The International Space Station
The biggest story of the next decade
It is the largest scientific project in history and the biggest space story of the next decade. The International Space Station (ISS), orbiting above the atmosphere, will provide a platform for telescopes. This means that experiments can be built and implemented rapidly, and equipment can be replaced easily with new technology.
The ISS, however, is not primarily an observatory. It will be used to study how astronauts are affected by long-term weightlessness, acting as a testbed for projects such as a voyage to Mars.
Scientists will also be able to study how crystals grow, flames burn and fluids flow without the warping effect of gravity.
Success depends on overcoming the problems of building such a vast structure. It will take 45 assembly missions to complete the ISS, each one with its own risks. When complete the ISS will then have to be wary of 23,000 objects larger than a cricket ball and each orbiting at 30,000km an hour. More than Pounds 3 billion has been spent on shielding to protect the ISS.
Almost as frightening are the political problems. Nasa fears that the Russians may fall behind schedule or cut costs at the expense of safety.
The launch of the Russian Zvedza module (ISS living quarters) was partly funded by Pizza Hut, which paid $1 million to have a logo on the side of the rocket. With a few more such deals, the ISS should be complete by 2005.
The Next Generation Space Telescope
Mission: explore when galaxies began to form
As the Hubble Space Telescope enters the latter half of its life, there are plans to replace it with the Next Generation Space Telescope, a joint Nasa-European Space Agency project to be launched in 2007.
Its main objective will be to explore the period when galaxies began to form, which will mean detecting ancient, and therefore very distant, objects.
The Big Bang model states that the light from distant objects will have been stretched by the expansion of the universe. This results in a "reddening" in the colour of emitted light. If the object is far enough away, the light will be predominantly infrared, so the NGST will be an infrared telescope.
One of the problems it has to overcome is temperature. Because hot objects emit infrared light, the NGST must be cold, otherwise its emissions would confuse the detector. The instruments on board will be cooled to -240C.
To distance the telescope from terrestrial sources of infrared radiation, it will be parked 1.5 million km from the Earth. Furthermore, it will be protected from the Sun's radiation by a shade the size of a tennis court, a remarkable achievement given that the NGST will be launched inside a rocket that is less than 6m in diameter.