Branson and Bezos are currently locked in a race – though they have not explicitly said called it such – to get to space first. Branson will set off this weekend, with Bezos leaving later this month.
But Bezos’s rocket firm, Blue Origin, has now suggested in a tweet that Branson will not actually be making it to space when he completes the journey aboard Virgin Galactic’s spaceplane. He will not be going high enough to make it into what most people refer to as space, the company said.
It contrasted that with its New Shepard rocket, which will carry people to a higher altitude.
“From the beginning, New Shepard was designed to fly above the Kármán line so none of our astronauts have an asterisk next to their name,” it wrote in a tweet. “For 96 per cent of the world’s population, space begins 100 km up at the internationally recognized Kármán line.
“Only 4 per cent of the world recognizes a lower limit of 80 km or 50 miles as the beginning of space. New Shepard flies above both boundaries. One of the many benefits of flying with Blue Origin.”
It also said that Virgin Galactic only had “airplane-sized windows” while its own New Shepard has the “largest windows in space”.
Blue Origin said that Virgin Galactic’s craft does not have an “escape system” and criticised its impact on the ozone layer, pointing to a study by the Aerospace Corporation.
It also pointed out that it has a rocket-style vehicle, in contrast with Virgin Galactic’s “high altitude airplane”.
Bezos’s trip will be the first crewed test of his company’s New Shepard rocket. It is the first time Branson’s Unity space plane has flown with a full set of six people, though it has completed various crewed tests in the past.
Branson has explicitly denied that the two billionaires are racing to space, though he has admitted that people are unlikely to believe him.
Bezos was first to announce his trip, setting a date last month. Soon after that, Branson said that he would also be testing out his company’s spacecraft – and that his journey would happen before Bezos’s.
Since then, commentators have pointed out that the two billionaires appear to be locked in a fight to prove themselves to be the first to make the journey, as well as to bring publicity to their respective space tourism ventures.
Though the two have personally refused to be drawn into any such competition, the tweets from Blue Origin suggest that there is at least some competition between their two firms.
The launch window for Branson’s trip opens on Sunday afternoon UK time. Bezos will fly on 20 July, with the other three seats taken by flight pioneer Wally Funk, his brother Mark and another person who paid $28 million in a public auction and whose identity is yet to be announced.
Ms Funk is also one of a number of people who bought tickets on board a future Virgin Galactic flight, as part of a programme that allowed people to book tickets that can be used when the company begins its space tourism operations.