Hubble Space Telescope - Lights go out for the old
man in space
The crown jewel of modern astronomy, the Hubble Space
Telescope nears its graveyard. The Columbia shuttle disaster
spelt the end of Hubble service missions, which are badly
required to keep the Hubble ship-shape. With Nasa throwing up
its hands, it is the end of days for the Hubble Space
Telescope.
13 Feb 2005
BY JM
Hubble space telescope: History
Over hundred years back, American
astronomers started building gigantic reflecting telescopes.
Astronomer Edwin Hubble built one of the biggest of them all,
measuring 100 inches in mirror diameter. His Mount Wilson
reflector telescope made one of the biggest discoveries in
astronomy of all time.
Edwin Hubble looked at distant
galaxies with his humungous telescope and observed that the
galaxies were constantly moving away from each other, that the
Universe was expanding. This effect was called the Hubble's
Law. Hubble's Law gave rise to the Big bang theory, which says
that the Universe was created out of an explosion of
compressed matter, which threw matter in all directions, which
became galaxies, stars and planetary systems. All forms of
matter, including life itself, owe their origin to this
explosion at the start of time.
This gave rise to the question of time
itself. How old is the Universe? To answer that question,
astronomers required more accurate, deeper-looking telescopes.
Larger telescopes like the Mount Palomar 200-inch reflector
telescopes were built. But it soon became clear to everyone
that more was required. Telescopes placed on Earth had to
encounter several atmospheric obstacles before taking in the
view of distant galaxies.
The new telescope needed to have a
clear view of space without the cloudy atmosphere in between.
In other words, a telescope located in space was the need of
the hour. Though a telescope in space was always a fancy
thought for stargazers, it was the dawn of rocket science and
the technological evolution that actually made the scientific
community give serious thought to a telescope in space.
The birth of Hubble Space Telescope
|
HUBBLE
SPACE TELESCOPE PROJECT HISTORY |
| 1977 |
Hubble telescope project
begins |
| 1985 |
Hubble space telescope built |
| 1990, 24 April |
Hubble space telescope
launched |
| 1990, 18 May |
First light |
| 1993, December |
space telescope flaw repaired |
| 2000, 24 April |
10 years of Hubble space
telescope |
| 2003 |
Columbia space shuttle crash;
All space shuttle flights cancelled |
| 2004 |
Last service mission to Hubble
called off |
| 2004 |
Proposal for robotic mission
falls through |
| 2007-08 |
Last light? |
Ideas about a space telescope took
birth in the 1920s. In the 50s and 60s, plans and sketches
were circulated, but nothing concrete could be drawn up.
Finally, in the 1970s, the project got underway in the United
States. Almost every astronomer worth his binocular gushed
about the promise of the new telescope.
The defining moment came with the
birth of the space shuttle, which could take the telescope to
space and deploy it there. Nasa developed the Hubble Space
Telescope and the shuttle to deploy it. Built at a cost of
$2billion, the Hubble Space Telescope was much smaller than
many of the gigantic telescopes previously built. It had only
a 96-inch reflector to take in the view. But that was more
than made good by its premium location in space. Hubble is
13.2 meters (43.5 ft.) long and its maximum diameter is 4.2
meters (14 ft.) It is about the size of a large
tractor-trailer truck. For some time, the Hubble Space
Telescope launch was delayed because of the Space shuttle
Challenger disaster.
The preparations finally drew to a
close and the astronomers held their breath as the space
shuttle lifted off to space. On April 24, 1990, the Hubble
Space Telescope was deployed in space. With Hubble, Nasa
opened a new window to the Universe. The Hubble Space
Telescope entered the orbit. Everything seemed to be going
fine. The thermal system, electronics, stabilisers, telemetry
and solar panels of the Hubble Space Telescope worked
perfectly well. But...
The Hubble Space Telescope
technical error
Hubble started beaming to Earth the
magnificent view it had of the Universe. Almost as an
anti-climax, the Hubble Space Telescope displayed a huge
technical error which went completely unnoticed during its
making on the ground. The main reflector of the Hubble Space
Telescope had a serious defect -- it was flatter than it
should have been. Instead of the accurate view astronomers
were dreaming about, Hubble Space Telescope showed a blurred
picture. The so-called "first-light", on 20 May was a complete
disaster. Initially, the technical team on the ground thought
it could have been a problem with adjusting the telescope
properly. But that was not to be.
