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Going To The Ends Of The Earth For Cosmic Rays: LSU Researchers Survive Antarctica

Date:
March 29, 2001
Source:
Louisiana State University
Summary:
Nine Louisiana State University researchers recently spent three months at a U.S. research station in McMurdo, Antarctica, trying to detect cosmic rays by sending a specially designed instrument to the top of the atmosphere via a giant helium balloon.

It's day 42 in Antarctica. The group has survived temperatures ranging from 35 degrees Fahrenheit to just below zero. They have learned to build snow walls, work as a team to navigate through blizzards and peacefully coexist with such indigenous wildlife as penguins and seals. Today's challenge: launching a helium balloon the size of a football stadium into the atmosphere.

No, these are not contestants from a future episode of television's Survivor. They are researchers from Louisiana State University. And they are not competing for a million dollars, but are literally going to the ends of the Earth to challenge some of the basic principles of science.

Nine LSU researchers recently spent three months at a U.S. research station in McMurdo, Antarctica, trying to detect cosmic rays by sending a specially designed instrument to the top of the atmosphere via a giant helium balloon. The researchers, members of the LSU Department of Physics and Astronomy, conducted their Advanced Thin Ionization Calorimeter Scientific Balloon Experiment, better known as the ATIC experiment, to learn how cosmic rays are powered.

However, much like the contestants on the hit TV show, the LSU team had to undergo medical tests before being allowed to make the trip. Then they flew to McMurdo in a military cargo plane and got a crash course in survival training. For a group of Louisianians used to heat, humidity and swamps, the ice and mountains of Antarctica were a challenge.

"When I stepped off the plane, I felt like I was on the big snow planet from The Empire Strikes Back," said Doug Granger, LSU research associate who handled computer networking for the experiment.

The project's goal was to collect data from outer space that would identify the energy levels of cosmic rays. Cosmic rays are atomic nuclei that move through the galaxy at almost the speed of light. These particles contain extremely high levels of energy, which most scientists previously attributed to supernovae, or exploding stars. However, further studies of supernovae and cosmic rays have led to some doubt about this theory.

Scientists are now finding discrepancies between the levels of energy they believe are being created by supernovae and the levels of energy in cosmic rays. It is not certain that there are enough supernova explosions to power all of the galaxy's cosmic rays. It could be that there is another, possibly unknown, phenomenon powering cosmic rays. Or perhaps scientists just don't fully understand supernovae yet. These questions led to the ATIC experiment, and the first step in finding the answers is to take a closer look at cosmic rays.

To observe the cosmic rays, the LSU scientists and their collaborators spent five years building an apparatus that would detect them and determine their identities and energy levels. The apparatus is housed in a spherical Kevlar shell that is just under seven feet in diameter and is covered with white insulation to reflect sunlight and stay as cool as possible.

As the apparatus floats through the atmosphere, cosmic rays pass through it and are detected and measured. Inside the sphere is a silicon detector, which identifies the atom from which the cosmic rays originated; carbon, which collides with the cosmic rays, initiating a release of energy; and scintillators, which convert the deposited energy into light, which is then measured to reveal the energy of the charged particles. Amplifiers convert those readings into digital numbers, which are read and stored by computers so they can be analyzed by scientists.

The next hurdle was to find a way to send the equipment into the atmosphere. So they devised a way to attach it to an unmanned, solar-powered helium balloon that was roughly the size of LSU's Tiger Stadium. The balloon was launched into the atmosphere and later brought back to Earth by the National Scientific Balloon Facility, which conducts specialized balloon launches and landings for scientists. The LSU team spent six weeks setting up, testing and preparing in Antarctica before they were ready to turn their equipment over to the balloon experts. Then they got nervous.

"The launch and the cut-down were both kind of nerve-wracking," said LSU research associate Michael Stewart, who served as a computer programmer and analyst during the trip. "You work on this project for years, and then you have to just hand it over to the crew from the balloon facility and hope it goes well."

It did go well. The balloon was launched without a hitch into the atmosphere, where it flew for 16 days at an altitude of approximately 120,000 feet. "On launch day everything went really well," said Leslie Mock, LSU research associate who worked as a data analyst during the experiment. "After years of working on this project, I watched the apparatus float up and disappear into the clouds. I had tears in my eyes."

