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Rusty Dennen writes about the environment and the great outdoors.

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Dahlgren keeping an eye on dead satellite

Among those watching the demise of NASA’s defunct  Upper Atmosphere Research Satellite  are technicians overseeing the “space fence” at  the  Naval Support Facility Dahlgren in King George.  Specifically, the  20th Space Control Squadron, Detachment 1 , which oversees the fence, and the Distributed Space Command and Control-Dahlgren, whose technicians operate  and monitor it. Read my recent story.

For 50 years it  has kept track of all but the smallest objects–about 22,000 and counting–orbiting the Earth.  The fence is a giant radar system with three transmitters and six receivers positioned  along the 33rd parallel across the southern U.S., from Georgia to California. It can “see” objects as small as a basketball, and is used to monitor a growing swath of manmade space junk–like UARS–that is a potential danger to other satellites, astronauts and the International Space Station, not to mention people on the ground. Those pieces of spent satellites, rocket boosters  and the like, whip around the planet at about 17,500 mph, and those in a low orbit eventually re-enter the atmosphere.

The fence has tracked objects through the Cold War, NASA’s moon missions in the late-1960s and early ’70s, the Skylab space station, 30 years of Space Shuttle flights, which ended  this year, and the International Space Station.

The fence keeps track of  launches, maneuvers and re-entries, and its sensors can look for specific objects. In this case, it’s pretty easy to spot, about the size of a school bus and weighing in at 13,000 pounds. UARS  was launched in 1991, according to its website.  Decommissioned in 2005, it has been slowly losing altitude. NASA now says it will hurtle to Earth tomorrow afternoon, and that it won’t be passing over the U.S. during re-entry, though the impact area is still unclear.  The satellite is big enough that some of its  larger pieces will survive the fiery re-entry. The chances of it hitting  one of the world’s roughly 7 billion inhabitants is said to be about 1 in 3,200. The odds  of debris  hitting a specific person:  astronomical. Get NASA updates on the satellite  here.

The scenario might be something like that of Skylab in 1979. Skylab brings back some memories for me. I wrote a story that appeared in the Free Lance-Star on July 12, 1979–the day after the space station tumbled out of orbit, splashing down harmlessly in the Indian Ocean, and in desolate Western Australia. Back then, the space fence at Dahlgren was called the Naval Space Surveillance System.

 Here’s some of what I wrote : “As the final minutes came and went yesterday, scientists and mathematicians tracking the wayward craft at the Naval Space Surveillance System in King George were breathing a sigh of relief. The North American Air Defense Command, which is tied into the King George satellite tracking system, reports the the event was detected by a lonely tracking station off the West African coast and witnessed by thousands of  Australians.”

“Our predictions here are pretty much what NORAD has been saying all along,” NAVSPASUR Commanding Officer Capt. Thomas Adams said yesterday when reports of Skylab’s demise came at approximately 12:30 p.m.” 

Adams went on: “We  picked up Skylab on our sensors at San Diego and Elephant Butte around 8:35 a.m.” It was  to be the last time the spaceship–home to three crews of American astronauts–would pass over their sensors in the United States.

Permalink: http://news.fredericksburg.com/waterearthsky/2011/09/22/dahlgren-keeping-an-eye-on-dead-satellite/