A U-shaped platform on which instruments and equipment are mounted. The pallets are directly exposed to space and covered with aluminium. They are controlled by astronauts and hold large instruments for experiments or systems that require sweeping views, such as telescopes, sensors, and antennae. The pallets were developed for Spacelab, with up to five flown during a single mission. If an igloo (pressurized service container) is attached, a pallet can supply electrical power, cool equipment, and provide connections for acquiring data from experiments.