William Shatner will be shot into space aboard Blue Origin - the rocket system developed by Amazon founder Jeff Bezos - later today.
The trip, which will last around 10 minutes, will put the legend of both the big and small screens around 60 miles above the earth's surface.
Shatner will become the oldest person to go to space, taking the record from US aviator Wally Funk, 82, who flew in an earlier Blue Origin mission.
But the actor once turned down a space flight from another billionaire, Richard Branson, because he'd have to pay for it.
Today's launch of the ship named 'New Shepard' after Alan Shepard, the first American in space, is set to take place at 0900 local time or 1500 BST.
During the trip it is expected Shatner will experience a feeling of weightlessness as he travels towards the ship's maximum altitude.
It is reported that the earth's curvature will be visible out of New Shepard's windows.
"There is this mystique of being in space and that much closer to the stars and being weightless," the Canadian-born actor said.
"I shall be entranced by the view of space. I want to look at that orb and appreciate its beauty and its tenacity.
"I want to have vision, I want to see space. I want to see the Earth. I want to see what we need to do to save Earth.
"I want to have a perspective that hasn’t been shown to me before."
What is William Shatner's net worth?
According to website Celebrity Net Worth, Shatner has a net worth of $100 million, which converts to around £73 million.
After graduating from university in Canada, he trained as a classical Shakespearean actor before playing a number of roles at the Stratford Shakespeare festival.
He shot to fame during the original series of Star Trek in 1966, five years after his Blue Origin ship's namesake – Alan Shepard – first entered space.
It is reported he earned $3,500 per episode during the cult show's first season.
Despite his massive wealth, Shatner doesn't seem keen on paying for space travel.
It was reported in 2013 that Shatner had turned down the chance to fly on Sir Richard Branson's Virgin Galactic — and Blue Origin's main competition — which took Sir Richard to the edge of space in July.
Sir Richard told The Sun that Shatner had turned down the offer due to his fear of flying.
But in 2011 the actor said he had turned down the offer because the billionaire allegedly wanted him to pay.
"He wanted me to go up and pay for it and I said: 'Hey, you pay me and I'll go up. I'll risk my life for a large sum of money.' But he didn't pick me up on my offer," Shatner told reporters.
