It's been branded the "battle of the billionaires" but the new space race may not be as ill-tempered as you might expect.
SpaceX's Elon Musk, Virgin Galactic's Richard Branson and Blue Origin's Jeff Bezos all have space tourism and exploration plans at various stages of completion - but that hasn't stopped two of them, at least, from supporting each other.
Virgin Galactic told the Wall Street Journal that Musk, who has set his sights on colonising Mars, has bought a ticket to fly on the company's spacecraft for an unspecified future flight.
That came after the company completed its first fully crewed spaceflight, with Branson on board SpaceShipTwo. The British billionaire told a press conference afterwards that the Tesla CEO had shown up before the flight to wish him well.
"It was so great to find Elon in my kitchen at 3 o'clock," Branson said. He then referred to Musk as a "friend" in a subsequent tweet.
Their relationship with Bezos might not be as affable, however.
In April, Musk appeared to troll the former Amazon CEO after Bezos had tried to challenge the awarding of a contract from the US Government to SpaceX to build a spaceship to deliver astronauts to the moon.
Musk fired back at the news with a tweet that said: "Can’t get it up (to orbit) lol".
And Blue Origin appeared to try and throw some shade at Branson ahead of his space flight on Monday, NZ time, saying its spacecraft was designed to fly above the Kármán Line.
"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. For 96 percent of the world’s population, space begins 100km up at the internationally recognized Kármán line," it wrote.
The Kármán line is defined by Fédération Aéronautique Internationale as the boundary between the Earth's atmosphere and outer space, and Blue Origin intends to offer 10 minutes of flight at that altitude.
Virgin Galactic's spacecraft will fly to around 92km above Earth's surface, below the Kármán line but above what NASA defines as the beginning of space, Endgadget notes.
Bezos is due to take to the skies on July 20, US time, accompanied by his brother Mark and "honoured guest" 82-year-old Wally Funk, who spent six decades trying to reach space. A mystery person who paid US$28 million for a seat will also be onboard.
