SEATTLE -- With billions of dollars on the line and scientific breakthroughs in the balance, NASA chose Seattle's Greg Johnson to lead that mission.

Greg has spent his entire adult life in the pilot seat. But this is his first adventure into space.

"It's pretty daunting," he said. "I think I find it as a challenge. I enjoy challenges. I think I'd never had my hands on a $2 billion vehicle."

He graduated from West Seattle High School in 1972 with an eye on the sky. Almost immediately, he hooked up with Kenmore Air flying sea planes.

He landed on glaciers to deliver supplies to oil crews in Alaska.

When that wasn't enough, Greg joined the Navy and flew experimental aircraft. In 1990, he became a NASA test pilot.

"That's kind of how I got there," he said. "Not a lot of big planning, but certainly looking for exciting, challenging things to do."

Greg's father Raleigh Johnson always planned on his son following his footsteps. He was sure his son would be a Boeing engineer.

When asked if he thought Greg would be doing something special that the world would notice, Raleigh replied: "I didn't think it would go this far, but I knew he would be doing something fine."

So when Greg wanted to fly, dad made him study first. He even paid for an aerospace engineering degree at the University of Washington, just in case his son's flight path fell short.

But Greg refused to settle. In 1998, NASA asked him to become an astronaut.

"And I tell people, whoever will listen - whether they want to listen or not - my son is an astronaut," Raleigh Johnson said.

Greg said it's about learning new things. "It's not about the title," he said.

Greg has trained for years for this one shot. He's run through the mission dozens of times on the ground, knowing he's in charge of safely getting the astronauts to and from the Hubble Space Telescope.

It's a responsibility so intense, he said he won't have time to reflect on personal achievement.

"I've got to be game on, watching those systems, make sure they go right," he said. "If they don't -- listen to the ground and go through the procedures to save them. Or do what we need to do to abort."

Greg knows the entire crew is counting on him.

Before the scheduled launch was scrubbed in October, Greg gave his dad a flight patch that he designed. It was a small "thank you" for the life lesson that pushed him into space.

He'll remember that lesson just before lift-off.

"Pursue your passion. Always do your best," Greg said. "And my Dad always told me that. always do your best, and if you have, then you'll have no regrets."

Greg Johnson's done his best, and his career is about to reach new heights.

As the pilot, Greg's big jobs are take-off and landing. The rest of the astronauts will be in charge of repairing the Hubble.

Greg is filming the mission for Imax, and he expects the movie to be in theaters next year.

By the way, his father was at Cape Canaveral to see his son make history Monday. So too were his Navy buddies from the Whidbey Island Naval Station and his friends from West Seattle High School.