The aim of the International Space Station, which orbits high above Earth, is to provide a scientific environment to conduct experiments that are simply not possible on Earth. Aboard the ISS, which is still under construction, the effects of gravity are effectively removed. This 'microgravity' has wide-ranging results on everything, from the behaviour of liquids to the dynamics of combustion. There is ongoing research into these issues.

The microgravity environment of the space station could also help advancements in biomedical research – which could have important consequences for fighting age-related diseases such as osteoporosis - and improving medical techniques against the spread of viruses like HIV. At 200 miles (322 kilometres) above Earth, the ISS also provides an unrivalled platform from which to observe weather patterns on our own planet and survey the universe. So far, three space tourists have paid multi-million dollar fees to travel to the ISS aboard Russian rockets.

The US space shuttle programme has effectively been on hold since the 2003 Columbia disaster. Apart from the shuttle Discovery's summer 2005 mission, the only link between the ISS and Earth has been via Russian Soyuz capsules. Although 16 countries funded the building of the ISS, Russian officials claim that they have been taking most of the responsibility for keeping the space station going and have been delivering supplies to the ISS single-handedly.

The first manned ISS mission since the Columbia accident was launched on 26th April 2003. Expedition Seven – Russian cosmonaut Yuri Malenchenko and US astronaut Ed Lu – took over from the three-man team who – due to the shuttle disaster - had been forced to stay an extra two months up on the ISS since their arrival in November 2002. In fact, in August 2003, Malenchenko became the first man ever to marry in space. Yuri and his girlfriend tied the knot by video link between the ISS and the Nasa space control centre in Houston, Texas!

The shuttle Discovery's 2005 mission to take parts and supplies to the ISS did not go entirely as planned. On the first shuttle flight since the Columbia disaster, cameras monitoring the lift-off detected foam flying from the external fuel tank and hitting the underside of the shuttle. NASA engineers were concerned because they believe a foam-damaged wing caused Columbia to break up as it re-entered the Earth's atmosphere.

Discovery's crew of seven astronauts made temporary repairs to the shuttle in orbit and landed safely.