The Hubble Space Telescope has revolutionized our understanding of the universe with images unprecedented in scientific value. I was privileged to have witnessed the beginning of its mission 19 years ago, when I was entrusted with releasing Hubble from the Space Shuttle Discovery. Seven years later, I returned to the orbiting observatory as part of a mission to repair and upgrade its scientific capabilities.

Part of Hubble’s fascinating story captures the challenges and rewards of maintaining and improving the observatory. This week, astronauts visited Hubble for a final servicing mission to install two new instruments and upgrade its systems, thus extending its remarkable life at least five years, while improving our ability to see the universe in ways I wouldn’t have imagined in 1990.

Hubble is one of robotic exploration’s most stunning achievements. But its story would have turned out differently without human space flight. Following the original launch, scientists discovered a flaw in the telescope’s primary mirror — quickly making Hubble the object of jokes on late night talk shows.

Innovative engineers developed corrective optics — eyeglasses, really — to compensate for the effects of the mirror’s shape while operations teams at NASA and contractor sites developed techniques to install them. During space shuttle mission STS-61 in December 1993, billed as NASA’s most important mission since Apollo 11, my colleagues installed the optical fixes, as well as new instrumentation, enabling Hubble to reach its original specifications for resolution and sensitivity.

I returned to Hubble on the second servicing mission in 1997 to install instruments expanding Hubble’s wavelength sensitivity. In the 12 years since, NASA crews have performed maintenance on the telescope to continually improve its capability.

Among its most significant accomplishments, Hubble helped astronomers establish the universe’s age at 13.7 billion years and provided evidence for the existence of mysterious “dark energy,” which is causing the expansion of our universe to accelerate. An instrument we delivered in 1997 confirmed the presence of a black hole at the center of an active galaxy.

One of the more famous Hubble images is a 10-day exposure of what we thought was an empty region of sky near the Big Dipper. This image, known as the “Hubble Deep Field,” revealed an amazing number of galaxies, some having formed when the universe was very young. Recently, Hubble has directly captured images of planets around other stars. All of these accomplishments were enabled by the servicing missions and demonstrate the tremendously productive relationship between humans and machines conducting science in space.

The successor to Hubble, the James Webb Space Telescope, is scheduled for launch in 2013. The Webb Telescope will have a mirror more than twice the size of Hubble’s and will be able to look for the first galaxies that formed in the early universe. It will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own solar system.

It isn’t designed to be serviced. Its intended orbit 932,000 miles from Earth will likely put it out of reach of astronauts, at least in the near-term. But, perhaps heeding the lessons of Hubble, NASA has contemplated installing a device that would allow it to be captured by a robot or piloted spacecraft in the future. You never know if maintenance needs will arise!

As we look forward to the Webb Telescope launch, the Ares V cargo launch vehicle is under development as part of NASA’s Constellation Program. Ares V could enable even larger, more sophisticated scientific spacecraft to travel the universe and deliver cargo for humans on the Moon. With the ability to put more than 400,000 pounds into low Earth orbit, robotic exploration will benefit as well, giving spacecraft developers more latitude in matching the design to the mission.

With this kind of lift capability the telescopes of the next generation will make Hubble look like a “Model T.” Also, the capability to have astronomical facilities on the Moon offers the opportunity to conduct studies that would otherwise be impossible from Earth. Radio astronomy done on the Moon’s far side would enable sensitive scientific observations in wavelength regions that are dominated by terrestrial interference. Already, NASA has commissioned studies by MIT and the Naval Research Lab to develop plans for an array of radio telescopes on the far side of the moon.

When you witness the awe-inspiring Hubble repair mission with astronauts so delicately and skillfully working to extend Hubble’s life one last time, remember what this achievement represents — the unique synergy of human ingenuity and technological prowess that will serve the space program into the future.