L-R) Russia's Alexander Grebenkin and NASA astronauts Michael Barratt, Matthew Dominick and Jeanette Epps (Picture: AP)
(L-R) Russia’s Alexander Grebenkin and NASA astronauts Michael Barratt, Matthew Dominick and Jeanette Epps (Picture: AP)

A NASA astronaut was flown to a hospital after returning to Earth with what the US space agency described as an unspecified medical condition.

Three NASA astronauts and a fourth from the Russian space agency spent almost eight months at the International Space Station after their homecoming had been stalled by problems with the Starliner capsule.

The crew splashed down off Florida’s coast at 7.29am on Friday aboard SpaceX’s Crew Dragon.

The astronaut, who NASA did not name for privacy reasons, is understood to be suffering from a medical issue, but the agency did not disclose what it is as of yet.

NASA initially said the entire crew was flown to Ascension Sacred Heart Pensacola hospital out of precaution, but did not specify whether all or some of them had been experiencing issues.

The other three crew members have left the hospital and returned to Houston, the space agency said.

SpaceX launched the four personnel – Nasa’s Matthew Dominick, Michael Barratt and Jeanette Epps, and Russia’s Alexander Grebenkin – in March.