For example, a fleet of 100 Global Hawks in close to their current configuration would allow virtual 24-hour coverage of multiple hot spots anywhere on the globe. With a cost of about $25 million per drone and a total program cost of $2.5 billion, commanders could feel comfortable using them whenever needed.
Senior military officers say that what really set Predator and Global Hawk apart in Afghanistan is that Gen. Tommy Franks, the Operation Enduring Freedom commander, "owned" them. He and his air war commander decided where the UAVs went. And the drones got the intelligence product directly into their command centers.
At $3 million per Predator, the cost of losing one was low enough to have them loiter over Kandahar or other locations, looking for Taliban and Al Qaeda leadership.
The challenge for the 21st century, Air Force Secretary Roche says, is to "find moving targets" and "have persistent intelligence."
Why not just use space satellites? They don't tend to crash, and their technical capabilities are legendary. With imagery satellites, however, "tasking" is a cumbersome and competitive process of claiming space on a limited national system that must serve many customers. Also, the current imagery satellites only pass over the same spot on Earth about every three days.
Because they fly about 300 miles above the Earth, says Jeffrey Richelson of the National Security Archive in Washington, a leading expert on spy satellites, about 30 satellites would be needed to provide constant coverage of any one spot.
Given the cost of an advanced KH-11 satellite--about $1.5 billion, Richelson says, with an additional $300 million cost to boost each satellite into orbit--such a force would cost about $54 billion. That's more than 20 times the cost of the 100-strong Global Hawk force, with far less flexibility.
Unlike satellites, UAVs and their sensor packages can be modified and given new equipment to meet changing needs.
The cost and other advantages of UAVs are sure to be pressed hard in the enormous debate that has begun since President Bush reopened the Pentagon's coffers for the war on terror. According to the Defense Department's April 2001 "Roadmap" for UAV development, "UAVs may offer increased efficiencies in operations and support costs due to the reduced need to actually fly pilot proficiency and continuation training sorties."
UAVs currently suffer accidents at 10 to 100 times the rate of manned aircraft. But for every hour flown by a UAV, military aircraft fly 300 hours; that's because 95% of a manned aircraft's flight time is for air crew training.
UAV operators get most of their training in simulators, at significantly less expense.
Given that "force" is the Air Force's last name, it shouldn't be surprising that, although Predator and Global Hawk have been stars because of their surveillance duties, enthusiasm is shifting toward another system, the Unmanned Combat Aerial Vehicle, or UCAV.
If deployed at the end of the decade, UCAV would be the first true unmanned bomber, able to go into the most lethal air defense environment without fear of U.S. casualties.
Roche and others are truly taken with this capability. One senior commander in Enduring Freedom said that, with current (and future) Stealth aircraft, such as the F-22, under development along with UAVs, the military will be able to operate with acceptably low casualty rates against any postulated enemy.
But that assumes the UAV will remain cheap enough and simple enough to use routinely.
"I wouldn't want to lose the ability to just throw it away," one analyst says. If it gets too precious for that, he says, "then you won't take risk to actually fly it where it's needed."
William M. Arkin is a senior fellow at the Johns Hopkins University School of Advanced International Studies in Washington and an adjunct professor of the U.S. Air Force's School of Advanced Airpower Studies. He is a consultant to a number of nongovernmental organizations and writes military analysis articles as a special correspondent for The Times.