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Could Plasma Bubble Have Doomed U.S. Copter in Afghanistan Battle?

Twelve years ago, a U.S. military rescue mission in Afghanistan went horribly wrong. A Chinook helicopter carrying U.S. troops failed to receive a crucial radio message and was shot down over the snow-covered peak of Takur Ghar.

But the radio failure was not caused by malfunctioning equipment. Instead, a giant, 62-mile-long (100-kilometer-long) "plasma bubble" made up of clouds of electrically charged particles was responsible for the communication blackout, new research suggests.

Michael Kelly, a researcher at the Johns Hopkins University Applied Physics Lab (APL), in Laurel, Maryland, started to put the pieces together after reading a journalist's account of the Battle of Takur Ghar. He suspected the radio failure was caused by a little-known space weather effect caused by these mysterious plasma bubbles. (10 Surprising Ways Weather Has Changed History)

Image: How plasma bubbles form
Tendrils of low-density, charged particles are called plasma bubbles, and turbulence at their edges can skew radio frequency waves passing through them. APL researchers provide evidence that plasma bubbles may have contributed to the communications outages during a 2002 Afghanistan battle. NASA

During daylight hours in the upper atmosphere, radiation beaming down from the sun rips electrons from their atoms. But once the sun sets, the electrons start recombining with their atoms. This recombination process happens faster in the lower atmosphere because there are heavier particles there, and electrons recombine faster with molecules than they do with single atoms. Since the plasma in this part of the atmosphere is less dense, it rises and burrows into the denser plasma above. This causes giant bubbles of charged particles to form, similar to the way air bubbles rise from a submerged diver.

The huge bubbles of charged particles can bend and warp radio waves. In 2002, the Chinook helicopter was flying over Afghanistan in the spring, which is the height of plasma bubble activity, Kelly said.

Military officers based in Bagram, Afghanistan, issued a fateful radio warning to the helicopter crew to stay away from al Qaeda forces on the mountaintop, but the message was scrambled and lost. The helicopter crash-landed, and seven individuals were killed.

Image: Map of the area of Operation Anaconda showing the Shahikot Valley and the peak Takur Ghar
A map of the area of Operation Anaconda showing the Shahikot Valley (outlined in blue) and the peak Takur Ghar, which rises to 3,191 meters (10,469 feet). The area is in Paktia Province in eastern Afghanistan. U.S. Army

To figure out what went wrong, Kelly and a team of researchers used data from a NASA satellite mission called TIMED, which launched in 2001 to study the composition of Earth's upper atmosphere. Their model showed that on March 4, 2002, a plasma bubble loomed above the unlucky helicopter. The mountainous terrain had likely already made the radio signals weak, and the presence of the plasma bubble could have interrupted this weakened signal, causing a complete radio blackout.

— Kelly Dickerson, LiveScience

This is a condensed version of a report from LiveScience. Read the full report. Follow Kelly Dickerson on Twitter. Follow us @livescience, Facebook & Google+.