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A brief history and the future of the Hubble Space
Telescope
The Hubble Space Telescope solves the problems caused
by viewing the universe through the turbulent blanket of air that surrounds
the earth. Hubble solves these problems by “living” in orbit
around the earth and outside that blanket of air. Before its launch, astronomers
had not been able able to take pictures of deep space with such clarity.
It took a long time, from the conception of the telescope
in 1948 to its realization and its current excellence. The launch on April
24, 1990 , put the telescope in an elliptical orbit above the earth. There
was great excitement when the first image were sent to earth, but it soon
became obvious that the main mirror had an error in its shape that was
blurring the images. A mission by the space shuttle, Discovery, added
an optical correction called “COSTAR” that brought the telescope
to full clarity.
The great cost and the technological challenge of developing
telescopes in space is being met by a joint effort between NASA and the
European Space Agency. Since that time, several other space telescopes
have been launched, each with it’s own, special capabilities. The
Hubble Space Telescope will be 17 years old in April of 2007. A space
telescope is like a cat in that both are “old” at the age
of 17. With age, the Hubble developed some serious problems, which now
greatly limit its use. When astronomers want to point the telescope at
an object of interest, the telescope is turned toward the object and held
there by gyroscopes. Some of those gyroscopes have died of old age. The
failure of another gyroscope will render the telescope useless. The main
camera has also failed.
The space telescope is above almost all the earth’s atmosphere,
but there are still enough molecules of air that the telescope slows down
just a tiny bit whenever it hits one. When an object orbiting the earth
slows down, it also moves a little closer to earth. As it moves closer
to the earth, the atmosphere becomes denser and the slowing force even
er. At the rate that the Hubble Space Telescope is descending into the
atmosphere, it will heat up from the friction of the air and burn up around
the year 2011.
The loss of the Hubble Space Telescope would be a great loss
indeed. A mission to rescue the HST is now planned for September 11, 2008.
It will require two space shuttles. The first, the Atlantis, will visit
the Space Telescope and push it, increasing its speed and the height of
its orbit. Astronauts will also repair the camera and the gyroscopes.
The second space shuttle, Discover will be ready for launch should the
astronauts need to be rescued on this difficult mission. It is hoped that
this mission will keep the Hubble functioning through 2013.
A new space telescope, the James Webb Space Telescope
(JWST), will be launched at about the time the Hubble goes out of service.
The JWST will not be able to take pictures in visible and ultraviolet
light like the Hubble, but it will be far superior in its ability to see
in the infrared part of the spectrum. |
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Mark Voit 