High over the Mojave desert, the Pentagon has been quietly testing a new generation of unmanned plane that flies higher, soars longer and runs greener than anything in the Pentagon's arsenal.
"This will really change the way we think about aviation," Assistant Secretary of Defense for Research and Engineering Zachary Lemnios told ABC News. "And it's going to open up an entirely new future."
The Global Observer, made by Monrovia, Calif.-based AeroVironment Inc., is bigger than a 767, flies in the stratosphere up to 65,000 feet, twice as high as Mount Everest -- out of sight and out of range of most anti-aircraft missiles. From there it will be able to see 600 miles in every direction, enough to cover the entire country of Afghanistan.
Earlier this month, the manufacturer gave ABC News an exclusive look, including video of the first test of a plane, which is powered entirely by liquid hydrogen fuel -- light enough to power the drone for a week at a time, far longer than anything in use today.
"It uses hydrogen for fuel, which has three times the energy density of gasoline, which enables it to fly much longer and at much lower costs and -- oh, by the way, has zero emissions," AeroVironment CEO Tim Conver told ABC News in an interview at the plane's hangar at Edwards Air Force Base in California.
It emits only water vapor.
The aircraft weighs about as much as a large SUV, but in order for it to fly so high for so long, the wing span has to be enormous -- about half a football field. That way even when you can't see it, it can see you.
AeroVironment is best known for electric car chargers and hand-launched, 1- to 2-foot-long unmanned aircraft -- some, like the Switchblade, lethal.
"It turns into a guided missile," AeroVironment's Steve Gitlin said, "and it'll follow the target if the target moves."
The new drone takes that unmanned capability much further, doing the work of a satellite for just tens of millions of dollars -- some analysts say it would cost about $30 million -- compared with hundreds of millions to $1 billion for a satellite. Unlike satellites, it can be up within hours and has the ability to instantly reposition.
The plane orbits above a target for a week at a time. In addition to on-board cameras that offer an unblinking eye, communications equipment offers cell phone, TV and broadband Internet for the same area.
When it refuels, a second plane takes its place. The military would swap out the plane every week, so it has constant surveillance.
The military sees the new drone as a cheaper way to put cameras and communications over Iraq and Afghanistan and more.
But the Global Observer doesn't just have military applications -- it has potential civilian uses, too.
It has an interchangeable payload that can carry cameras or communications equipment. The company initially envisioned it as a cheap way to supply broadband Internet, television and phone service cheaply in the Third World.
Then came the terror attacks of 9/11. The company immediately turned to the military, which quickly grew interested.
"This is one of those things you see happen a few times in your career, and you sort of look at it and you say at that moment: Things have changed and that would really open up a new vista for the department and the nation," the Pentagon's Lemnios said. "It's a milestone in aviation, absolutely -- no question."
The company says the plane could have restored communications within hours on 9/11.
"All the cell towers in that whole area of New York were out," Conver said. "Immediately a platform like this could be flown over and parked over New York and restate the communications infrastructure."
It has the potential for a more controversial use: border patrol.
"Certainly if one wanted to see what was going on their border, looking at a 600-mile swath or area from one point would be a good way to do that," Conver told ABC.
The plane could also track dangerous storms, Western wildfires, or -- perched high overhead like a silent guardian angel in a disaster like Hurricane Katrina -- link first responders and searching for survivors in those first, precious hours that can mean the difference between life and death.