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U.S. 'Space Fence' Will Cease To Operate, Site Says

A rendering of objects currently in Low Earth Orbit (not illustrated to scale). According to NASA, "approximately 95 percent of the objects in this illustration are orbital debris, i.e., not functional satellites."
A rendering of objects currently in Low Earth Orbit (not illustrated to scale). According to NASA, "approximately 95 percent of the objects in this illustration are orbital debris, i.e., not functional satellites."

A U.S. radar system that tracks thousands of objects orbiting Earth — from satellites to harmful debris — has been slated for shutdown, according to the Space News site. The ground-based network known as the "Space Fence" may cease to operate in October.

"This is your notice to begin preparing the sites for closure," a memo from Air Force Space Command told the contractor that operates the arrays last week. The memo obtained by Space News continues, "A specific list of action items will be provided as soon as it is finalized. A specific date to turn off the mission system has not been established yet, but will be provided to you immediately upon determination."

The pending shutdown is being blamed on the government's sequestration cuts and on the Strategic Choices and Management Review that the Pentagon is using to find areas of potential savings. Secretary of Defense Chuck Hagel ordered that broad review several months ago.

Efforts to award a contract to build an updated version of the Space Fence system, parts of which date from the 1960s, have been held up by budgetary concerns.

At a meeting with congressional lawmakers last month, Gen. William Shelton, commander of Air Force Space Command, said his division is ready to award the contract to build a new Space Fence, but it hasn't been able to make the decision official due to the review process.

"I can tell you from a personal perspective it's a high priority for Air Force Space Command, and I think for the nation in terms of space situational awareness," Shelton added. "So we're hopeful that we'll get authority to award that contract very shortly."

As Space News notes, the very high frequency (VHF) radar arrays that make up the Space Fence are only one part of a U.S. network that tracks objects in orbit.

But, the site adds, "It is responsible for approximately 40 percent of all observations performed by the Air Force-run Space Surveillance Network," citing the Secure World Foundation's technical adviser, Brian Weeden.

In case you're wondering just how much material is whizzing around the Earth, here's the most recent data we could find, from NASA:

"More than 21,000 orbital debris larger than 10 cm are known to exist. The estimated population of particles between 1 and 10 cm in diameter is approximately 500,000. The number of particles smaller than 1 cm exceeds 100 million."

Update at 4:20 p.m. ET: Space Station Concerns

Writing to us from Colorado, satellite watcher Mike Coletta, who runs the website SatWatch.org, reminds us that the International Space Station and other projects use data from tracking systems to avoid potential troubles.

"I do not think there is a system that can detect all objects orbiting over [the continental United States] and then determine an orbital path as the Space Fence does now," Coletta says. "It is a 24/7 system that gathers data without having to be tasked, something most other space radars don't do."

Coletta notes that the signals of the Space Fence are out there for all of us to hear — and many ham radio enthusiasts do just that. The three transmitters in the system, which are in Arizona, Texas and Alabama, operate at around 216.98 MHz.

If you'd like to hear a live audio feed, Space Weather Radio has it for you. Or for a "greatest hits" of one day of recordings, that's on YouTube.

Our original post continues:

Last spring, NASA came close "to losing its $500 million Fermi Gamma-ray Space Telescope in a narrowly averted collision with a defunct, Cold War-era Soviet spy satellite," as The Two-Way reported.

And in what may be one of the most fastidious reasons ever to aspire to a mission in orbit, Switzerland said in 2012 that it had begun a project with the goal of tidying up the junk-strewn space around our planet.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Bill Chappell is a writer and editor on the News Desk in the heart of NPR's newsroom in Washington, D.C.
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