Although the researchers aren't ready to toss Odyssey IV into the Gulf of Mexico or the Adriatic just yet, AUV Lab graduate student Jim Morash says the tests in the Alumni Pool have been encouraging. "It's very smooth and very steady in the water," he says.

Not only are AUVs starting to look as comfortable in the water as fish, but in the future they might start to move like them, too. Researchers from MIT's Bioinstrumentation Laboratory are working with scientists at Drexel, Harvard, and George Washington universities to develop a mechanical fin for aquatic maneuvera­bility. The group, led by Professor Ian Hunter and James Tangorra, PhD '03, who is now an assistant professor at Drexel, studied the pectoral (or forward) fins of the bluegill sunfish, which can maintain control in fast-moving streams and turbulent waters. Creating an artificial copy would be impractical; Tangorra notes that the bone structures inside it are controlled by 59 muscles. And the group's prototype fins are not as rugged as the thrusters on Odyssey IV. Still, they're lifelike and elegant. "They look like pieces of paper flowing back and forth in the water," says Tangorra.

To enable the mechanical fin to move like the real thing, Hunter, Tangorra, and the rest of their group worked with Timothy Swager, head of MIT's chemistry department, and his lab to develop new actuators based on conducting polymers that alter their shape depending on the electrical current. These actuators, or artificial muscles, could eventually be used in other machines, too.

As the bodies of these vehicles evolve, so do their brains. At the Center for Ocean Engineering, visiting scientist Michael Benjamin has successfully demonstrated that the autonomous navigation system he developed for a group of MIT's autonomous kayaks, or SCOUTs (surface craft for oceanographic and undersea testing), also works with undersea vehicles (see "Autonomous Kayaks," January/February 2007). This system generally hews to the same waypoint-following strategy that most AUVs employ. But now Benjamin is upgrading it so that it can capitalize on new acoustic communications technology that will help the AUVs talk to each other, and to buoys or boats on the surface--reducing much of the guesswork involved in underwater navigation.

But better communication is only part of the story. Benjamin also attributes the success of his system to lowered costs, which mean that he and a colleague can drag a pair of kayaks down to the Charles whenever they please. The result, he says, is that he can be more adventurous when writing the code--he's not limited to one test a year, during which everything has to go absolutely right. Lower costs also mean that more groups can experiment with AUVs. Add open-source software and open collaboration to the mix, he says, and you get exponential progress.

Such collaboration seems like a natural step for AUV research, which already draws on fields from mechanical engineering to AI. And in ­Chryssostomidis's view, the more collaborators, the better. "To be frank," he says, "there are enough challenges that we could put the whole of MIT to work on it."