NASA’s Hubble space telescope was launched into orbit aboard the Space Shuttle Discovery on April 24, 1990, kicking off an incredible three decades of discovery.

As Hubble prepares to celebrate its 30th anniversary, former NASA astronaut Mike Massimino told Fox News about his trips to the orbiting space telescope. Massimino, who is now a professor at Columbia University’s School of Engineering, flew two space shuttle missions to the Hubble Space Telescope during his NASA career.

“I think it’s the greatest scientific instrument ever built,” he told Fox News. “I think it’s an amazing engineering accomplishment.”

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The telescope, which is about the size of a school bus, has shown the birth of stars and even the creation of black holes. NASA notes that it has also captured Jupiter’s Great Red Spot shrinking over time and made discoveries such as planetary moons and icy objects beyond Pluto.

Hubble, which travels at 17,000 mph, has taken more than 1.4 million observations and captured light from distant galaxies that took more than 13.4 billion years to reach us, according to NASA.

Hubble’s eventual successor, the James Webb Space Telescope, described by NASA as the most powerful and complex space telescope ever built, is scheduled to launch on March 30, 2021. However, work on the telescope was paused amid the coronavirus pandemic.

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Massimino was a graduate student at MIT when Hubble launched back in 1990. Some 12 years later, he would get the chance to work on the orbiting telescope. The astronaut made his first trip to the telescope in 2002 and also took part in the final servicing mission to Hubble in May 2009.

He compared his Hubble missions to “oil changes,” replacing worn out parts and servicing the telescope. The astronaut racked up just over 30 hours over the course of four spacewalks on his missions.

During his final trip, he was in a tense situation when attempting to remove a stubborn handrail in order to replace a power supply on Hubble. A stripped screw meant that he had to rip a handle off the telescope while ensuring that no sharp edges punctured his spacesuit.

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The former astronaut will be featured in the Science Channel documentary “Hubble: 30 Years of Discovery,” which premieres on Sunday, April 19, at 8 PM ET/PT.

Massimino still marvels at Hubble’s ability to withstand extreme heat and cold, as well as micrometeorites. He also highlights the incredible accuracy that Hubble provides when it captures images of distant objects while it is moving.

“It’s like placing a laser on the Empire State Building and hitting a dime on the Washington Monument,” he said.

“It has also shown us how beautiful the universe is,” Massimino said.

Originally designed to last for 15 years, Hubble is still going strong 15 years later. Massimino expects more discoveries from the telescope in the future, whatever they may be.

“What I am excited about is everything coming down the pike,” he told Fox News. “The exciting thing is that you never know.”

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The space shuttle astronaut also discusses his Hubble experiences in his book “Spaceman: The True Story of a Young Boy's Journey to Becoming an Astronaut.”

A version of the book geared toward middle-school-age children has just been published.

“I talk about the telescope and the training,” he told Fox News. “I talk about things I learned in school as a kid and the importance of having a dream and never giving up.”

Follow James Rogers on Twitter @jamesjrogers