The Japanese Aerospace Exploration Agency (JAXA) is mulling the conversion of its expendable H-2A Transfer Vehicle (HTV) space freighter into an astronaut transport, the agency’s top official said in an interview posted Feb. 7 on JAXA’s website.

“Now that the Space Shuttle has been retired, our only way to send astronauts to the [international space station] is the Russian Soyuz spacecraft, so if the Soyuz has an accident then we’ll have no means of transporting astronauts at all,” JAXA president Keiji Tachikawa said. “As we discuss how to secure transportation redundancy, people are looking to Japan’s KOUNOTORI space-station supply ship,” which could be converted to carry astronaut crews, he said.

As a preliminary step, JAXA would have to develop a reusable variant of the HTV, an effort that would take about five years, Tachikawa said.

The existing HTV design, which can deliver up to 6 tons of cargo to the international space station, has flown in space twice. The third launch is scheduled for late June, but Japanese media reports, citing a public address by Tachikawa Feb. 9, said that fallout from a contract scandal with Mitsubishi Electric Corp. might delay the mission. The company, Japan’s biggest satellite builder, recently admitted overcharging the government on military and civil space contracts.

JAXA officials could not be reached for comment by press time.