Japanese astronaut Kimiya Yui and his crewmates underwent a two-day final examination through Thursday ahead of their May 27 trip to the International Space Station.

Yui, a 45-year-old flight engineer, commander Oleg Kononenko from the Russian Federal Space Agency and another flight engineer, Kjell Lindgren of NASA, took the exam in a full-size ISS simulator at a training center in the suburbs of Moscow.

During the test, the three astronauts checked various kinds of operational procedures, according to the Japan Aerospace Exploration Agency (JAXA) and other sources.

The crew is scheduled to blast off for the ISS on a Russian Soyuz spacecraft in the early hours of May 27 local time from Baikonur Cosmodrome in Kazakhstan and spend about six months on the ISS doing experiments.

However, the mission could be postponed in light of an unmanned cargo mission that failed on April 28, according to a report by Russian news agency Interfax.

"The flight program of the ISS expedition preparing for the mission may be adjusted depending on possible postponements of the dates of launches of cargo spacecraft and amendments to the ISS flight program," Interfax quoted a press release circulated at the training center as saying.

An expert at the Russian space agency has recommended that the launch to the ISS be pushed back by up to two months to focus on the investigation into the failed launch of the Progress M-27M spacecraft, which is now expected to burn up as it re-enters Earth's atmosphere, the report said.