The landing, or cut-down, which requires a plane to be in visual contact with the balloon so it can cut the balloon away from the detection apparatus, also went well, the scientists said. Once the apparatus had been cut from the balloon, it began to free-fall, triggering the opening of a parachute to help it land. The apparatus came down about 240 miles from where it took off and, as expected, sustained some minor damage from the landing.

It took the LSU team several days to reach the landing site, dismantle the apparatus and remove the computers and detection equipment. While the scientists personally carried home the data gathered by the experiment, they had to ship the rest of the equipment back to Louisiana. It was sent from Antarctica to California by cargo ship and is still en route from California to Louisiana by truck. The equipment is not due back at LSU until sometime in April or May.

But even then, the experiment will not be finished. Members of the LSU team predict that it will take more than a year to analyze the 45 billion bytes of data collected during the experiment. They will separate the types of atoms they detected, plot them on charts that show their energies and evaluate whether the results have proven the supernova theory or given rise to new hypotheses.

A number of other institutions are collaborating with LSU on this project, including Southern University in Baton Rouge, the University of Maryland, Marshall Space Flight Center, the U.S. Naval Research Laboratory, and universities and labs in Korea, Russia and Germany.

The LSU team is planning to fly the apparatus again in December 2002 to collect more data. They have to wait that long because they need to rebuild the apparatus, which is now dismantled and partially damaged. Several faculty members and students from the LSU Department of Physics and Astronomy, with the help of on-site machine and electronics shops, will have the instrument up and running again in time for the next flight.

There are many reasons why the researchers conducted the experiment in Antarctica. First, the summer winds at the South Pole are circumpolar. That is, they circulate around the pole in a near-perfect circle. This allowed the scientists to launch and land the balloon at nearly the same location, with the wind doing most of the work. Second, the balloon must avoid flying over cities.

This is not a problem in the desolate expanse of Antarctica. Also, many foreign nations will not allow an overhead balloon flight for fear that the U.S. is spying on them. Third, the circumpolar flight takes about two weeks. A flight in the U.S. could last only a couple of days because of so many large cities. The longer the flight, the more data is collected. And finally, Antarctica is considered international lands, a circumstance that cuts down on the need for such things as permits and permission to use another nation's airspace.

"There are a lot of questions about cosmic rays and supernovae, and information is the only way we can find the answers," said LSU professor John Wefel, who headed up the experiment. "We need to fly the biggest thing we can fly for as long as we can fly it, so we can gather as much data as possible," he said.

Although some of the LSU scientists stayed for only part of the Antarctica trip, others stayed for the entire three-month duration. Along with Granger, Stewart and Mock, other LSU researchers who went to Antarctica included T. Gregory Guzik, Joachim Isbert, Brad Price, Randy Gould, Doug Smith and Mark Wefel. In addition, local reporter Bill Rodman of WAFB-TV in Baton Rouge went along to document the trip and to provide data-link assistance.

Since it was summer in Antarctica while they were there, the team did not see the sun set during the entire trip. Summertime in Antarctica means six months of daylight and warmer temperatures – the only factors that make it possible to work in that climate at all.

However, the researchers said they did see a very friendly baby seal and an active volcano. They rode snowmobiles, boiled snow to make drinking water during a power outage and braved the cold one night when their heater broke. One member of the team even took the "polar plunge" – a quick swim in the frigid ocean that first requires cutting a hole through the ice.

Perhaps they belong on Survivor after all.


Story Source:

The above story is based on materials provided by Louisiana State University. Note: Materials may be edited for content and length.


Cite This Page:

Louisiana State University. "Going To The Ends Of The Earth For Cosmic Rays: LSU Researchers Survive Antarctica." ScienceDaily. ScienceDaily, 29 March 2001. <www.sciencedaily.com/releases/2001/03/010328075007.htm>.
Louisiana State University. (2001, March 29). Going To The Ends Of The Earth For Cosmic Rays: LSU Researchers Survive Antarctica. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2001/03/010328075007.htm
Louisiana State University. "Going To The Ends Of The Earth For Cosmic Rays: LSU Researchers Survive Antarctica." ScienceDaily. www.sciencedaily.com/releases/2001/03/010328075007.htm (accessed July 22, 2014).

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