Asked by: Michael Turner, Pontefract
The first component of the International Space Station (ISS) was launched in 1998, and the final piece is due to be added in 2010. When it's finished, the ISS will have a mass of nearly 420,000kg and be four times as big as the deceased Russian space station Mir. Perhaps, like Mir, the ISS will outlive its life expectancy. Each ISS module has a planned lifetime of 10 years; by that reckoning, the entire space station will need replacing by 2020. That said, the ISS has an ongoing programme of maintenance and renewal - so I reckon it should keep going for at least another 15 to 20 years.
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