Before they open the lucrative space tourism business to the public, Richard Branson-owned Virgin Atlantic and Jeff Bezos-led Blue origin are fighting and the online feud has only turned ugly this time.
While billionaire Branson is set to fly to space aboard his Virgin Galactic's VSS Unity spaceplane on July 11, Amazon Founder Bezos is expected to take off in his own space tourism rocket on July 20.
Blue Origin tweeted a chart on Friday, two days before Branson's flight, comparing Virgin Galactic's spaceplane to Blue Origin's New Shepard on window size, vehicle type, escape system, and other factors.
"From the beginning, New Shepard was designed to fly above the Karman line, so none of our astronauts have an asterisk next to their name," the company said in its tweet.
The Karman line, 100 kms above the ground, is the boundary of space.
Blue Origin's New Shepard rocket aims to launch its crew capsule just beyond the Karman line for a few minutes of weightlessness, while Virgin Galactic's SpaceShipTwo spaceplane flies 89 kms high - just over the boundary of space defined by the US government, reports The Verge.
Blue Origin further tweeted: "For 96 per cent of the world's population, space begins 100 km up at the internationally recognised Karman line."
Reacting to the tweet, Nicola Pecile, a Virgin Galactic test pilot, posted: "This pissing contest about the Karman line is so childish that is getting really embarrassing to watch".
"Flying above 100K ft is already so complicated that anyone doing so should deserve a special recognition," Pecile tweeted. The tweet was later deleted.
In another tweet, he cited Virgin Galactic's first spaceflight with humans in 2018 and added that Blue Origin "has flown only mannequins so far."
Earlier, Blue Origin's CEO Bob Smith wished Branson well after Virgin's announcement, but said that "they're not flying above the Karman line and it's a very different experience."
When Branson was asked on CNBC whether he's trying to beat Bezos to space, he replied: "Jeff who?"
Virgin Galactic has confirmed Branson's flight on July 11 alongside four mission specialists and two pilots.
"I've always been a dreamer. My mom taught me to never give up and to reach for the stars. On July 11, it's time to turn that dream into a reality aboard the next Virgin Galactic spaceflight," Branson said in a tweet.
Last month, Bezos announced a trip to the edge of space aboard his venture Blue Origin's first crewed mission of New Shepard on July 20 with his brother Mark and two others.
On July 1, Bezos announced the fourth crew member -- Wally Funk, a legendary aviator who also holds a ticket for Virgin's VSS Unity.