Underpinning tributes this week marking the 25th anniversary of the Hubble Space Telescope's launch is the knowledge that the orbiting observatory has years of cutting edge science projects ahead.
The telescope blasted off aboard the space shuttle Discovery on April 24, 1990, fulfilling a dream dating back to the 1940s to put an astronomical observatory above the blurring and radiation-blocking effects of Earth's atmosphere.
Initially, it appeared that Hubble's mission was over before it began. Shortly after reaching orbit, engineers discovered the telescope's 94-inch primary mirror had a manufacturing flaw that blurred its vision.
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In 1993, NASA launched an unprecedented in-space servicing mission to outfit Hubble with corrective optics. Soon after, Hubble astounded astronomers by catching images of a comet plowing into Jupiter.
Over the next 15 years, astronauts made four more house calls to Hubble, installing new cameras and instruments, upgrading electronics, replacing computers. The repair and servicing missions led to a scientific bounty that has far exceeded Hubble's original goals: measuring how fast the universe is expanding; figuring out how galaxies evolve; and studying the gas that lies between galaxies, astrophysicist Mario Livio, with the Space Telescope Science Institute, noted in an essay in Nature.