By Chris Skeldon 
A SpaceX mission launched today with two passengers on board, instead of the initially planned four, in order to leave two empty seats for American astronauts on the International Space Station.
The two American astronauts have been on the International Space Station for several months due to malfunctions in a Boeing spacecraft, according to Agence France-Presse.
The Falcon 9 rocket took off from Cape Canaveral, Florida (USA) at 1:17 pm local time (17:17 GMT). The launch took place from a new launch pad used for the first time on a manned mission.
NASA Administrator Bill Nelson said: “Congratulations to NASA and SpaceX on a successful launch. This is an exciting time for exploration and innovation.”
NASA astronaut Nick Hague and Russian cosmonaut Alexander Gorbunov are on board the spacecraft.
Their return is scheduled to take place in February. The astronauts will be accompanied by astronauts Butch Wilmore and Sonny Williams, who launched in early June aboard a new spacecraft developed by Boeing, Starliner, on the first manned test flight to the space station (International Space Station).
The spacecraft was supposed to return to Earth after eight days, but problems discovered in its propulsion system led NASA to question its reliability.
After weeks of testing, the space agency ended up sending the empty Boeing capsule to Earth and decided to return the two crew members who drowned on a SpaceX mission.
Billionaire Elon Musk's company is responsible for the regular crew rotation mission to the International Space Station, which, like all other missions, is expected to last about six months.
However, the Crew-9 launch was postponed from mid-August to late September to give NASA teams more time to decide on Boeing's spacecraft.
The launch had to be postponed again for a few days due to the passage of Hurricane Helen, which struck Florida this week.
SpaceX's Dragon spacecraft is expected to dock with the International Space Station at approximately 21:30 GMT on Sunday.
After a transition period with the four members of the previous mission, Crew-8, they will return to Earth aboard another SpaceX spacecraft.
In total, Nick Hague and Alexander Gorbunov will spend about five months on the ISS. Butch Wilmore and Sonny Williams will stay for approximately eight months.
At a press conference in early September, they both confirmed that they were coping well with their long stay.
“The transition wasn't very difficult,” Sonny Williams said. “We both come from the Navy, and have been deployed before. We're not surprised when assignments change.”
It was planned to conduct about 200 scientific experiments during the 9th crew's stay in the flight laboratory