Four astronauts arrive at International Space Station after SpaceX flight

Crew-8 will spend their time carrying out research on stem cells and studying plants

The Nasa SpaceX Crew-8, from left: Michael Barratt, pilot; Matthew Dominick, commander; and mission specialists Alexander Grebenkin and Jeanette Epps in Titusville, Florida, shortly before the space flight. EPA

Barratt waves goodbye to family members before heading to the launch pad at the Kennedy Space Centre in Cape Canaveral, Florida. AFP

Grebenkin, a cosmonaut, walks towards the SpaceX Falcon 9 rocket in Cape Canaveral, which then carried the crew to the ISS. AFP

The countdown in Cape Canaveral is almost complete. AFP

The rocket lifts off from launch pad. AFP

Carrying the crew's capsule, the Falcon 9 rocket lights up the sky over Cape Canaveral. AFP

The four astronauts embark on their journey to the ISS. AFP

Four new astronauts arrived at the International Space Station on Tuesday for a six-month science mission.

The Crew-8 mission, featuring three American citizens and a Russian, arrived on board a SpaceX Dragon capsule at the orbiting laboratory about 24 hours after blasting off from a Florida spaceport.

Crews have occupied the ISS since 2000, with the structure travelling at 8km a second to maintain its orbit of Earth.

"Crew-8’s mission will further the understanding of how humans learn and behave in space and how their bodies respond, and it’s all critical to our lunar exploration," Nasa's associate administrator Jim Free said in a statement.

"We need all of these to come together to understand how people and technologies and systems will behave when we go on longer duration missions.”

They join those already on board the ISS, including Nasa astronauts Jasmin Moghbeli and Loral O'Hara, the European Space Agency's Andreas Mogensen, Japan's Satoshi Furukawa and cosmonauts Konstantin Borisov, Oleg Kononenko and Nikolai Chub.

Meet the crew

Matthew Dominick served as Crew-8 commander on the journey to the ISS.

He was selected by Nasa in 2017 and this is his first spaceflight.

With a master's degree in systems engineering, the astronaut has also graduated from the US Naval Test Pilot School.

Michael Barratt was the pilot of the SpaceX capsule. He is on his third visit to the ISS and had already spent 212 days in space before this mission.

Selected by Nasa in 2000, Dr Barratt was flight engineer on a mission in 2009 and carried out two spacewalks. He also flew on the Discovery space shuttle in 2011.

Jeanette Epps was selected by Nasa in 2009 and this is her first spaceflight.

She has worked on other assignments with Nasa on the ground, including crew support astronaut for two missions and as lead capsule communicator in mission control, in Houston.

She was previously assigned to Nasa's Boeing Starliner-1 mission but was replaced so Boeing could have more time to complete development of the capsule.

Scientific research

Crew-8 is expected to carry out more than 200 experiments in science and research, technology development and commercialisation of low-Earth orbit.

Some of the work will involve using stem cells to create miniature versions of human organs to study degenerative diseases.

They will also analyse the effects of microgravity and ultraviolet radiation on plant cells.