installs DPI equipment, it allows them (or a third party) to see everything you do on the Internet. DPI technology has been in the U.S. news recently, as ISPs have begun using it to track customer activities for targeted advertising. But two U.S. broadband providers were using this technology for purposes that mirror China’s to block online content. Which American providers do such a thing? None other than Comcast and Cox, two Net Neutrality violators.
The companies have installed DPI equipment to block Internet communications they don’t like using reset packets (as China does). As the Electronic Frontier Foundation explained, their use of reset packets is akin to “a telephone operator that interrupts a phone conversation, impersonating the voice of each party to tell the other that ‘this call is over, I’m hanging up.’” While legitimate purposes exist for the reset command, only these two companies and malicious hackers use it as a third party to interrupt people’s communication.
Comcast and Cox purchased the equipment from the corporation Sandvine, which hit the “on” switch to let the companies start violating Net Neutrality. Since Free Press filed a complaint with the FCC against Comcast for its illegal blocking, Sandvine has had a tough time. Their stock price has tanked and their biggest customer, Comcast, has had second thoughts.
As long as Sandvine’s business model is violating Net Neutrality, we consider this good news. A couple weeks ago, however, their stock price received a bump. How is this possible after the consumer win on Net Neutrality, with the FCC telling Comcast to stop blocking?
Sandvine simply looked to the Great Firewall of China. Feeling the heat in the U.S., Sandvine struck deals with China and two countries – Qatar and Kuwait – looking to follow China’s lead and prevent their citizens’ access to a free and open Internet.
As you’re watching the Olympics, in the rare instance that an announcer actually brings up the current lack of online freedom in China, remember that Comcast and Cox utilize the same technology to impose their vision of what the Internet should be. Unless we continue to organize and fight for our online freedom, your Internet provider will assert an increasing level of control over what you say and do on the Internet, and Net Neutrality will no longer exist.
Internet, and Net Neutrality will no longer exist.
link
The Beijing Olympics are underway with the spotlight on China. Unfortunately, our TV announcers are so awed by the grandeur of the spectacle that they are overlooking the country’s authoritarian regime and its stranglehold on free speech.
China now has the world’s largest number of Internet users, having recently surpassed the United States. This number, however, doesn’t account for whether the Chinese government allows for a free and open Internet. So while a record number of Chinese people are logging online, they certainly can’t read or watch anything they choose.
While China had promised to increase Internet freedom during the Olympics, many of those promises have not been kept. The government vowed to relax Internet restrictions for foreign journalists, and finally complied only after intense international pressure, making some previously blocked sites available. Chinese Internet users, however, still face the same firewalls.
China maintains control over Internet users by blocking access to a wide range of Web sites and online activities it believes are a threat to the security of the state. To accomplish this monumental task, the government has created an elaborate system of filters, commonly referred to as “the Great Firewall of China,” using technology called deep packet inspection or DPI.
When an Internet provider installs DPI equipment, it allows them (or a third party) to see everything you do on the Internet. DPI technology has been in the U.S. news recently, as ISPs have begun using it to track customer activities for targeted advertising. But two U.S. broadband providers were using this technology for purposes that mirror China’s to block online content. Which American providers do such a thing? None other than Comcast and Cox, two Net Neutrality violators.
The companies have installed DPI equipment to block Internet communications they don’t like using reset packets (as China does). As the Electronic Frontier Foundation explained, their use of reset packets is akin to “a telephone operator that interrupts a phone conversation, impersonating the voice of each party to tell the other that ‘this call is over, I’m hanging up.’” While legitimate purposes exist for the reset command, only these two companies and malicious hackers use it as a third party to interrupt people’s communication.
Comcast and Cox purchased the equipment from the corporation Sandvine, which hit the “on” switch to let the companies start violating Net Neutrality. Since Free Press filed a complaint with the FCC against Comcast for its illegal blocking, Sandvine has had a tough time. Their stock price has tanked and their biggest customer, Comcast, has had second thoughts.
As long as Sandvine’s business model is violating Net Neutrality, we consider this good news. A couple weeks ago, however, their stock price received a bump. How is this possible after the consumer win on Net Neutrality, with the FCC telling Comcast to stop blocking?
Sandvine simply looked to the Great Firewall of China. Feeling the heat in the U.S., Sandvine struck deals with China and two countries – Qatar and Kuwait – looking to follow China’s lead and prevent their citizens’ access to a free and open Internet.
As you’re watching the Olympics, in the rare instance that an announcer actually brings up the current lack of online freedom in China, remember that Comcast and Cox utilize the same technology to impose their vision of what the Internet should be. Unless we continue to organize and fight for our online freedom, your Internet provider will assert an increasing level of control over what you say and do on the Internet, and Net Neutrality will no longer exist.
Internet, and Net Neutrality will no longer exist.
link
A spider web and I'm caught in the middle
I turned to run
The thought of all the stupid things I've done
And I, well if I ever caused you trouble
O no, I never meant to do you harm
The thought of all the stupid things I've done
And I, well if I ever caused you trouble
O no, I never meant to do you harm
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