Robotic underwater gliders revealing secrets of the sea
By Tara Godvin
By Tara Godvin
Ocean scientists can now plunge into the middle of the sea without leaving their offices.
Six-foot, 100-pound underwater gliders are swimming the oceans of the world and dutifully sending data home on everything from whale calls to the massive waves produced by hurricanes.
"The ability to be in the ocean all the time and do it over a sustained period — people are doing it now. And this is revolutionary," said Oscar Schofield, professor at the Institute of Marine and Coastal Science at Rutgers University.
The gliders suck in and shoot out water to change their buoyancy and move up and down. Small wings on their missile-like bodies create lift to move horizontally.
Without a noisy propeller or engine, the gliders run silently and on very little power. A small battery pack can keep them gathering information 24 hours a day on one-month missions. They also can be programmed to surface and send data to land-based labs via satellite.
And while cost for a large research vessel can mount up at $15,000 per day, a single, reusable glider costs about $25,000.
Though the idea of such a device had been dreamed of for half a century, the winged gliders have only come into more common use in the past three years.
Five years ago, very few scientific labs had even one of the gliders. Today, as many as 15 labs across the country have up to 20 each to deploy on projects from the Mediterranean Sea to just off the New Jersey coast, Schofield said.
Several ocean scientists reported on the use of underwater gliders at a recent ocean sciences meeting in Honolulu sponsored by the American Geophysical Union.
Relatively light, easy to deploy and inexpensive, the gliders are not subject to violent surface conditions and have the ability to meander among sea creatures and ply the oceans in any weather, including hurricanes.
Mark Baumgartner, a scientist with the Woods Hole Oceanographic Institution, uses the gliders to observe whales. The standard technique for watching the mammals involves using high-powered binoculars from the deck of a ship to spot them as they surface for air.
Eric Terrill, director of the Coastal Observing Research and Development Center at the Scripps Institution of Oceanography, is exploiting the gliders' stamina in an attempt to better understand what fuels and changes the intensity of devastating hurricanes.
Working with the National Oceanic and Atmospheric Association on a project sponsored by the Office of Naval Research, Terrill's team has dropped the machines off ships and parachuted them from 1,500 feet off planes in the path of storms.
Sensors attached to the undersea gliders measure salinity and water temperature to 200 meters, and the height of the soaring waves created by the storms. By recording the sounds of the waves as they break, researchers also are hoping to find a new way to measure the speed of a storm's winds, he said.
Terrill said researchers were surprised when the nine gliders they sent into Hurricane Francis in 2004 continued to send information back to shore even at the height of the storm, which had winds of up to 135 mph.