Astronaut Dave Mackay, who hails from Helmsdale in Sutherland, will be responsible for navigating Virgin Galactic’s Unity rocket plane into space on Sunday.
The mission, the first fully-crewed flight to the edge of space, has been delayed by 90 minutes due to adverse weather conditions overnight at Spaceport America.
The launch time from New Mexico is now set for 3.30pm UK time.
Billionaire businessman Sir Richard will become the first owner-astronaut to take part in a mission, beating Amazon founder Jeff Bezos, who plans to reach space in his own rocket through his Blue Origin company.
Tourists are expected to pay 250,000 US dollars (£180,000) for a spaceflight on Virgin Galactic, which includes four minutes of zero gravity.
While ticket prices will be out of reach for all but the wealthiest of people, test pilot Dave Mackay says he’s confident that trips into space will soon become the norm and that most of humanity will be capable of taking them.
Speaking to the BBC ahead of Sunday’s launch, Mr Mackay said: "We are confident that the vast majority of the population of the Earth are capable of going on this space flight”.
Mr Mackay, 64, will be one of two pilots and four "mission specialists" - including Sir Richard - on board, and says the experience of viewing the Earth from the upper limits of our atmosphere has left him awestruck.
The former RAF pilot said: "It affected me more than I anticipated - the incredible blackness of space.
"If you think about it, when you're on Earth and are looking horizontally you're looking through a lot of moisture and dust particles and even on a clear day you're still looking through miles and miles of pollution.
"But when you're up in space you're looking directly down... the colours on the ground look incredibly vivid and in contrast to this incredibly dark sky.
"And then on top of all that you see so much of the curvature of the Earth and you get a sense of scale of the planet and you realise it's not very big."
Meanwhile, the Sunday Times newspaper reported that Elon Musk – who owns rival exploration company SpaceX – has paid for a seat on a future Virgin voyage.
Mr Musk paid a 10,000-dollar (£7,000) deposit to reserve a seat but no date for his flight has been specified.
Sir Richard confirmed the purchase in an interview with the newspaper, saying he might reciprocate by booking a ticket on a SpaceX flight in the future.
“Elon’s a friend and maybe I’ll travel on one of his ships one day,” he said.
Amid what has been dubbed the billionaires’ space race, SpaceX has launched dozens of rockets, including manned flights, but Mr Musk himself has not yet flown on any.
The company is due to launch its first fully private spaceflight in the autumn.