was manufactured by B. F. Goodrich of neoprene and weighed only . The Mark IV suit overcame problems of weight, bulk, ventilation, air and water tightness, mobility, temperature control, and survival capabilities so well that NASA selected a modified version for use by the Project Mercury astronauts. Malcolm Ross and Victor Prather were exposed to temperatures as low as when they passed at 8:10 am. Strato-Lab V reached maximum elevation of at 9:47 am, where the temperature was and the air pressure was . At that altitude without a space suit, a person would lose consciousness in seconds. The May 4 flight was the most severe test of the Mark IV suit that was ever conducted. The flight lasted 9 hours 54 minutes and covered a horizontal distance of . As they descended, the balloonists opened their face masks when they reached an elevation where they could breathe. Strato-Lab V landed at 4:02 pm in the Gulf of Mexico. The mission plan was to use a boat to retrieve the balloonists in the event that the gondola landed in the water instead of on the flight deck of the carrier. This had been rehearsed. However, without orders to do so, the crew in a hovering helicopter lowered a hook. Commander Ross invited Prather to go first, but he declined. Ross stepped into the hook contrary to proper procedure and slipped partially out of it, but he was able to recover without falling completely into the water. A few minutes later, when a hook was lowered to retrieve Prather, he stood on a float attached to the gondola and grasped the rescue line. When he stepped into the hook, the trailing foot pushed the gondola away, and he fell backwards three feet into the water. The helicopter crew assumed that the flight suit was watertight, which it would have been if the face plate was still closed, and did not effect an immediate rescue. Because the face plate was open, Prather's flight suit flooded, and he drowned before Navy divers could rescue him. After the flight Shortly after Prather's death, President John F. Kennedy phoned Prather's widow, Virginia Merritt, and she arrived at the White House with her children, Marla Lee Prather and Victor A. Prather III. Kennedy posthumously awarded Victor Prather the Navy Distinguished Flying Cross for 'heroism and extraordinary achievement'. The balloonists were also awarded the 1961 Harmon Trophy