Although undeniably graceful, gliding has until now been suitable only for pleasure flights. But this is changing, as researchers enhance the capabilities of unmanned aircraft. Small unmanned gliders will soon be able to stay overhead for weeks, acting as communications relays, keeping a persistent eye on the ground below and even tracking marine animals thousands of kilometers across the ocean. One such glider is being developed at the Naval Postgraduate School in California. It needs an electric propeller to take off, but having reached a reasonable altitude the craft can fly all day just by riding rising currents of warm air. Kevin Jones, who is in charge of the project, says he has often found the craft sharing the air with some eagles. On some occasions, indeed, the birds found that the spiral air they were attempting to join were too weak for their weight, as the craft is more efficient at gliding than they are.