Photos: Unmanned vehicles take to air, land and sea

This six-wheeled unmanned surface vehicle, under development for the U.S. Army, is designed to be configured in three ways: as an assault machine equipped with rapid-fire weapons (model pictured here), as an equipment-transporter and as a mine detector. At 2.5 tons, the MULE, as it is known (short for Multifunction Utility/Logistics and Equipment) is light by military vehicle standards and can be carried inside standard cargo airplanes and helicopters. Lockheed Martin and subcontractors MillenWorks and BAE Systems have been working on a prototype that recently was able to climb a 30-inch step and bridge a 70-inch gap without extra help from the vehicle's operator, which the company said indicates it may be able to stand up to some serious off-roading. It's designed as a complement to--not a replacement for--humans on the ground, with planned availability by 2013.