Spaceballs

Building a telescope like you've never seen.

by Illustration by: Ben Simons/Sydney Vislab
An array of Luneberg lenses, as seen in this illustration, could become part of a telescope bigger than any now in existence.Illustration by: Ben Simons/Sydney Vislab

"Think about your eyeball," urges Peter Hall. It, your brain, and your retina "allow you to build an image in an instant using parallel processing. That's what a Luneberg lens could do for astronomy."

Conceived by R.K. Luneberg at Brown University in 1944, the lens is spherical and symmetrical and, therefore, very effective at multibeaming, or handling many sources simultaneously, much as an eyeball does. "A traditional dish antenna looks in only one direction at a time," says Hall. "But by populating a Luneberg lens' focal surface with feed antennas, we can make a radio 'retina.'"
Hall and his Australian colleagues are testing the lens for use in a huge radio-wave telescope hundreds of times larger than any in operation today. The project, to be built in 2010 by an 11-nation consortium, will be called the Square Kilometre Array. Plans call for tens of thousands of Luneberg lenses to be grouped in arrays at hundreds of different locations. This large collecting area would be able to peer far enough into space to receive "whispers" from the first billion years of the universe's existence.

That's the hope, anyway -- if the Australians can figure out how to make Lunebergs of lighter, cheaper materials that retain more radio signal.