The Hubble Space Telescope was launched 1990 with the Space Shuttle Discovery and is one of the most important telescopes in the history of astronomy. But the future is uncertain, because the NASA will no further maintenance mission realise and without intervention it will re-enter the Earth's atmosphere some time after 2010.

Repair

In December 1993 the first repair already followed, since the primary mirror exhibited an error and the Hubble therefore got now "eyeglasses”. This repair was accomplished with space walks of astronauts at the mission STS-61, which was carried with the Space Shuttle Endeavour into the orbit.

Spacecraft

Four antennae send and receive information between the telescope and the Flight Operations Team at the Space Telescope Science Institute.

Flanking the telescope's tube are two thin, blue solar arrays. Each wing-like array has a solar cell "blanket" that converts the Sun's energy into 2,800 watts of electricity.

Some of the energy generated is stored in onboard batteries so the telescope can operate while it's in Earth's shadow (which is about 36 minutes out of each 97-minute orbit). Fully charged, each battery contains enough energy to sustain the telescope in normal science operations mode for 7.5 hours, or five orbits.

Designers of the Hubble Space Telescope had to take into account the conditions in which it was to operate. Hubble would be subject to the rigors of zero gravity and temperature extremes — fluctuations of more than 100 degrees Fahrenheit during each trip around Earth. To accommodate this less-than-hospitable operating environment, Hubble was given a "skin," or blanket, of multilayered insulation (MLI), which protects the telescope from temperature extremes. Beneath the MLI is a lightweight aluminum shell, which provides an external structure to the spacecraft and houses its optical system and science instruments.

Hubble's optical system is held together by a truss (supporting "skeleton") measuring 5.3 m in length and 2.9 m in diameter. The 114 kg truss is made of graphite epoxy — the same material used in many golf clubs, tennis racquets, and bicycles. Graphite epoxy is a stiff, strong, and lightweight material that resists expanding and contracting in extremes of temperature.

Optics

Hubble's "eyes" are actually a system called the Optical Telescope Assembly. That system consists of two mirrors, support trusses, and the apertures (openings) of the instruments.

Technics

Taking color pictures with the Hubble Space Telescope is much more complex than taking color pictures with a traditional camera. For one thing, Hubble doesn't use color film — in fact, it doesn't use film at all. Rather, its cameras record light from the universe with special electronic detectors. These detectors produce images of the cosmos not in color, but in shades of black and white.

Finished color images are actually combinations of two or more black-and-white exposures to which color has been added during image processing.

The colors in Hubble images, which are assigned for various reasons, aren't always what we'd see if we were able to visit the imaged objects in a spacecraft. We often use color as a tool, whether it is to enhance an object's detail or to visualize what ordinarily could never be seen by the human eye.

Astronomical pictures from Hubble often look different to naked human eyes

Light from astronomical objects comes in a wide range of colors, each corresponding to a particular kind of electromagnetic wave. Hubble can detect all the visible wavelengths of light plus many more that are invisible to human eyes, such as ultraviolet and infrared light. Astronomical objects often look different in these different wavelengths of light. To record what an object looks like at a certain wavelength, Hubble uses special filters that allow only a certain range of light wavelengths through. Once the unwanted light has been filtered out, the remaining light is recorded.

Many full-color Hubble images are combinations of three separate exposures — one each taken in red, green, and blue light. When mixed together, these three colors of light can simulate almost any color of light that is visible to human eyes.

Instruments

The Hubble Space Telescope's five science instruments: