Victor Prather - The Flight

The Flight

On May 4, 1961, at 7:08 am, Victor Prather, along with Cdr. Malcolm Ross, ascended in Strato-Lab High V from the flight deck of the USS Antietam (CV-36) to an altitude of 113,720 feet (34,668 meters) to test the Navy's Mark IV full-pressure suit.

The balloon, built by Winzen Research Inc. of Minneapolis, Minnesota, was constructed of polyethylene plastic only .001 inches (0.025 mm) thick. The 10 million cubic feet (280,000 m3) balloon envelope was the largest that had ever been successfully launched, expanding to 300 feet (91 m) in diameter when fully inflated. Beneath the balloon hung a large parachute and then the gondola. To control temperature, the gondola was protected by special venetian blinds, but otherwise open to space. Balloon, parachute, gondola, and a trailing antenna made a craft close to 500 feet (150 m) tall.

The primary objective of the flight was to test the Mark IV full-pressure suit. The suit was manufactured by B. F. Goodrich of neoprene and weighed only 20 pounds (9.1 kg). 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 −94 °C (−137 °F) when they passed 53,000 feet (16,000 m) at 8:10 am. Strato-Lab V reached maximum elevation of 113,740 feet (34,670 m) at 9:47 am, where the temperature was −29 °C (−20 °F) and the air pressure was .09 pounds per square inch (620 Pa). 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 140 miles (230 km). 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 am in the Gulf of Mexico. A hovering helicopter lowered a rescue hook (or harness), and although Ross slipped partially out of it, he was able to recover without falling completely into the water. A few minutes later the helicopter returned to retrieve Prather. Prather climbed onto the rescue hook but was unable to secure himself. When the helicopter jerked upwards, he slipped off into the ocean. His flight suit then flooded, and he drowned before Navy divers could rescue him. Prather's body was never recovered.