Only the visual and radio bands of the electromagnetic spectrum pass through Earth's atmosphere relatively unhindered. For everything else, gamma-ray. X-ray, ultraviolet, and infrared, observations of space are much better from above Earth's atmosphere.
The first real telescope in space was Orbiting Solar Observatory-1 (OSO-1), which was launched into a low Earth orbit on March 7, 1962, from Cape Canaveral. The lower portion rditated every two seconds, and the upper portion was fixed in space, using sun sensors and servomotors to point instruments accurately at the solar disc. The main aim was to observe solar flares—extremely violent explosions that occur near sunspots on the solar surface—in the gamma-ray, X- ray, and ultraviolet wavelengths. The spinning part of the spacecraft searched the whole sky for stellar gamma-ray sources. After three months and over 1,000 orbits the effectiveness of OSO-1 was greatly reduced when the United States tested a nuclear device at high altitude.
OSO-1 demonstrated that delicate instrumentation could be flown successfully for long periods of time on stabilized orbiting spacecraft. The National Aeronautics and Space Administration (NASA) went on to build a series of space observatories, including the Hubble Space Telescope (launched in 1990), the Compton Gamma-Ray Observatory (launched 1991), the Chandra X-ray Observatory (launched 1999), and the Space Infrared Telescope Facility now called the Spitzer Space Telescope (launched 2003). Space observatories either search the sky for sources or collect data from specific objects.
