WASHINGTON, UNITED STATES - Three US astronauts and a Russian cosmonaut arrived Tuesday at the International Space Station for a six-month mission on board the orbiting laboratory.

During their stay, in which they are rotating in to replace departing crew, some 200 scientific experiments are scheduled to be carried out.

The quartet blasted off from Florida late Sunday aboard a SpaceX Falcon 9 rocket.

The capsule docked with the ISS and its hatch was opened at 3:50 am Tuesday US eastern time (0850 GMT), with the smiling new arrivals hugging their colleagues as they entered, a live feed of the docking showed.

A SpaceX Falcon 9 rocket with the Crew Dragon Endeavour capsule sits on launch pad LC-39A at Kennedy Space Center ahead of the Crew-8 Mission in Cape Canaveral, Florida, on March 3, 2024. - Three US astronauts and a Russian cosmonaut are set to launch for the International Space Station on March 3 at 10:53pm (0353 GMT, March 4). (Photo by CHANDAN KHANNA / AFP)

This is the eighth standard ISS crew rotation mission performed by SpaceX for the US space agency NASA, reflected in the mission name: Crew-8.

American Michael Barratt is the only Crew-8 astronaut to have already visited the space station. The ISS stay is the first for Americans Matthew Dominick and Jeanette Epps, and Russian Alexander Grebenkin.

They join seven crew already on board the ISS.

After a transition period of a few days, the four members of Crew-7 -- from Denmark, Japan, Russia and the United States -- will return to Earth aboard another SpaceX capsule.

A SpaceX Falcon 9 rocket with the Crew Dragon Endeavour capsule carrying the Crew-8 mission launches from launch pad 39A at NASA's Kennedy Space Center in Florida on March 3, 2024. - Three US astronauts and a Russian cosmonaut launched for the International Space Station. They will conduct over 200 scientific experiments and technology demonstrations during their planned 180-day mission to the International Space Station. (Photo by CHANDAN KHANNA / AFP)

NASA and Russian space corporation Roscosmos, which jointly operate the ISS, have established an astronaut exchange program, each taking turns to send crew members to the outpost.

The program has been maintained despite deep tensions over the war in Ukraine, and the ISS is now one of the few areas of cooperation between Washington and Moscow.