While at San Diego, Prather completed courses in Aviation Medicine and qualifications in fixed wing and helicopter aircraft.

In 1960, Prather was transferred to Project RAM, a government program to test prototype space suits, at the Naval Medical Research Institute in Bethesda, Maryland.

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 (34,660 meters) to test the Navy's Mark IV full-pressure suit.

[3][4][5] The balloon, built by Winzen Research Inc. of Minneapolis, Minnesota, was constructed of polyethylene plastic only .001 inches (0.025 mm) thick.

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.

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).

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.

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.

[12] The altitude record for a manned balloon flight set by Prather and Ross in 1961 is still officially recognized by Fédération Aéronautique Internationale.