Hovering about

A new robotic underwater vehicle can hover in place like a helicopter - an invaluable asset for deepwater oil explorers, marine archaeologists and oceanographers.

Developed by researchers at MIT, the new craft, called Odyssey IV, is the latest in a series of small, inexpensive, artificially intelligent submarines developed over the last two decades by the MIT Sea Grant College Program's Autonomous Underwater Vehicles Laboratory.

While previous Odyssey vehicles could only operate while continuously moving forward, the Odyssey IV, which has just completed sea trials off Woods Hole, Massachusetts, doesn't have that problem.

It can move through the deep ocean, up to 6,000m down, stopping anywhere in the water column and constantly correcting for currents and obstacles. Navigating to its preprogrammed destination, it can hover in place, making detailed inspections of the footings of an offshore oil platform, or photographing the flora and fauna around an undersea vent.

'In the past, you could only fly over a scene, take a picture, then fly over again and take another picture. Now, I can stop over a scene that's of interest, and stay and make measurements,' said Chryssostomos Chryssostomidis, director of the MIT Sea Grant Program.

This summer, the new craft has been demonstrating its abilities on its first scientific mission, a study of the George's Bank area of the Gulf of Maine, which is important to the region's commercial fisheries.

The craft's capabilities go beyond just looking at objects. 'Like a giant helicopter, it can pick up cargo underwater,' Chryssostomidis said. 'Now, we can visit an oil well, pick up a sample and bring it back to shore.'

Not only can the craft hover, it can move quickly, up to 2m per second going straight ahead. Both its speed and its ability to stop in place are achieved through the combined action of fins and thrusters on each side, and at the bow and stern of the 2m-long craft.

Schematic shows Odyssey IV, a small, inexpensive, MIT-designed robotic submarine that can hover in place like a helicopter