It came to light that that the central
region of the mirror of the Hubble Space Telescope had a
curvature error -- by just one-fiftieth of the width of a
human hair. This is equivalent to only four wavelengths of
visible light, but it was enough. One insider said that the
Hubble mirror was "very accurate, very accurately the wrong
shape".
There seemed to be no hope for the
ill-fated mirror of the Hubble Space Telescope. Many years
before, when the mirror for the Hubble Space Telescope was
being made, a speck of paint had affected an optical measuring
rod. The subsequent measurements were very slightly wrong. Did
two billion dollars and all the dreams it spawned go down the
drain?
In Nasa’s technical language, the
Hubble technical error was said to be a "failure to meet a
level-one requirement". Translated to English, it meant a
complete catastrophe. For astronomers, this was the equivalent
of the Challenger disaster. Soon, the daily Hubble status
reports stopped.
The Hubble Space Telescope repair
But all hope was not lost. The Hubble
Space Telescope was a unique invention. It was designed to be
serviced and improved by astronauts while in orbit. The repair
of Hubble Space Telescope in space was one of the landmarks of
manned spaceflight. A series of corrective mirrors were fixed
to Hubble in five spacewalks on a single shuttle flight.
A few weeks after the surgery, Hubble
again turned its gaze towards the stars and beamed the most
amazing sights of the stars and galaxies that humans had ever
seen. They were sharp and crisp, just what astronomers had in
their dreams. Decades after it was first conceptualised, the
promise of Hubble Space Telescope was finally fulfilled. Now,
the Hubble Space Telescope (HST) had a clear and unhindered
view of the cosmos and it was not long before its images were
startling astronomers. Hubble's sharp, all-seeing eye observed
dust storms on Mars, birth of stars, galaxies and black holes.
Hubble's advantage lay in the fact
that it worked in the optical part of the spectrum and was
able to see fine details. It also has a wide and stable field
of view. It could resolve galaxies 13bn light years away, at
the edge of space and time.
In 1994, the Hubble Space Telescope
observed the broken remains of Comet Shoemaker-Levy 9 hitting
Jupiter. The pictures of a dark blemish spreading over
Jupiter's gaseous surface were unique.
Another spectacular observation made
by the Hubble Space Telescope was of the giant galaxy-cluster
named Abell 2218. Its heavy gravity distorts light from more
distant objects. This "gravitational lens" effect creates
spectacular arcs of smeared light. Studying them yields
important clues about the size and evolution of the Universe.
Even an ordinary person could make out the tremendous gravity
of Abel pulling light towards it. It was gravity at work, in
distant space, courtesy Hubble.
Again, the Eagle Nebula was spotted by
the Hubble Space Telescope. It is a huge cloud of gas and
dust, in which stars are formed. The Hubble noticed three
columns of gas containing bright points, each of which was
larger than our own Solar System.
Another observation, the Deep Field,
has been called a "bore-hole" through the cosmos. Hubble set
its sights on a blank patch of space for hours continuously,
to peer to the very edge of the Universe. The images captured
have become one of the scientific icons of our time. It shows
thousands of young galaxies. It is a glimpse of the dawn of
the Universe.
The Hubble Space Telescope also
noticed and relayed the births and deaths of stars and several
stellar effects. The Supernova 1987a explosion was picked up
by Hubble Space Telescope, the first such cosmic event since
the invention of the telescope.
The raison d'etre of Hubble Space
Telescope still remained. i.e., to find out of the age of the
Universe. How could it do it?
Hubble tried to do this by watching
Cepheids, which are stars which vary their light output,
depending on their absolute brightness. Hubble Space Telescope
used Cepheids to measure distances. Hubble measured Cepheid
variable stars 10 times further away than was possible before
and now about 30 galaxies have had their Cepheid distances
measured.
Nestled in its orbital slot, the
Hubble Space Telescope has contributed to our knowledge of the
age and evolution of the Universe. Now, whenever an object is
discovered using another kind of telescope, astronomers turn
to Hubble to see what it looks like. It has become astronomy's
default tool.
Hubble's data archive is the best-organised
of any observatory. Anyone can download all Hubble's images
just one year after they are taken. In the initial first year,
Hubble's observations belong to the astronomer who carries
them out. After that they belong to everyone.
This has led to the emergence of a
wide community of amateur stargazers and astronomers, who can
easily access the wealth of data beamed down by the Hubble's
advantage. They do not need to apply for telescope time, but
can use Hubble's archived data. With this, people with
internet across the world can do mainstream astronomy
research, despite never contributing to the cost of Hubble.
