快猫短视频

SPY satellites could soon be equipped with artificial 鈥渆yelids鈥� 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鈥� optical sensors, so the military is keen to find ways
of protecting them.

鈥淏asically, you don鈥檛 want to put a billion dollar satellite into orbit if
someone can put it out of action with a laser the next day,鈥� 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 掳C and shrinks as it cools, coiling back to an 鈥渙pen鈥�
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鈥檚 Langley Research Center in Virginia says that the
eyelid will have to shut much faster than that to protect satellites from
lasers. 鈥淭he response time of the protection system should be sub-nanosecond,鈥�
he says.