Forty years after astronauts first walked on the moon, NASA, the US space agency, is officially committed to a $35 billion (£22 billion) plan instituted by President George W. Bush to build the first of a new generation of manned rockets that can return to the planet by 2020. However, the new president has appointed an independent panel to review America’s costly manned space programme, called Constellation, and make recommendations by the end of August. With NASA engineers now floating cut-rate rocket alternatives, some politicians and former astronauts fear that the 2020 deadline will be foiled by financial constraints.