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Hubble Space Telescope Turns 25, With Discoveries and Drama Galore

Image: Hubble's farewell

The Hubble Space Telescope, as seen from the space shuttle Atlantis, goes its way after a final orbital servicing mission in 2009. NASA

At the ripe old age of 25, the Hubble Space Telescope is arguably the best-known science instrument in the world — but that's only partly due to the scientific wonders it has revealed.

To appreciate the full significance of the $2 billion orbiting observatory's place in science and culture, you have to factor in the human drama behind Hubble's ups and downs, said Mario Livio, an astrophysicist at the Baltimore-based Space Telescope Science Institute.

"What has been very unique to Hubble is that it has really taken the excitement of discovery, which normally only the scientists involved enjoy, and has made the general public part of that," Livio told NBC News.

Celebrating 25 Years of Images From the Hubble Space Telescope 1:20

The idea of sending a large, general-purpose telescope into orbit dates back to the 1940s, when namesake astronomer Edwin Hubble was still working out the implications of his discovery that the universe was expanding. Scientists and engineers built the instrument over the course of a decade — but Hubble's "birth" is marked on the calendar as April 24, 1990, when the 43.5-foot-long (13.2-meter-long) telescope was launched into space aboard the shuttle Discovery.

After Hubble was deployed, astronomers assumed the drama was over. But the first fuzzy pictures to come down revealed that something had gone horribly wrong. Eventually, the Hubble team figured out that the curve of the telescope's main mirror was off by about a millimeter — enough to ruin the focus.

"We went from being the heroes of the science world to just wanting to hide," said John Troeltzsch, a project manager at Ball Aerospace who was part of the Hubble crisis team and is now working on the Sentinel space telescope.

Recalling redemption

The story of how scientists, engineers and astronauts redeemed themselves and rescued the telescope — by installing corrective lenses during a series of five high-tension spacewalks in 1993 — is being recounted repeatedly this week for the 25th anniversary of Hubble's launch:

The drama has continued since the '90s for most of Hubble's life. Four more space shuttle missions were devoted to upgrading Hubble's instruments, including a final overhaul in 2009 that almost didn't happen.

"The whole story of Hubble being renewed is really critical to its success," said Patrick McCarthy, who was part of the science team for the telescope's Wide Field Camera 3 and is now director of the Giant Magellan Telescope Organization.

Audio: Spacewalker Story Musgrave on Hubble's Meaning

Quantity and quality

Hubble's orbital odometer has now passed the 3.4 billion-mile (5.5 billion-kilometer) mark, and from its 350-mile-high (560-kilometer-high) orbit, it has sent back more than a million observations that tally up to more than 100 trillion bytes of data.

The discoveries are notable for their quality as well as their quantity:

Exotic discoveries aren't the only reasons for Hubble's popularity. It was built to provide pictures across a wide range of wavelengths, from ultraviolet to near-infrared, but the sweet spot is in the visible part of the spectrum. "Hubble provides the images that match your eyeballs," said Mark LaPole, director of advanced imaging at Ball Aerospace.

The result? Looking at Hubble's pictures make you feel as if you're on the final frontier yourself — even though the colors on that frontier might sometimes be artificially enhanced.

Gallery: Classic Hits From Hubble

Mission accomplished?

So what's next for Hubble? Six years ago, the final servicing mission left the space telescope in its best condition ever. "The telescope has been performing extremely well," said Ken Sembach, the head of the Hubble mission at the Space Telescope Science Institute. For now, the discoveries will continue.

The next big project on the horizon is the $8.8 billion James Webb Space Telescope, which is on track for launch in late 2018 after a series of cost overruns and schedule slips. JWST, which is named after NASA's second administrator, is bigger and more powerful — with a foldable 21-foot (6.5-meter) mirror that dwarfs Hubble's 8-foot (2.4-meter) primary mirror.

How the Hubble Telescope Has Changed the Way We See Space 0:51

But the Webb telescope is not designed to be serviced in space. Instead, it will be on its own, a million miles from Earth at a vantage point known as Earth-Sun L2. It's also optimized to see infrared wavelengths rather than visible light.

NASA wants Hubble to last until at least 2020, so that there's some overlap with JWST's observations of far-off galaxies and exoplanets. A new generation of ground-based telescopes, including the Giant Magellan Telescope, also will complement those observations. There's talk about even farther-out space telescopes to come, including a Wide-Field Infrared Survey Telescope, or WFIRST, and a 12-meter space telescope capable of analyzing exoplanetary atmospheres.

"If we learned a lesson from Hubble, it's that we shouldn't be afraid to think big," Livio said.

During that last servicing mission, Hubble was outfitted with a docking adapter that would make it easier for a robotic tug to pull the telescope down to its destruction in a controlled atmospheric re-entry — perhaps sometime in the 2030s. But LaPole hopes that Hubble will last long enough to allow for yet another service call, perhaps by astronauts riding new breeds of spaceships.

"All of us folks who work on it would love to see that happen," LaPole told NBC News. "It's our child, and we want to see it continue."

Flash Interactive: How Hubble Works