Right now, millions of objects are whizzing around Earth faster than speeding bullets. Much of this is celestial garbage — remnants of past missions and cosmic collisions that have taken place over half a century.
Dead satellites. Spent rocket stages. Astronauts' long-lost equipment.
To keep watch over this vast orbiting junkyard, the Air Force has awarded a $914.7-million contract to Lockheed Martin Corp. to develop a surveillance system that will provide a continuous watch over what's up there.
The system will enable the U.S. government to detect and track objects as they circle the globe, particularly the most congested areas of space.
The clouds of debris hurtle through the cosmos at up to 17,500 mph. At that speed, even a small piece of junk is a menace to the International Space Station and satellites that are fundamental to the economy, military and our modern way of life.
Currently, every launch — whether it's of astronauts, spy satellites or digital television satellites — needs to be carefully synchronized so it isn't swiftly obliterated by the minefield of orbiting debris.
The global community has discussed cleanup measures in the past. But before a solution is proposed, experts need to understand what exactly is orbiting Earth and the danger it poses.
Air Force officials say the new surveillance system from Lockheed, dubbed "Space Fence," is a step in that direction.
"Previously, the Air Force could only track and identify items the size of a basketball," said Dana Whalley, the government's program manager. "With the new system, we'll be able to identify items down to the size of a softball. This will significantly increase our capability."
Researchers have cataloged more than 23,000 items that are bigger than a basketball, but just a scant 1,100 are functioning spacecraft. NASA estimates there are many millions of pieces of debris so small that they can't be tracked.
Danger warnings are everywhere. Astronauts have had to take refuge in the escape capsules aboard the space station for fear of threatening debris. The space shuttle often returned from orbit with nicks cut into it by passing paint flecks or other fragments.
A 2007 study from the National Research Council showed that the amount of space junk is at a "tipping point."
That same year, China blasted a missile at an old weather satellite and destroyed it — at the same time adding more than 3,000 pieces of debris. In 2009, a defunct Russian satellite collided with and destroyed a functioning U.S. commercial satellite, creating an additional 2,000 scraps of space trash.
A big concern is that the debris will continue smashing into one another and eventually set off a domino effect that results in a "collision cascade." That sort of incident was depicted in the Oscar-winning motion picture "Gravity."
"I don't want to say that a Hollywood movie is a reflection of reality," Whalley said. "But they did do a good job of showing what a debris field looks like as it moves through space."
It is a real threat, according to Dave Baiocchi and William Welser, researchers at Santa Monica-based Rand Corp. who have written on space debris for the last six years. But it is important to remember that outer space is a big place and some regions are more crowded than others, they say.
Consider the rush-hour traffic among particles about 600 miles above Earth's surface. This is where Earth imagery spacecraft — like those used in services such as Google Earth — have created a high-traffic area of orbit.
"We need to understand what's going on in those areas and assess the risk," Welser said. "That's why programs like the Space Fence are so important. It's the first step."
Once the world understands what, if any, problems there are with the orbiting debris, then decisions can be made about what to do with it, and whether it's worth the millions of dollars to try to clean it up.
But nations have come a long way in limiting the amount of orbital pollution over the last decade or so, analysts say.
U.N. member countries adopted space debris mitigation guidelines in 2008. They call for the removal of defunct spacecraft from low-Earth orbit, the area most crowded with satellites.
Lens caps on satellite cameras are now tethered so they don't float away. Rocket makers design stages to fall away and burn up in re-entry, so they don't stay in orbit.
Those sorts of measures were needed because more people than ever rely on space for communication, navigation and entertainment. For instance, the satellite TV market in the U.S. has exploded by about 35 million subscribers over the past two decades.
Until 2000, few civilian devices could even read GPS signals. Now, hundreds of millions of people use GPS daily through their cellphones.
The Space Fence will replace the current system, Space Surveillance Network, a worldwide network of 25 space surveillance sensors — radar and optical telescopes. The aging system has been spotting objects since 1957, when the Soviet Union launched Sputnik, triggering the space race.
Space Fence will use a higher wavelength frequency capable of detecting small objects in low-Earth orbit. It provides continuous radar pulses, essentially forming a "fence" that detects, tracks and determines orbits of objects as they pass through the pulse field.
Lockheed will begin breaking ground at Kwajalein Atoll, an island located more than 2,400 miles southwest of Honolulu, in six months. The system's initial operational capability is set for 2018.
"Our system will do precision tracking," said Steve Bruce, a Lockheed vice president of space systems. "That's what makes it so good."
The system is being designed by Lockheed engineers at locations across the country.
The Air Force Space Command's Space and Missile Systems Center, at Los Angeles Air Force Base, is in charge of acquiring and developing the system.
The radar installation will be made up of small antennas clustered into an array about the size of a basketball court. It will all sit under a dome made of Kevlar on Kwajalein Atoll.
There's also an option for a follow-up contract to build a second radar installation in western Australia.
"The Air Force wants to protect its assets in space," Bruce said. "We'll be able to help them with that."