The Hubble Space Telescope, once the butt of late-night talk-show jokes because of its flawed main mirror, is marking its 10th anniversary in space. And astronomers seem to be getting the last laugh.
"Not since Galileo aimed a small, 30-power telescope into the night sky in 1609 has humanity's vision of the universe been so revolutionized in such a short time span by a single instrument," said David Leckrone, Hubble project scientist at the Goddard Space Flight Center in Greenbelt.
Thanks to repairs and upgrades by three teams of spacewalking astronauts, and long photo exposures outside the distortions of the atmosphere, Hubble's first decade has produced a flood of discoveries.
Its razor-sharp images and spectrographs, spanning infrared, visible and ultraviolet wavelengths, have abruptly resolved old questions and opened volumes of new debates for astronomers and cosmologists to tackle.
Hubble's measurements of the faintest and most distant stellar explosions called supernovae have helped confirm evidence from other observatories that the expansion of the universe is accelerating, a new mystery that has scientists baffled.
The space telescope's ability to resolve the shapes of distant galaxies has helped to prove that enigmatic gamma ray bursts -- the most powerful blasts in the universe -- came from remote galaxies at a distant time when stars were forming at very high rates. The question now is why.
By carefully measuring distances to two peculiar classes of stars that only Hubble can isolate amid the swarms of stars in distant galaxies, two teams of Hubble scientists have dramatically narrowed debate about the age of the universe, the rate at which it is expanding, and its ultimate fate.
Hubble has given astronomers their sharpest views yet of the shapes of galaxies and exploding stars. That has advanced their theories, and sharpened their questions, about the evolution of galaxies since the Big Bang, and the physical processes that drive the birth and death of stars.
"Hubble has allowed us to see things, the type of detail, that no other telescope allowed us to see," said Mario Livio, science chief at the Space Telescope Science Institute in Baltimore. "It has brought these spectacular images into homes around the globe."
Hubble's beautiful photos -- an expanding gallery of pictures of serene planets, colliding galaxies, exploding stars and towering stellar nurseries -- turn up everywhere, as posters, on the covers of books unrelated to Hubble, and as backdrops in space movies.
Two decades of work
Hubble was carried into orbit by the shuttle Discovery on April 24, 1990, after two decades of planning, construction and launch delays. Since then, it has circled the planet more than 58,400 times, putting more than 1.5 billion miles on its odometer.
The 12-ton, bus-sized telescope has made more than 273,000 observations and looked at about 14,000 objects. It gathers enough scientific data every day to fill a typical desktop home computer -- a total of more than 3 1/2 trillion bytes.
But it did not get off to a good start. The telescope's main mirror -- ground to the wrong prescription -- was an acute embarrassment to NASA, and an agony for the astronomers and engineers who had dedicated much of their careers to Hubble.
It was more than three years before astronauts carrying an ingenious package of corrective optics arrived in orbit to fix the problem. They saved the $3 billion program from disaster and silenced the comedians.
In two visits to the observatory since then, astronauts carrying long to-do lists have replaced a host of failed or obsolete hardware, including the cranky gyroscopes that shuttered the observatory last fall.
Better still, they have exchanged much of Hubble's original scientific equipment for new, state-of-the-art instruments.
"It's been a real roller-coaster, but we're really having a good time now. It's better than new," said Preston Burch, Hubble operations "We expect to keep Hubble on the forefront of discovery."
Preston Burch,Hubble operations manager at Goddard
manager at Goddard.
Well, sort of. The telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has been idled since December 1998 when its vital coolant warmed up prematurely. It's scheduled for repairs during the next servicing mission, in June 2001.
And like any 10-year-old vehicle, Hubble has some dings. An antenna has a quarter-sized hole in it, punched by a speeding meteoroid.
In fact, astronaut John Grunsfeld said, "the telescope is riddled with tiny holes" -- as many as 30 or 40 in every 15 square inches of its silvery insulation.
But the celestial buckshot hasn't affected Hubble's operations. And the astronomers who use it still regard the telescope and anyone who has touched it with awe. Grunsfeld and crewmate Claude Nicolier -- both members of the 1999 repair team -- got a standing ovation and shouts of "Bravo!" from astronomers who gathered recently in Baltimore to review Hubble's achievements.
The spacewalkers' efforts saved the livelihoods of many in the room. And with luck, they ensured that Hubble could continue its observations, perhaps for years.
NASA originally pegged Hubble's life expectancy at 15 years. But the three servicing missions since then -- and the expectations for at least two more, in 2001 and 2003 -- have extended its useful life by five years, until 2010.
After three new instruments are installed on those missions, the cascade of data from Hubble will grow 44 times larger.
"The rate of scientific discovery is directly related to the amount of information we bring back," Burch said. "So we expect to keep Hubble on the forefront of discovery."
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