When it premiered on September 15, 1965, the CBS sci-fi adventure “Lost in Space” met with little enthusiasm from TV viewers. But the show, which originally debuted in black and white, gained popularity during its second month on the air, and eventually cracked the top ten weekly programs by January.

A cosmic variation on Johann David Wyss’s classic novel “The Swiss Family Robinson,” the Emmy nominated series became a beloved pop culture phenomenon when it was picked up for syndication following its cancellation after three seasons.

To mark the show’s 50th anniversary, Twentieth Century Fox Home Entertainment releases a lavish 18-disk Blu-ray boxed set on Tuesday, featuring all 83 episodes of the campy space saga, along with hours of never-before-seen material culled from the personal archives of series creator Irwin Allen.

Allen, best known for the blockbuster disaster movies that he produced in the ‘70s, gained early success as a fantasy TV producer, creating genre shows like “The Time Tunnel,” “Land of the Giants” and “Voyage to the Bottom of the Sea.”

“Irwin was quite a visionary,” said Angela Cartwright, who played teenage space explorer Penny Robinson on “Lost in Space,” and later starred in the 1979 disaster sequel “Beyond the Poseidon Adventure,” which Allen directed. “He knew how to bring excitement every week into peoples’ homes, while also giving them something to think about.”

“I wish Irwin had personally directed more than just the pilot,” said Bill Mumy, whose role on the series inspired the iconic catchphrase “Danger, Will Robinson!”

“He was incredibly ambitious, and laid down an amazing template for the series in that pilot,” Mumy said. “Plus, he dressed in very bright colors and had the first comb-over I’d ever seen!”

Five decades later, Allen’s on-set behavior still amuses the cast.

“We’d lurch back and forth in that spaceship to the sound of Irwin slamming a hammer against an aluminum pail,” Cartwright said. “He’d yell ‘Left! Right! Left!’ And he’d bang on his pail while we stumbled from side to side. It was just so ridiculous!”

“He used a megaphone when he was directing, and I’d think to myself, dude, I’m five feet away from you!” Mumy said. “He was an old time Barnum and Bailey kind of guy, a real showman.”

The commentaries, outtakes and archival footage scattered throughout the Blu-rays paint Allen as a shrewd TV producer whose fondness for elaborate special effects often put the series behind schedule.

“He wasn’t the easiest person to work for, and was under a lot of stress to get the show completed,” Cartwright adds. “But he had great ideas and knew how to make them happen.”

“The buck stopped with Irwin,” Mumy said. “He was very aware of his budget, and used to walk on to the set each day after lunch and stand over by the director tapping his watch. That’s all it would take. Just a few little taps that meant time is money.”

Though the series spawned a big-budget theatrical remake in 1996 and continues to run on classic TV cable networks like Me-TV, it never achieved the same level of cultural fame as “Star Trek,” which premiered during its second season.

“We never thought of ‘Star Trek’ as competition,” Mumy said. “For me, ‘Star Trek’ was a military show and ‘Lost in Space’ was a family show, and they were both set in deep space, and they were both ridiculously campy and ridiculously cool!”

In addition to the bizarre aliens, stylish robots and aluminum foil space suits, “Lost in Space” is notable for featuring one of composer John Williams’ most recognizable television scores.

“Williams made a name for himself in those first few episodes,” Mumy said. “We had other composers later on, but if you listen to Williams’ main themes that ran throughout the entire series, they’re beautiful! They’re haunting! They’re one of the reasons why the show still resonates with viewers the way it does.”

Reflecting on the show’s enduring popularity, Cartwright and Mumy believe it comes down to one word: family.

“It’s the family aspect that really captures people’s imaginations,” Cartwright said. “Fans who grew up with the show are watching it with their young kids today. There’s a feeling of innocence to it that people enjoy passing on to their children and grandchildren.”

“Everyone can relate to the family dynamic,” Mumy adds. “And that concept is a perfect canvas to let your imagination loose in, whether you’re eighty or you’re eight.”