Part of the show Naked Science Q&A and Polonium Poisoning
The fifth and probably final service mission to the Hubble Space Telescope has been approved to keep it running to around 2013. Hubble was designed so that astronauts could visit the telescope to make repairs and swap old instruments for new updated versions. However, the latest mission scheduled for 2004 was cancelled after the Columbia shuttle was destroyed on re-entry. Now that recent shuttle missions have performed well it is thought that it is safe to send astronauts to Hubble again, however because Hubble is farther from the Earth than the space station, it is unlikely that a rescue mission could be launched if there is a problem with the shuttle. The mission itself will concentrate on replacing gyroscopes and batteries and adding two new instruments. The gyroscopes are spinning weights that keep Hubble stable and three are required. Hubble has six in total with three being spares. Currently two are too worn to use so only one spare is left. Batteries also have finite lifetime as anyone out there with a mobile phone will know. A new phone will stay charged for days but an old one may only last hours. Hubble's batteries are now 16 years old so they don't charge up from the solar panels very well any more. The new instuments are called the wide field camera 3 and the cosmic origins spectrograph. The wide field camera is essentially a new updated digital camera with a 16 megapixel CCD sensitive not only to visible light but also to UV and also an infra red detector. The spectrograph is built to look specifically at long strands of galaxies that have previously been discovered separated from each other by vast voids of empty space. The new improved Hubble should then last until at least 2013, by which time the new James Web telescope should have been launched into space to take over.