HUBBLE emerges from the shuttle cargo bay during its launch in 1990.
The idea of an orbiting observatory flying above the distorting atmosphere was conceived in the 1940s and actual planning began in 1979. But the concept didn't become a reality until the Hubble Space Telescope was placed in orbit by a space shuttle crew in 1990. Roughly cylindrical in shape, it is 13.1 meters long and 4.3 meters around at its widest point.

Although it was the first orbiting observatory, the Hubble got off to an unsteady start. The primary mirror of its 2.4 meter telescope was hopelessly flawed. Fortunately, the observatory's designers had planned on servicing the telescope in space and had equipped it with numerous handholds and grapple fixtures so it could be recovered for maintenance. In 1993, astronauts visited the ailing telescope and installed optics that corrected the abberant mirror.

Forming stars
STELLAR SNAPSHOT. Among the spectatacular images made by the Hubble since the repair of its flawed mirror is this picture of embryonic stars forming in a dark cloud of dust in the Eagle nebula.

The results were nothing short of spectacular. With its 0.1 arc second resolution--10 times better than most ground-based telescopes--the repaired Hubble could peer deeper into space and further back in time than any instrument that preceded it. It soon began sending back startling images of colliding galaxies, swirling clouds of interstellar gas, stars being born and dying and planets forming around distant suns. And it turned its eye as well to the planets and other objects in our own solar system, snapping pictures of giant cyclones on Mars and huge spring storms on Uranus. It's measurements of the rate at which the universe is expanding have provided clues to universe's ultimate fate.

Hubble's complement of instruments, which includes three cameras and two spectrographs, make it capable of performing observations in the visible, near-ultraviolet and near-infrared. It's spectrographs permit astronomers to analyze the light from celestial objects and then determine such factors as their chemical composition, temperature, radial velocity, rotational velocity and magnetic fields. An image intensifier can amplify incoming light so that it is 100,000 times brighter, making it possible to observe very distant and very faint objects.

As it nears the end of its first decade in space, the Hubble has indisputably earned its place as the flagship of NASA's Great Observatories. It's namesake, Edwin Powell Hubble--the astronomer who first determined that there were other galaxies beyond our own and that the universe is expanding--would be proud.

Hubble schematic

Images: NASA
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