sentences:  During the shuttle stand-down, construction of the ISS was halted and the science conducted aboard was limited due to the crew size of two, adding to earlier delays due to Shuttle problems and the Russian space agency's budget constraints.In March 2006, a meeting of the heads of the five participating space agencies accepted the new ISS construction schedule that planned to complete the ISS by 2010.As of May 2009, a crew of six has been established following 12 Shuttle construction flights after the second "Return to Flight" mission STS-121.