Friday, Jul 25, 2008
Started as a weather-tracking program in 1978, the Argos System provided a way to monitor surface temperature and barometric pressure in the ocean via transmitters stationed on floating buoys. But in the early '80s biologists began using the system to press the boundaries of what can be tracked and learned remotely from animals.
Biologists have long tracked animals via radio transmitters with hand-held receivers, stalking their subjects by flying over them in helicopters or following them in vehicles. But this approach obviously has its limits for birds that migrate thousands of miles, or a polar bear whose movements over ice and snow in subzero temperatures can make following along an impossible ordeal in bad weather. Ironically, satellite tracking can make the study of animal behavior into a sit-in-front-of-your-monitor experience far from fresh air and dirt.
In early studies, only large animals like polar bears could comfortably carry the heavy transmitters necessary for tracking. But as the technology got smaller and lighter and the power requirements shrank -- it can take as little as a quarter of a watt to send these messages -- Debbie Shaw, deputy director of information technology for Service Argos in Maryland, says that the biological field has exploded. Some transmitters are now as small as 15 grams, making surgical implantation a possibility.
A satellite picks up the pulse of the transmitters in about a 10-minute window. The satellites circling near the equator make it around the earth six or seven times a day, while the ones near the poles (given the shorter latitude) make their trip 14 times a day. As the satellite approaches a transmitter it picks up the signal at different frequencies depending on its proximity to the object. Using the Doppler effect, the longitude and latitude of the transmitter can be calculated with accuracy as close as 150 meters. The satellite dumps the data it receives at any of three main ground stations in Wallops Island, Va.; Gilmore Creek, Alaska and Lannion, France, where it then gets sent along to the scientists.
As for the effect on the animals, don't start cooking up dire images of nature marred by scientific hubris. Even the individual animal subjects aren't saddled with the transmitter for their entire lifespan. In the case of the bald eagles the Santa Cruz researchers track, for example, the backpacks are attached with a wax cotton embroidery thread that's designed to degrade and fall off roughly when the battery-powered transmitter runs out of juice.
Monitoring humans in the same way is mostly off-limits as far as Argos is concerned. A not-for-profit with an environmental mandate, the system is used to track humans only when they are in some kind of "loss of life" situation. "What I call crazy projects," Shaw explains. Those brave (or foolish) adventurers who embark on plans to walk to the North Pole in a month or sail around the world in a boat by themselves often have Argos with them to send an alarm and help out in an emergency rescue.
Over the years, as many mysteries of nature have been solved by the data stream from the sky (Where do spectacled eider ducks go in winter anyway?), new ones have sprung up to vex researchers. Take the puzzling case of Chessie, the West Indian manatee.
It seems Chessie took a long swim one summer from Florida up the coastal waters of the Atlantic to the Chesapeake Bay. He then explored the Long Island Sound and the East River, before cruising over to New England. Since manatees weren't known to venture farther north than Virginia, the 28-mile-a-day sea trek was cause for excitement and concern among biologists tracking the manatee via satellite.
But soon marine biologists became so worried that Chessie wouldn't make it back to Florida in time for winter that they interfered with their own experiment, captured the marine mammal and transported him back to warmer waters. "They didn't think he would make it," Shaw explains. But then the following year, the manatee with wanderlust took off again on the same trip to the Chesapeake Bay. Go figure.
The eye-opener in the Santa Cruz Predatory Bird Research Group's bald eagle study has been that individual birds take almost exactly the same route at the same time each year. "It was completely surprising," says Linthicum. "Bird X would be on the same river in Southern Alberta at the same time."
It makes you wonder what mysteries of human behavior will be revealed when the commercial applications of technologies similar to Argos become available, as they are beginning to be. No doubt the same exhibitionists who broadcast their lives on webcams will be lining up to have their every move tracked and broadcast on the Web to their devoted fans. And just as we can now follow the individual migration pattern of a single bald eagle named Alegria or an Alaskan caribou named Blixen on the Web, how long before a GPS-enabled descendent of Jennycam starts sending out daily e-mail updates of her longitude and latitude, heart rate and body temperature? After all, isn't it time that Web performance art caught up with science, and we followed our feathered and four-legged friends out of the primordial ooze into the digital age?
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