SEARCHLIGHTS AND SATELLITES (73 K)

These Searchlights May Track Man's Elusive Moon
A small sphere at great height will be hard to see. It may be barely visible to the naked eye, but for only fleeting moments before dawn and after sunset. Sky brightness during the day will outshine the satellite's reflected light. At night, as the satellite passes through Earth's shadow, observation will be difficult even with telescopes. Scientists are considering an idea that may solve the viewing problem at night. Dr. John O'Keefe of the U. S. Army Map Service has suggested focusing batteries of powerful Army searchlights on the tiny object. If the sphere were equipped with retrodirective mirrors, the light would return to Earth along the line of the incoming beam, and the satellite would appear in telescopes near the searchlights as a moderately bright star. Army engineers, using four lights, here simulate satellite tracking at Fort Belvoir, Virginia. Each beam packs 800,000,000 candlepower. [ National Geographic Photographer B. Anthony Stewart ]