Iris was a small, two-stage, solid-propellant sounding rocket designed to explore the upper atmosphere. Development of the Iris sounding rocket had begun at Naval Research Laboratory (NRL) prior to the transfer of NRL's Rocket-Sonde group to NASA. Iris was built by the Atlantic Research Corp. for the Naval Bureau of Ordnance, with NRL monitoring the design, the production, and the payload. The development of the rocket was completed by NASA, and the first NASA firing took place at Wallops Island on 22 July 1960. Iris was capable of lifting 45 kilograms (100 pounds) to an altitude of about 320 km (200 mi). NASA has not used the Iris rocket since 1962.