Former NASA astronaut Mike Massimino reflects on his role in the story of the Hubble Space Telescope.

Twenty-five years ago, on April 24, 1990, the Hubble Space Telescope soared into orbit. Since then, its great discoveries have been legion, and the story of how it became the most successful and productive astronomical observatory in human history is destined to become legendary.

To help commemorate Hubble’s 25th anniversary, Scientific American collaborated with Nature to produce a series of videos in which individuals closely involved with Hubble reminisced about their favorite images and experiences. You can view those videos here.

For one of those videos, I was honored to talk with Mike Massimino, a former NASA astronaut who is now a professor at Columbia University. We met within the spacious Hubble@25 exhibit at the Intrepid Air, Sea & Space Museum in New York City, where Massimino is senior advisor for space programs.

Few people know Hubble better than Massimino. He is a veteran of two space-shuttle servicing missions to the telescope, STS-109 in 2002 and STS-125 in 2009. STS-125 was the final planned servicing mission, likely the last time humans would ever touch the observatory that reshaped our view of the universe–and ourselves. Present plans call for Hubble to eventually be deorbited, breaking apart and partially melting during a fiery atmospheric reentry before its charred fragments sink to the bottom of a remote stretch of the Pacific Ocean.

In our conversation, framed against the looming shape of the space shuttle Enterprise, which is on permanent display at the museum, Massimino discussed some of his favorite Hubble shots and shared tense moments from his spacewalks. Hubble, he explained, only existed through a synergy of human spaceflight and pure science. Without the space shuttle and the skills of astronauts like Massimino, rejuvenating the telescope through servicing missions would have been impossible.

But that wasn’t all we talked about. After our formal interview, Massimino offered to show me around the Hubble@25 exhibit, which features several of the actual tools he used on-orbit during his servicing missions.

Because there is so little room for error in the harsh environment of outer space, almost every action and movement during a spacewalk is carefully choreographed far in advance. This was particularly true for the Hubble servicing missions, in which astronauts clad in bulky, awkward spacesuits were tasked with performing the equivalent of delicate surgery on an irreplaceable multibillion-dollar telescope. One slip-up, and the telescope could be irreparably damaged, or a life could be lost. To prepare, for years Massimino logged long hours training underwater in NASA’s Neutral Buoyancy Lab, a giant swimming pool that simulates the zero-g conditions of low-Earth orbit.

At the end of our visit, Massimino guided us into a small, darkened room tucked in the back of the Hubble exhibition, which he had co-curated. It was made to seem aquatic with colored lights, video from NASA’s giant pool, and piped-in sounds of burbling respirators. Beneath the belly of a retired space shuttle, a retired astronaut had created a simple simulacrum of the Neutral Buoyancy Lab.

Submerged in the shimmering blue light, in a place meant to mirror where he had spent so much focused time in preparation for fixing Hubble, Massimino seemed at peace. Given the chance, he said, he would be thrilled to go into space again–or, perhaps, back into the crystalline depths of the Neutral Buoyancy pool. But, as he relaxed on a bench, he made it clear he’s happy to stay on Earth, too. As glamorous as riding rockets into orbit is, it’s also more than a little scary:

Hubble@25 will remain at the Intrepid Museum for the rest of the summer. I recommend you visit if you’re in the neighborhood, to directly experience the highs and lows of Hubble’s story, and Massimino’s crucial role within it.