Their return caps a protracted space mission that was fraught with uncertainty and technical troubles and turned a rare instance of NASA's contingency planning - and the latest failures of Boeing's Starliner - into a global spectacle.

The first astronauts to fly on two different commercial spacecraft during a single mission, Suni Williams and Butch Wilmore, returned to Earth with ISS crewmates Nick Hague and Aleksandr Gorbunov.

Astronauts Sunita Williams and Butch Wilmore required health checks after returning to Earth following their nine-month stay on the International Space Station (ISS)