The potential of gliders
Lacking a motor or propeller, gliders zigzag up and down through the water using a set of fins to translate changes in buoyancy into lateral motion. Their top speed is about one-half mile per hour. A small battery powers the buoyancy changes by forcing mineral oil in and out of an inflatable bladder. Moving the battery fore or aft within the hull shifts the center of gravity to control pitch, rotating it from side to side controls roll.
Smith says that gliders bring several potential benefits to ocean research. For one, because they're propelled by buoyancy changes rather than an energy-hungry motor, they can remain in the water for months at a time before needing a recharge (the current world record is a 4,500-mile transatlantic crossing that lasted 221 days, using the equivalent power of just 3 Christmas tree lights). Motor-driven underwater robots are limited to missions of a few days at most.
A glider's small size and simplicity (with only a few moving parts) also makes it relatively inexpensive to own and operate, especially compared to the costs of ship-based ocean research. Smith's gliderdeveloped at the Applied Physics Laboratory at the University of Washington and now sold commercially by iRobot, Inc. (maker of the Roomba vacuum cleaning robot)cost $150,000. A single ship-day, including costs for fuel and crew, can run up to $60,000.
Dr. Mark Patterson, head of the Autonomous Systems Laboratory at VIMS and developer of the Fetch autonomous underwater vehicle (AUV), notes that gliders and other AUVs hold great promise for solving one of the oldest problems in oceanography: the fact that "the ocean changes faster than we have the ability to observe."
"Traditional ship-based studies can only provide snapshots of the constantly changing ocea
|Contact: David Malmquist|
Virginia Institute of Marine Science