The ISS project is a partnership of five - the US, Russia, Europe, Japan and Canada. At the moment, no program for its use nor any money has been put in place to support the platform beyond 2015. One of the biggest issues stopping an agreement on station-life extension  is the human spaceflight examination ordered by US President Barack Obama. The Americans are developing a new vision for space exploration, and the rockets and spacecraft they will need to start it. The future of US joining in the ISS is closely tied to the result of the examination. Mr Dordain, the European Space Agency's (Esa) Director General, said no one partner in the ISS project could alone call an end to the platform. A meeting would be held in Japan later in the year where he hoped the partners could get something clearly going forward. He said it was also necessary the benefits  were increased and the costs were reduced. Increasing the benefits could include finding new uses for the station. Esa has called for ideas on how to use the ISS as a platform for Earth observation . Mr Dordain said the agency had received about 20 very good proposals. On the issue of reducing costs, there were many ideas on the table, he explained. He also questioned whether it was necessary for the station to have six astronauts at all times. If there were periods when little maintenance  was required or the experiment load was light, could the ISS run on a smaller group of people, he suggested. Construction of the space station should finish this year. Next month, two _ s built in Europe - a connecting node and a robotic control room - will be flown to the platform by the US shuttle Endeavour. Tranquility and the Cupola, as they are known, will complete the non-Russian side of the ISS. Why will America joining in the ISS be tied to the result of the examination?
Because America is the greatest power among them Because America provides most of the money Because they need America's rockets and spacecraft Because Obama ordered the human spaceflight examination