William Shatner's Family Tried Talking Him Out of Space Flight — But He Said 'Save Your Breath'

As Captain Kirk on Star Trek, William Shatner became synonymous with space exploration in the 1960s — but several decades later, his family wasn't thrilled when the 90-year-old actor actually wanted to take a real-life rocket ride. In fact, they told him not to go.

Speaking with PEOPLE less than 24 hours after blasting out of this world in Jeff Bezos' Blue Origin New Shepard vehicle, Shatner opens up about his ex-wife and daughters' objections to the once-in-a-lifetime opportunity.

"I said, 'I gotta go. Everything's fine; don't worry about it. It's very, very safe,' " he recalls in this week's issue. "And it is! [I said] 'Don't worry. Or if you worry, know that everything is going to be fine. I am going; save your breath.' [And they said] 'But Dad, why don't you go to Australia instead?' "

For Shatner, the wonders Down Under couldn't compete with the promise of zero gravity. So he proceeded with the plan, which came to fruition after his friend and Better Late Than Never producer, Jason Ehrlich, floated the idea a year and a half ago.

Still, "There were moments when I thought, 'I wonder if maybe I am too old,' " he admits.

But he passed the preflight fitness routine: "It all worked out, and I wasn't too old."

The big day finally came on Wednesday, Oct. 13. Strapped into one of the capsule's seats above Blue Origin's launchpad in West Texas, Shatner waited for liftoff alongside his three other crew members: Audrey Powers, Blue Origin's vice president of mission and flight operations; Chris Boshuizen, co-founder of Planet Labs; and Glen de Vries, co-founder of Medidata Solutions.

For more on William Shatner's record-making trip, pick up the latest issue of PEOPLE, on newsstands Friday, or subscribe here.

After a few delays, "the hydrogen and the oxygen ignite, and you feel it, because you're lying down," he explains. "You feel it with your whole back, and you think, 'Oh my God, I hope it doesn't explode.' "

Everything went as planned, though, and within minutes, Shatner became the oldest person to ever cross the Kármán line — the internationally recognized border of space.

"I'd rather make history in other ways than being the oldest man in space," says The UnXplained host and sometime-singer, whose latest album, Bill, dropped in September.

"All these years I've sort of jokingly said, 'Oh no, I'm not [that old]. They made a mistake on my birth certificate,' " Shatner adds.

His age was irrelevant as he looked at the planet through New Shepard's expansive windows with childlike awe.

"Weightlessness. Oh, Jesus," Shatner remarked in a clip from the 11-minute mission.

His crew mates laughed in amusement.

"No description can equal this," he added. "Wow."

The group was soon on their way back to Texas. Feeling the forces as the capsule hurtled through the atmosphere, "I still was filled with apprehension," he says. "When the five Gs was on us, I thought, 'Wow, can I take more? If it gets any worse than this, can I take it?' "

After a perfect parachute landing, Shatner found himself walking out of the capsule as his eyes welled with tears of joy.

"Everybody in the world needs to do this," Shatner told Bezos, whose company is selling New Shepard rides as the private space race heats up. "Everybody in the world needs to see."

He's since had time to process those moments in space.

"I experienced something so emotional about life and death, and the destruction of the planet, and the preciousness of everything that I'm connected with," Shatner tells PEOPLE.

"It sharpens everything about your life," he adds. "It sharpens your awareness of the beauty of the Earth and your loved ones and all the things."