Spy satellites could soon be equipped with artificial "eyelids" to prevent them being blinded by enemy lasers.
Military satellites have extremely sensitive cameras to spy on the movements of troops and vehicles on the ground. But a bright flash of powerful laser light could damage the cameras' optical sensors, so the military is keen to find ways of protecting them.
"Basically, you don't want to put a billion dollar satellite into orbit if someone can put it out of action with a laser the next day," says Gary McGuire of electronics company MCNC in North Carolina. So he and his colleagues have built a protective eyelid from arrays of electrodes (see right).
To make the eyelid, transparent electrodes made from indium-tin oxide are attached to a sheet of glass. Opaque electrodes are then attached to one edge of each transparent electrode. The polymer coating on the opaque electrodes is applied at 400 ¡C and shrinks as it cools, coiling back to an "open" position.
Applying opposite voltages to the top and bottom electrodes induces electrostatic attraction between them, pulling the opaque electrodes down and shutting the eyelid. Switch off the voltage and the top electrodes spring back open. In tests, the eyelid could open and close four thousand times a second.
But Norm Barnes of NASA's Langley Research Center in Virginia says that the eyelid will have to shut much faster than that to protect satellites from lasers. "The response time of the protection system should be sub-nanosecond," he says.
Author: Ian Sample
New Scientist issue: 18th March 2000
PLEASE MENTION NEW SCIENTIST AS THE SOURCE OF THIS STORY AND, IF PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO: http://www.newscientist.com