The Best Telescope
for astronomers seeking pin sharp views of the depths of the Universe is the Hubble
Space Telescope. Launched in 1990 after decades of planning, Hubble is an unmanned
observatory in orbit far above the clouds and atmospheric dust that block the view of
Earth based telescopes. Astronomers from dozens of countries use Hubble ,
functioning it by remote control. The human observer at the light detectors, while
electronic cameras document excellent images of the cosmos.
heart of Hubble is a reflecting telescope much like telescopes on Earth. In space,
however, it must operate without mains electricity , a mounting to swivel it around, or
cables linking it to control computers. Instead , Hubble carries the type of equipment
found on many satellites: solar panels to provide power, reaction wheels for pointing, and
radio antennas for communicating with Earth.
control for Hubble is at NASAs Gordard Space Flight Center, in Maryland, USA. All
signals to and from Hubble pass through this center, where engineers constantly monitor
the spacecrafts health. The engineers act as a link between the orbiting telescope
and the Hubble astronomers, working at the nearby Space Telescope Science Institute in
Baltimore, who control the telescopes observing schedule.
The first pictures
astronomers received from Hubble were out of focus, though still better than any
ground-based telescope. NASA realized that the mirror had been made in slightly the wrong
shape, 0.002 mm too shallow at the outer edge.
firmly in the grip of Space Shuttle Discovery, astronauts Steven Smith and Mark Lee
service the orbiting telescope. Like any other vehicle, Hubble needs regular servicing.
Shuttle astronauts replace equipment such as computers and tape recorders and update the
telescope by installing new cameras and detectors for light and infrared radiation. On the
first servicing mission in 1993, they installed"contact lenses"to correct the
focus because of a fault on the main mirror that blurred Hubbles view.
ADVANTAGES OF HUBBLE
viewing the Universe from Earth must look upwards through our turbulent atmosphere, which
constantly shifts and distorts the light from stars and galaxies rather like
looking through the swirling water in a busy swimming pool. Thats why stars seem to
twinkle. From its perch above the atmosphere, Hubble has a clear view of everything in the
Universe, from planets to quasars billions of light years away.
||25 April 1990
||12.1 x 2.4 m
|Height of orbit
|Period of orbit
||15 years (may be extended )
|Cost (at launch )
|American astronomer Lyman Spitzer (1914- )
first proposed an extraterrestrial observatory in 1946.
|In 1977, NASA begin to build Hubble.
|The Space Shuttle launched Hubble in 1990.
Astronomers soon found the main mirror was slightly the wrong shape, but computers could
help compensate for the fault.
|In 1992, Hubble found evidence for a
massive black hole in the galaxy M87.
|Servicing mission in 1993 corrected
|In 1994, Hubble recorded Comet
Shoemaker-Levy 9s impact with Jupiter.
|In 1995, Hubble photographed starbirth in
the Eagle Nebula. Hubble also produced a view of the most distant galaxies, up to 10
billion light years away.
|An infrared camera was added to Hubble in
1997. Later it checked landing sites for Mars Pathfinder and monitored dust storms on
|In 1999, Hubble detected the galaxy
containing an energetic gamma-ray burster the most powerful explosion ever