NASA A 2010 NASA map of objects in low Earth orbit.

Space might not yet have Washington Beltway-style traffic jams, but with more than 21,000 objects in orbit it's becoming crowded, creating what the Defense Department terms a new urgency to improve its awareness of what is floating around the Earth, said top Air Force commanders.

Air Force Lt. Gen. Larry James, commander of the U.S. Strategic Command's Joint Functional Component Command for Space, told the Senate's Strategic Forces Subcommittee on March 10 that the number of objects in space increased 1,700 since last year to 21,500.

The material orbiting the Earth include 1,100 satellites operated by more than 60 countries, 10,000 pieces of debris, 3,700 inoperable satellites and rocket pieces, and 6,800 unknown objects. James said the objects pose potential threats to Defense systems used for communications, surveillance, weather and positioning.

The crowded orbits have led to one known collision, when a 2,000-pound defunct Russian satellite crashed into and destroyed a 1,235-pound iridium communications satellite in February 2009. The collision highlights the need to improve space situational awareness, Gen. Robert Kehler, head of the Air Force Space Command, told the hearing.

Defense currently monitors space using a decades-old system called a Space Fence, which the Navy designed to track satellites that went into operation in 1965. In 2004, the Air Force took over the Space Fence, which uses three VHF transmitters and six receivers all located in the United States to detect basketball-sized objects as far away as 15,000 miles. The system collects an average of 5 million individual observations every month.

The Air Force plans to replace the Space Fence with a $3 billion system that will use three radars positioned worldwide. The system will be able to eyeball smaller objects. The Air Force has not chosen the sites to place the radars, but it is considering one location in Australia.

The 850th Electronic Systems Group at the Air Force Electronic Systems Center at Hanscom Air Force Base, Mass., awarded a $30 million contract each to Lockheed Martin Corp., Northrop Grumman Corp. and Raytheon last July to develop a concept for the new Space Fence. The center plans to make the award in 2011 to one of the companies to build the new system.

When the center made the concept awards, Linda Haines, program manager for the Space Fence at Hanscom, said the new system would be the most precise in the space situational surveillance network.

But since the award, the National Space Situational Awareness Community (SSA), which consists of Defense, NASA, the National Oceanic and Atmospheric Administration, and intelligence agencies, has discovered what it described as highly classified gaps in the planned SSA architecture.

To create a better system, the Air Force Space and Missile Systems Center in Los Angeles asked industry on March 16 for space- and terrestrial-based plans to better monitor space objects.

Officials at the Space and Missile Systems Center said they needed help to mitigate specific gaps in the National Space Situational Awareness architecture, but did not disclose details because they were classified Secret and Top Secret. Responses are due June 3.