A SpaceX Falcon 9 rocket launch to the International Space Station today has been postponed, with officials citing problems with ground systems.
The SpaceX Dragon Crew-6 mission was scheduled to depart the Kennedy Space Center in Florida at 6.45am Irish time, carrying two NASA astronauts, a Russian cosmonaut and the second Emirati to voyage to space.
But just two minutes before lift-off, the launch was called off, or "scrubbed".
"Today's #Crew6 launch has been scrubbed due to an issue with ground systems," NASA posted on Twitter.
SpaceX said shortly after that it had begun unloading fuel from the rocket and the crew would disembark.
The launch will be rescheduled for a later date.
Standing down from tonight's launch of Crew-6 due to a TEA-TEB ground system issue. Both Crew-6 and the vehicles are healthy and propellant offload has begun ahead of the crew disembarking Dragon
— SpaceX (@SpaceX) February 27, 2023
The crew Dragon capsule, dubbed Endeavour, was scheduled to dock with the ISS at 7.38am tomorrow.
As the sun set yesterday, the US space agency had expressed confidence that the launch was a go.
"Countdown to liftoff!" NASA tweeted, as it promoted its livestream of the launch.
NASA's Stephen Bowen and Warren Hoburg, Russia's Andrey Fedyaev and Sultan al-Neyadi of the United Arab Emirates are to spend six months on the orbiting space station.
Mr Neyadi, 41, will be the fourth astronaut from an Arab country and the second from the oil-rich UAE to journey to space; his compatriot Hazzaa al-Mansoori flew an eight-day mission in 2019.
Mr Neyadi described the upcoming mission as a "great honour."
Warren Hoburg, the Endeavour pilot, and Andrey Fedyaev, the Russian mission specialist, will also be making their first space flights.
Sunset at the pad pic.twitter.com/K0MUpYc6sM
— SpaceX (@SpaceX) February 26, 2023
Mr Fedyaev will be the second Russian cosmonaut to fly to the ISS on board a SpaceX rocket. NASA astronauts fly regularly to the station on Russian Soyuz capsules.
Space has remained a rare venue of cooperation between Moscow and Washington since the Russian offensive in Ukraine placed the two in sharp opposition.
Such exchanges have continued despite those tensions.
Mr Bowen, a veteran of three space shuttle missions, said politics rarely come up while in space.
"We're all professionals. We keep focused on the mission itself," the mission commander said. "It's always been a great relationship we've had with cosmonauts once we get to space."
While on board the ISS, the Crew-6 members will conduct dozens of experiments including studying how materials burn in microgravity and researching heart, brain and cartilage functions.
The current crew will be the sixth to be transported by a SpaceX rocket to the ISS. The Endeavour capsule has flown into space three times.
NASA pays the private SpaceX company to ferry astronauts to the flying laboratory roughly every six months.
The space agency expects Crew-6 to have a handover of several days with the four members of the SpaceX Dragon Crew-5, who have been stationed on the ISS since October. Crew-5 will then return to Earth.
Also on board the ISS are cosmonauts Dmitry Petelin and Sergei Prokopyev, as well as NASA astronaut Frank Rubio.
They had been scheduled to return home on 28 March but the cooling system of their Soyuz MS-22 capsule was damaged by a tiny meteoroid in mid-December while docked with the ISS.
An uncrewed Russian Soyuz capsule, MS-23, took off on Friday from Kazakhstan to bring the three astronauts home. They are now scheduled to return to Earth in September.
The ISS was launched in 1998 at a time of increased US-Russia cooperation following the Cold War space race.
Russia has been using the aging but reliable Soyuz capsules to ferry astronauts into space since the 1960s.
But in recent years, Russia's space programme has been beset by a litany of problems that have led to the loss of satellites and vehicles.
