Early on the morning of Feb. 1 the US space agency NASA's space shuttle Columbia tore apart in the outer reaches of Earth's atmosphere, killing all seven astronauts on board. Last month the heads of the world's leading space agencies met for the first time since the disaster to discuss the future of the International Space Station (ISS). Given the grounding of the shuttle fleet, the space station appeared to be in a precarious position. But the truth was there was little to discuss: the shuttle had to be forced back into service or the space station would remain a half-finished millstone around NASA's neck. Now, after the report by the Columbia Accident Investigation Board (CAIB) at the end of last month, NASA knows what it must do to get the shuttle fleet back into operation. But the report did not address internal divisions at NASA. Some within the agency believe the Columbia accident can be all but shrugged off; that the shuttle can be made to fly for another 20 years if need be. Others say enough is enough: the ageing shuttle is past it. It's time for something new. There's no doubt the shuttle will be put back in service in the short term. It has to be. Many of the remaining modules that are due to be fitted to the international space station have been finished or are nearing completion.