Space Telescopes

Space scientists began to send instruments into orbit on satellites in the 1960s when the Space Age got its stride. Astronomers were not slow to take advantage of this new technology. On Earth the dust, moisture and air currents in the atmosphere distort their vision of the Universe. Sending telescopes, detectors, and other instruments into space enabled them to view the Universe more clearly. They were also enable to view gamma ray, X-ray, ultraviolet and infrared. The study of X-rays and gamma rays from the heavens began in the 1960s with instruments carried into the high atmosphere by rockets. They found evidence of the presence of those awesome bodies we know as black holes that gobble everything nearby, even light. They also found bursters, which caused bursts of gamma rays from the heavens that lasted a fraction of a second but packed the power of 100,000 Suns.

Two satellites called International Ultraviolet Explorer (IUE) and Infrared Astronomy Satellite (IRAS) have revolutionized the exploration of the visible spectrum, the ultraviolet and infrared.

(above) IRAS, the infrared astronomy satellite. To make it sensitive to incoming infrared rays, the detector was cooled by liquid helium to -269° C.

In April 1990 the Hubble Space Telescope (HST) was launched into orbit to pioneer optical astronomy from space. It had been designed over a period of twenty years, and will cost $8 billion. It will be effective in space for just fifteen years.

The telescope is designed to see further and more clearly into the depths of space than ever before. The telescope can be used to send its images to one of several detecting instruments in turn. The most spectacular results will probably come from the 'wide-field' camera. This can take large, clear pictures of large objects like nearby galaxies and planets. Most of its time is spent pin-pointing the areas near black holes and measuring the effect of gravity on starlight.

It will get its advantages by being outside the Earth's atmosphere. Earthbound telescopes have to look through many kilometers of air. This air makes stars 'twinkle' - which means that their images dance about and aren't clear. Using bigger telescopes just means getting a bigger blur. Also, some radiations are absorbed by the atmosphere, and so never reach the Earth's surface.

Amazingly, once on orbit, its light-gathering mirrors were found to be defective and the hoped for quantum leap in optical performance over Earth-based telescopes has not happened. Its faulty mirror and solar panels were repaired in 1994 in a successful spacewalk from Space Shuttle.

(above) The Hubble Space Telescope.

(above) A HST image showing the ring around the supernova star.

See here for more information about the Hubble Space Telescope