Space & Innovation

Hubble at 25: Brief History of the Hubble Space Telescope

It's been an eventful 25 years for what turned out to become the world's best-known telescope and perhaps among the most productive science instruments ever made. Here's a look at Hubble's life in pictures.

With the Hubble Space Telescope packed in its cargo bay, shuttle Discovery lifts off from Kennedy Space Center's Launch Pad 39A, while another shuttle, Columbia, is being prepared for launch on the Astro-1 mission. Columbia was later lost and its crew killed during NASA's second fatal shuttle accident in 2003. | NASA
With the Hubble Space Telescope packed in its cargo bay, shuttle Discovery lifts off from Kennedy Space Center's Launch Pad 39A, while another shuttle, Columbia, is being prepared for launch on the Astro-1 mission. Columbia was later lost and its crew killed during NASA's second fatal shuttle accident in 2003. | NASA

No matter how much longer the Hubble Space Telescope will last, its place in history is assured. As it begins its 25th year in orbit on Friday, Hubble already has proven to be among the most popular, productive and groundbreaking science instruments in history. But the story could have had quite a different ending. Here's a look at Hubble's checkered history.

Hubble at 25: Space Telescope's Top Science Discoveries

Delayed by technical problems, budget overruns and then the heart-breaking loss of the space shuttle Challenger, the Hubble Space Telescope finally rocketed into orbit aboard space shuttle Discovery on April 24, 1990. The project had taken to build and launch than any other spacecraft in NASA's history, including the Apollo moon rockets.

Technicians work on Hubble's glass primary mirror, later found to have a manufacturing defect. Light reflects off the main mirror and strikes a second, smaller mirror, then bounces back again through a 2-foot (0.6 m) diameter hole in the center of the main mirror so it can be captured by cameras and science instruments. In this picture, the hole covered. | NASA

Two months after Hubble finally reaches orbit, engineers and scientists discover that its primary 94 inch-diameter mirror is flawed, the result of a manufacturing problem that somehow escaped detection. Overnight, NASA's star project became comedy show fodder and with it NASA's reputation.

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Astronauts Story Musgrave, attached to the shuttle's robot arm, and Jeff Hoffman, in the payload bay, wrap on work on Hubble during the first servicing mission to Hubble in 1993. Over the next 15 years, NASA sent four more shuttle crews to upgrade and repair the telescope. | NASA

After three years of preparations, NASA mounts a rescue mission on Dec. 2, 1993, to install a new camera and corrective optics into the telescope. During five spacewalks -- a record at the time -- astronauts also attached upgraded solar arrays and other equipment.

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Hubble's view of the spiral galaxy M100 before and after astronauts installed corrective optics. | NASA/STScI/JPL

It was a tense Christmas break while engineers carefully checked out the refurbished Hubble observatory, hoping for the best, but fearing the worst. At a press conference in mid-January, program scientist Ed Weiler reported a success. "It's fixed beyond our wildest expectations," he said. Senator Barbara Mikulski, a Maryland Democrat who at the time chaired the Senate finance subcommittee overseeing NASA, famously declared, "The trouble with Hubble is over."

Hubble at 25: What's Next for the Space Telescope?

Hubble's first Deep Field image reveals distant galaxies nearly 4 billion times fainter than what the human eye can see. The image was assembled from hundreds of separate exposures taken during 10 consecutive days in December 1995. Bluer objects contain young stars and/or stars that are relatively close, while redder objects contain older stellar populations and/or are farther away. | R.Williams/STSci/Hubble Deep Field Team/NASA/ESA

Among the most mind-bending Hubble photos is its extended look at tiny patch of the celestial sky, encompassing an area less than 1/30th the diameter of the full moon (or the width of a dime 75 feet away.) The Hubble Deep Field, released in 1996, shows a bewildering array of almost 3,000 galaxies, challenging the idea that galaxies can be neatly classified as "spirals" or "ellipticals."

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Astronomers made another deep field survey a year later to verify their findings. They not only found the original image representative of the universe, but bagged a quasar in the process. That served as a cosmological lighthouse to illuminate matter between the quasar and Earth. Other space- and ground-based telescopes followed up with long observation periods of the same regions, adding details and diversity.

The Hubble Extreme Deep Field shows about 5,500 galaxies, the faintest of which are one ten-billionth the brightness of what the human eye can see. | NASA/ESA/G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz)/R. Bouwens (Leiden University)/ HUDF09 Team

Buoyed by the Hubble Deep Field, astronomers in 2004 began a new project, called the Ultra Deep Field, which made use of the new capabilities of the Advanced Camera for Surveys that was installed during a 2002 shuttle servicing mission. This time, Hubble was pointed at a small slice of the constellation Fornax (the Furnace). It revealed the most distant galaxies that can be seen in visible light.

Hubble made additional observations of its original Deep Field and the Ultra Deep Field targets with its near-infrared camera, which turned up even more distant galaxies. The Ultra Deep Field then benefitted from additional infrared scans after a new instrument was installed during the final servicing mission in 2009. Scientists then combined 2,000 exposures, ranging from the ultraviolet to the infrared, that were taken of the same region between 2002 and 2012 into the Hubble Extreme Deep Field, released in September 2012.

Hubble drifts away from the space shuttle Atlantis, which flew a fifth and final servicing call in May 2009 | NASA

It has been almost six years since human eyes have seen Hubble, at least up close. When skies are clear, the telescope can sometimes been seen soaring through twilight or predawn skies (you can track when it will be visible in your neck of the woods at www.n2yo.com).

During the last space shuttle servicing mission to Hubble, astronauts installed a docking ring on the telescope so a future spacecraft can be attached to drive it into the atmosphere for incineration. Long before then, NASA plans to have its successor, the infrared James Webb Space Telescope, flying 1 million miles away from Earth to catch the faintest lights from the universe's baby days.

MORE: Hubble at 25: Space Telescope's Top Science Discoveries