Several telescopes are operating in space right now. They scan
the heavens around the clock, in almost every wavelength of
energy. They produce spectacular pictures, and help astronomers
solve many mysteries, while discovering new mysteries for them
to ponder. The first satellite designed to study the universe
beyond our own solar system was launched 50 years ago today. It
was designed to study gamma rays, the most powerful form of
energy. Earth's atmosphere absorbs them, so at the time, the
gamma-ray sky was a complete mystery. Explorer 11 weighed just
82 pounds, and its single detector could provide only a rough
idea of the direction and timing of a gamma-ray observation. Its
tape recorder failed at launch, so most of its observations were
lost. And it was placed in a higher-than-planned orbit, which
carried it into the radiation belts that surround Earth. Even
so, Explorer 11 made some of the first observations of the
gamma-ray sky. Perhaps most important, it found no evidence to
support the Steady State t