Probing beneath the sea: Sending vessels into environments too harsh for humans poses challenges in communications, artificial intelligence, and power-supply technology

When a U.S Air Force B-52 bomber collided in midair with its refueling plane near Palomares, Spain, in 1966, a 20-megaton hydrogen bomb was released that wafted harmlessly under a parachute until it sank 870 meters deep in the Mediterranean Sea. For obvious reasons of national security and international politics, the U.S. Navy moved quickly to locate the undetonated bomb. It spliced some 300 meters of extra cable onto the tether of a submersible called the Cable Controlled Underwater Recovery Vehicle: an unmanned vehicle equipped with a television camera, a manipulator arm, and a control tether that attached the vehicle to a support ship. With the help of the unmanned submersible, the Navy salvaged the bomb within three months.