Hubble Space Telescope hits a rough
patch
Just as the Challenger disaster
delayed its voyage to space, the Columbia disaster practically
pulled the plug on the Hubble Space Telescope. In 2003, the
Columbia space shuttle exploded on its re-entry to atmosphere,
killing all aboard. Nasa immediately grounded the entire space
shuttle fleet, till better safety standards could be put in
place for astronauts. A Columbia Accident Investigation
Committee (CAIB) was set up, which probed the disaster and
make recommendations to avoid its recurrence.
Hubble took the beating. The Hubble
Space Telescope was designed to be periodically serviced by
astronauts, who would replace worn-out equipment and perform
maintenance at scheduled intervals. The last time astronauts
made it to the Hubble Space Telescope was in 2002. Hubble has
not seen a human visitor after that.
In the meantime, Hubble has been
functioning with all the wear and tear. Its gyroscopes, which
need replacement, are straining. Out of the six Hubble
gyroscopes, only three are working now. Gyroscopes are
required to properly position the Hubble Space Telescope in
its orbital watchtower. The batteries of the Hubble Space
Telescope also need replacement.
But the Columbia tragedy spelt the end
for Hubble. The CAIB recommended that space shuttle flights be
abandoned till further safety standards are put in place.
Hubble, in otter words, was to die a natural death.
The innumerable fans of the Hubble
Space Telescope were up in arms. Almost overnight, there were
petitions and a website came up to support Hubble,
www.savethehubble.com. It was established by University of
Brasilia lecturer Fernando Ribeiro following the US space
agency's decision to abandon the scope. "I hope it will become
a forum about Hubble's prospects and a launch pad (so to
speak) for a campaign to save it," he says.
But little could be done to save the
Hubble Space Telescope. In July last, Nasa administrator Sean
O'Keefe enthusiastically invited proposals to have robotic
servicing of Hubble. Several proposals were received from
several sources, but none could guaratee the precision of the
human hand. Especially in the backdrop of the huge costs
involved, the accuracy and success of a robotic service fell
far short of standards. After agonising it for a while,
finally Nasa abandoned the plan. With the last of the
scheduled service flights cancelled, the Hubble Space
Telescope prepares to die its slow death in space.
Nasa has taken enormous fire over its
decision to abandon the most-valued astronomical tool of all
time. But Sean O'Keefe says that NASA's priorities are to meet
President Bush's call for exploration of the Moon and Mars. He
says Nasa had to meet obligations to finish construction of
the international space station and launch a space shuttle
this year.
NASA will continue financing Hubble
operations until the probe's expected failure sometime after
2007. Nasa is planning to bring the telescope out of orbit and
dispose of it in the atmosphere by 2013. Nasa's total budget
rises 2.4% over 2005 to about $16.5bn (£9bn), but only $93m
would be spent on Hubble.
Nasa says that its decision to abandon
Hubble was out of two reasons:
• The Columbia Accident Investigation
Board's safety requirements for shuttle flights rule out
Hubble repairs by astronauts. The board was formed after seven
astronauts died in the 2003 explosion of the shuttle Columbia.
• A National Research Council panel
last year maintained that a 2007 robot repair mission was
technologically too risky.
Hubble Space Telescope: End of days
Nasa is again reviewing a Hubble Space
Telescope robotic rescue plan next month. But hope has already
died that Hubble will ever be back to its glory days. By
removing money from Nasa's budget for a robotic rescue, Nasa
has effectively driven the nail down the coffin of the Hubble
Space Telescope.
The US House Science Committee plans a
hearing on NASA's budget and Hubble later this month. But Nasa
has other plans for the space, which do not include the Hubble
Space Telescope. A second science mission, the 2015 Jupiter
Icy Moons Orbiter, is not financed yet. NASA says the nuclear
reactor needed for the mission was too advanced a technology
to pull off by 2015.
Hubble supporters still cherish the
hope that US Congress, which has to approve the budget, will
insist on money being found to save the orbiting observatory.
Meanwhile, techniques in Earth-based
astronomy have advanced, and British astronomers now use a
telescope in Hawaii twice as powerful as Hubble. But Hubble
and the dreams that it spawned are irreplaceable. With Nasa
abandoning its hopes, it's the end of days for Hubble Space
Telescope, our watchman in space.
BY JM
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