After man
discovered that there is a world beyond the earth on which we live, a world of
moons, a world of other planets and various galaxies, man in holy curiosity
developed the thirst to get more information about other bodies outside the
earth.
The earth is
the most conducive planet for living with the presence of oxygen and gravity to
allow freedom of movement. Places beyond the livable atmosphere of the earth
are loosely called space.
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| Hubble Space Telescope. Image: Wikipedia |
Telescopes
have increased in size and image clarity over the years. The outer space has
been viewed with telescopes from the earth. However, the Achilles’ heel has
been the obstruction of view of the telescope by the atmosphere.
This led to
the thought that there would be a better view of the universe if a telescope
could be placed in space where there will be little to no obstruction to the
view of planets and their moons, galaxies and other bodies.
In 1946,
American astrophysics Lyman Spitzer Jr. wrote a paper proposing a space observatory.
He was one of the most important people that made the space telescope a reality
about 44 years later.
National
Aeronautics and Space Administration (NASA) in conjunction with the European
Space Agency (ESA) proposed the construction of a large space telescope (LST)
that will be sent to space for a better observation of the universe.
The LST was
later renamed Hubble Space Telescope (HST) in honour of Edwin P. Hubble. Edwin
Hubble was the first man to declare that the universe is getting bigger in size
and also calculated the rate.
Work began on
the HST which was to have a massive length of 13.2m. In comparison it is as
long as a big school bus (longer than a coaster). The mirror which was to be
used was constructed by Perkin-Elmer
Corporation.
The primary
mirror was to have a diameter of 2.4m and a weight of 828kg (1,825lb) while the
secondary mirror was to have a diameter of 0.3m and a weight of 12.3kg (27.4lb).
The initial plan was for a primary mirror of 3m in diameter but was reduced due
to cost.
The Hubble
Space Telescope receives light through the primary mirror. The light then
bounces off to the secondary mirror which in turn focuses the light on the
telescope’s science instruments. The HST is known as a Cassegrain reflector.
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| One of the most famous image by the HST, 'Pillar of Creation' showing developing stars in the Eagle Nebula. Image: NASA, ESA |
The Hubble
Space Telescope is being powered by solar panels and it consumes 2,800 watts of
electric power. Energy from the solar panels is stored on 6 nickel-hydrogen
(NiH) batteries which has a storage capacity equal to 20 car batteries. It has
a massive weight of 11,110kg (24,500lb).
The initial
planned cost of the HST was exceeded due to delay in the production of the
mirror by Perkin-Elmer. The HST was
scheduled to be launched into space by October 1986. It was however delayed due
to the explosion of Space Shuttle Challenger during a space flight earlier that
year. This led to the suspension of the space shuttle program for two years.
The Hubble
Space Telescope was finally launched into space on the 24th of April, 1990
through the space shuttle Discovery (STS-31). There had been high hopes that
the HST was going to solve many mysteries surrounding the universe that
telescopes on earth had been able to tackle with little success.
The cost of
the project at the time of the launch was $2.5bn but later increased to $10bn
(as of 2010) due to maintenance costs that followed in later years.
Disappointment
was the initial result that came from the HST as it sent blurred images back to
the earth. This was caused by an error (spherical aberration) of about 1/50th
of the thickness of a sheet of paper in the manufacture of the mirror.
A manned
space mission was sent to the space in 1993 to correct this mistake. It was
corrected by placing the Corrective Optics Space Telescope Axial Replacement
(COSTAR) in the telescope. Wide Field and Planetary Camera 2 (WFPC2) which
contained small mirrors was also installed in place of WFPC to correct the
aberration. Another space mission went in 1997 to replace and repair
instruments in the telescope.
The third
space mission went in 2000 and the fourth in 2002 while the last went in 2009.
Most missions were for repairs and replacement of faulty parts.
It is
expected that the HST will be de-orbited by 2016. The HST orbits the earth at a
distance of 569km from the surface of the earth. The HST orbits the earth at a
speed of 28,000km/h (17,500mph) which allows it to complete a single orbit of
the earth in 97 minutes.
The HST has
aided a lot of research into the activities in space. It is reported that many
research involving astronomy have used HST data in their research. Over 9,000
papers based on Hubble data has been published in peer reviewed journals, and
other appeared in conference proceedings.
The Hubble
Space Telescope sends a data of about 120GB to the earth every week for
analysis. The data is stored in magneto-optical disks. Selected number of
people are allowed to have access to the HST every year.
The HST has
been able to establish the fact that the universe is expanding. The HST has
also been able to determine the age of the universe to be between 13 to 14
billion years instead of the wide assumption of 10 to 20 billion years
initially accepted.
The HST was
also able to picture the collision of the comet Shoemaker-Levy with Jupiter in
1994. It discovered Nix and Hydra, two moons of Pluto. In 2006 (image released this
week), the HST spotted a cosmic caterpillar that’s 6 trillion miles long,
formed by harsh winds from some of the hottest stars.
The Hubble
Space Telescope is an amazing observatory that has given us more knowledge
about the space and has expanded the view that scientists like Galileo Galilei
had when they were alive.
The Hubble
Space Telescope will be replaced by James Webb Space Telescope (JWST) which
will have a primary mirror with a diameter of 6.5m. It is expected that the
JWST will be launched into space by 2018.
Credits:
Wikipedia, Hubblesite, Space
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The Hubble Space Telescope (HST) is amazing