MOSCOW (Reuters) - Russia hopes the United States will extend the deadline to retire its space shuttles beyond 2011 and has heard unofficially it is possible, the head of Russia’s space agency was quoted as saying on Friday.

NASA's Space shuttle Discovery, atop a modified 747 carrier aircraft lift off from Edwards Air Force Base, California, September 20, 2009, en route to the Kennedy Space Center in Florida. REUTERS/Tom Tschida/NASA/Handout

The U.S. space agency NASA plans six more missions by its fleet of aging space shuttles by late next year or early 2011 after the construction of the $100 billion International Space Station (ISS) is completed. The shuttles will then be retired.

But the head of Roscosmos, Russia’s space agency, said he would prefer to see further shuttle missions to the Space Station, now in orbit 360 km (225 miles) above Earth.

“From some sources we have learned that it is possible to extend the life of the shuttle beyond 2011,” Roscosmos chief Anatoly Perminov was quoted by RIA news agency as saying. Reuters was not invited to the briefing.

“Then the situation would change substantially and it would be possible to work jointly with the Americans, unlike now, when the main burden (for the ISS) lies with the Russian side,” Perminov was quoted as saying by Interfax.

Perminov said he had not been told this through official channels, Interfax news agency reported.

He added that NASA’s new chief and former astronaut Charles Bolden would visit Russia’s Baikonur cosmodrome on September 30 in his first foreign trip.

NASA’s future strategy is currently under review with the main focus on possible flights to Mars. It is also encouraging a private space taxi project to the ISS. NASA’s current plan, conceived under former President George Bush after the Columbia accident, is to complete the space station, retire the shuttles and build new spaceships.

A new rocket and capsule to transport astronauts to the ISS is also being developed but will not be operational until about 2015. Until then, NASA will rely on Roscosmos and must pay $50 million per seat for flights to the ISS by Soyuz capsules.

The U.S., Russian and Chinese governments are the only entities currently capable of human orbital space flight, although several U.S. companies are developing vehicles and support services to do so.