Researchers at the Starfire Optical Range of the US Air Force's Phillips Laboratory have demonstrated an ultralow-power optical communications system designed for small satellites. The team tracked a small satellite prototype optically at an altitude of 103,000 ft with a 1.5-m telescope and illuminated the payload with a low-power near-infrared laser while within a 45° vertical cone. Passive equipment modulated the tracking laser beam and reflected it to the telescope, which detected the modulation. This technique eliminated the need for a transmitter on the satellite, making low-power communications possible.