GigaOm has a great DIY project for space fans:
Signals picked up by the antenna, which is made of a 10-foot wooden board and metal coat hangers, are converted into tones that differ depending on the direction and location of an object. The tones, layered over a background of heavy static, grown louder and then softer as the object passes by, like a train traveling toward you and then barreling away.
Just hearing a tone doesn’t immediately give away the identity of an object. [Ham radio enthusiast Mike] Coletta refers to websites that track the location of space objects to be aware of what will be passing over at a determined time. If a tone occurs when a known object is overhead, he can make an educated guess at what he is hearing.
Coletta’s greatest ally for tracking space objects is the space fence, an Air Force-operated stretch of metal lattice in the southern U.S. that beams radio waves into space. If any object passes over the long, thin region of radio waves, it reflects some back to Earth. The Air Force has dedicated receivers to track the reflections, but hobbyists like Coletta can pick them up too. He estimates there are 100 to 150 other hobbyists in the U.S. monitoring for space fence signals.
Of course, there’s more than just fun behind this hobby…
Unfortunately for Coletta, the space fence will shut down October 1 to save the government $14 million a year. Additional Air Force radar systems will take over surveilling space until a planned superior space fence is completed. Unlike the space fences, the temporary radars in use won’t be tracking objects 24/7.
Instead, Coletta and people like him will be using Mexican TV (which is also bounced off satellites) to track the potential killer asteroids heading RIGHT FOR US. And, you know, whatever else is up there.