The Stratolab program was a series of manned balloon flights undertaken by the U.S. Navy's Office of Naval Research to perform high-altitude experiments. The first flight of the Stratolab program took place on August 10, 1956 and set an altitude record for an open gondola. Stratolab-High 5 launched on May 4, 1961 from the deck of the aircraft carrier USS Antietam in the Gulf of Mexico. The pilot was Commander Malcolm D. Ross of the Office of Naval Research and the observer was Lieutenant Commander Victor A. Prather, Jr. of the Naval Medical Research Institute. One of the objectives of Stratolab-High 5 was to test space suits above 99% of the Earth's atmosphere. The suits worn by Ross and Prather were slightly modified Mercury space suits that had the controls and gauges placed where they were easily reached and read and contained a liquid mixture that could be sipped through a tube fixed inside the helmet. Both men were wired to record physiological data which was automatically relayed to medical personnel aboard the aircraft carrier. The gondola, designed by Winzen Research, Inc. of Minneapolis, Minnesota, was fitted with floats for an ocean landing and carried two radios. The balloon was the largest ever used for manned flight with a volume of 10 million cubic feet. The complete craft, balloon and gondola, was 483 feet tall at launch. Stratolab-High 5 set an altitude record for manned balloon flight by reaching 113,740 feet during the mission. Stratolab High-5 landed safely in the Gulf of Mexico at the end of the flight and Ross was recovered safely by helicopters but Prather was killed when he slipped off the hoist and drowned.