Science and Technology News

Tuesday, February 23, 2010

HAARP’s Antenna Array: The Test Kitchen in the Sky

By John Ohab

February 23, 2010 - Dr. Todd Pederson at the HAARP Antenna Array north of Gakona, Alaska.  Dr. Todd Pedersen is a space physicist serving with the Air Force Research Laboratory, Space Vehicles Directorate’s, Battlespace Environment Division, Hanscom Air Force Base, Mass. He got his start as an experimenter early in life playing with magnets, wires, and other fun stuff salvaged from old radios, motors, and cars.

It’s the week before Thanksgiving, but the temperature is already 37 degrees below zero. The dashboard lights dim as the rental car engine slowly turns over, but thankfully, it starts and I am on my way for another day.

Every bit of snow tracked into the car on my boots over the last two weeks is still there on the floorboards, frozen squeaky solid. It is enough if the heater will keep a spot on the windshield, in front of me, clear of snow and ice. The tires thump as I drive slowly up the hill—-they will go back to being round after they warm up a bit and can flex a little more, but for now, the side frozen flat against the ground all night stays flat.

The blue-gray twilight over the volcano reflects off the shiny ice covering the highway. In Japan, this mountain would overshadow Mt. Fuji, but here, looking out over the Wrangell-St. Elias National Park in south central Alaska, it’s just another 15,000 foot volcano. But I’m not here for the scenery, and certainly not here for the weather. I’m here for the ionosphere, and a huge 30-acre antenna array that lets us do experiments with it.

I arrive at the HAARP facility–the fancy name for the antenna array and its associated power supplies and instruments–40 minutes later, look at the latest readings from the instruments on the Web site, and start planning the details of the evening’s experiment.

The ionosphere is a plasma, created by sunlight, and in this part of the world, electrons shooting down to form the aurora. Unlike plasmas created in laboratories, light bulbs, and gift-shop gizmos here on Earth, the ionosphere isn’t trapped inside a bottle and has no walls to siphon off the particles. It’s the same problem as trying to make clouds in a jar. Instead of a cloud in the middle, all the moisture sticks to the edges and you just get foggy glass.

The big antenna out there sends out radio waves at just the right frequencies to resonate with the ionospheric plasma, kind of like wiggling a block of jello. When everything works just right, the wiggling can break the plasma up into long parallel strands like a handful of uncooked spaghetti. Only these noodles are 20 or 30 miles long and start 100 miles up. The same thing also happens naturally, as the ionosphere rises and falls and gets pushed around by currents in the solar wind and upper atmosphere.

As you might expect, the bundles of plasma spaghetti do not play nicely with radio waves passing through them, so an ionosphere full of these is unkind to global positioning system signals, radar beams, and satellite links our high-tech troops depend on to keep the pointy end pointed at the bad guys and the good guys safely out of harm’s way. The big antenna array out there is the only lab we have where we can actually study the ionosphere through controlled experiments–a test kitchen in the sky if you will.

Another glance at the Web site shows today’s ionosphere developing very nicely. Tonight, I’ll add a little FM sweep at 2.9 Megahertz to the recipe. It might be perfect with spaghetti.

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