O'Keefe was due to leave Washington late Friday, NASA spokesman Bob Jacobs said.

On Sunday, he will welcome the three-man crew to Earth upon their return from the ISS, aboard a a Russian Soyuz capsule.

US astronauts Kenneth Bowersox and Donald Pettit and Russian cosmonaut Nikolai Budarin have been on the ISS since December. They were to have left in March, but their return to Earth was delayed because of the Columbia space shuttle disaster.

Columbia disintegrated during re-entry to the Earth's atmosphere on February 1, killing all seven crew members and leading NASA to suspend all shuttle missions, including those to the ISS.

Russian spacecraft now provide the only transportation to the space station.

O'Keefe will also meet with Yuri Koptev, his counterpart at the Russian space agency Rosaviakosmos, Jacobs said. He gave no details of the expected nature of their talks.

SPACE.WIRE