Space exploration provides glaring examples of errors in the exploitation of technology, even where the most stringent criteria apply. In the late 1960s the three stages of a European rocket were successfully constructed but could not be assembled because the French and German stages were based on metric units, whereas the UK stage was based on imperial units. The air conditioning failed on an early space station resulting in a deeply foetid atmosphere with mould growing on the wall. A Challenger mission terminated disastrously because of faulty testing and reporting procedures concerning sealant O-rings. A European satellite failed in 1989 because it contained a motor which had not been tested in vacuum, since the manufacturer had not been informed it was to be used in space. In the same year the solar panels on another satellite moved in the wrong direction because they had been wired the wrong way round. Apollo 13 was forced to make an early return because a heater switch had been accidentally welded into an on position causing the tanks to blow up. The Hubble telescope launched into space contained a mirror which had not been adequately tested resulting in out of focus pictures and necessitating a costly repair mission. In 1993 the blueprints for the Saturn V booster could no longer be located. In the same year controllers lost contact with a Mars probe because of delays in a corrective procedure which resulted in valves not working under the altered conditions for which they had not been tested.