Based at times in Area 51, the U-2 spyplane tested the very limits of human endurance and Cold War technology when it first flew in 1955. Pilots would fly the high-altitude spy craft at above 70,000 feet for hours at a time, taking photos of developments below. One such flight revealed the buildup of Soviet nuclear missiles in Cuba, and sparked the Cuban Missile Crisis. With the advent of drones, and specifically the long-endurance high-altitude Global Hawk, the U-2's days in service might be numbered. A plan by Lockheed wants convert the venerable spy plane of the past into a modern surveillance robot of the future.

Global Hawk and U-2 programs have been rivals for years, with the old-timer flying higher, carrying more sensors, and offering defensive countermeasures, while the younger drone far surpasses it in endurance. Global Hawks can fly for 24 hours continuously, twice that of the mandated 12-hour limit for onboard U-2 pilots, and the Global Hawk can change pilots mid-course, as its remote controls allow crew changes throughout the flight time.