Up where the U-2 plane flies - at 70,000 feet - pilots can see the curvature of the earth below and the darkness of space above. They can also peer penetratingly into enemy territory - and have been doing so for four decades.
Now Saddam Hussein has threatened to shoot down the UN-controlled planes plying the skies above Iraq, and world attention has returned to the plane dubbed the "Dragon Lady."
The U-2s were originally developed by the CIA to spy on the former Soviet Union before the United States had surveillance satellites in orbit.
They first flew in August 1955 and remain a key part of the Air Force fleet. Despite their age, the U-2s are more effective than high-tech spy satellites, because satellites pass by a target area only several times a day - allowing easier evasion of their prying eyes - while U-2s can fly constantly.
Long, wide, straight wings give the U-2s glider-like characteristics. They fly at a relatively slow 430 miles per hour and cost $34 million per plane.
Over Iraq, the camera-equipped aircraft are seeking answers to incongruities not easily explained - large water pipes going into small buildings, a perimeter fence appearing suddenly around a nondescript facility, large numbers of cars parking around a purported warehouse.
But the slow spy planes also are vulnerable, and that presents the United Nations and the Clinton administration with a dilemma: Risk conflict with Iraq or forgo crucial information on Iraq's weapons of mass destruction. "It's no accident that Saddam wants to poke our eyes out, and we don't want him to," says John Pike of the Federation of American Scientists.
A map displayed last week by Iraqi Deputy Prime Minister Tariq Aziz showing recent U-2 flight paths indicated clearly that Iraq can track the planes. Iraq's arsenal has Soviet-built SA-2 surface-to-air missiles that can reach targets at U-2 altitude, but the odds of a hit are long. A missile becomes less maneuverable in the thin air, but the spy plane is capable of making tight, evasive turns. Seven U-2s have been shot down: the one over the Soviet Union flown by Francis Gary Powers, five over China, and one over Cuba.
"It's a pretty good score when you consider the plane has been flying for 40 years," says Chris Pocock author of two U-2 books. "The last one downed was in 1967, and the U-2 flew over Iraq during Desert Storm."
Experts say the U-2 is improved from the plane shot down by the Soviet Union in 1960. To fire a missile at a U-2, Iraq must "paint" the plane with radar. That opens the Iraqi missile battery to attack by US radar-seeking missiles.
"While there's obviously a danger to the U-2 pilot, there is a danger to the Iraqi air-defense operator who's foolish enough to turn on his radar," Pike says. "That's why the Iraqi air defense collapsed during the Gulf War: Iraqi operators knew if they turned their radar on, we would kill them."