nce it is completed. To stay in orbit, a docked Progress rocket, Shuttle, or the Zarya module will fire its engines, increasing the ISS's orbital speed, and therefore, its orbital height.
Currently, Congress has approved five years of funding for ISS development and construction, about $24 billion, and a 10-yr operating budget of $13 billion. NASA expects the station to have a much longer life than the current 10-yr plan. After all, many ISS parts were originally designed for the all-American Freedom space station and a 30-yr life. NASA was instructed to use as many Freedom components and modules as they could. All station components are also designed for transport and assembly in space, so almost anything can be replaced.
ISS's extended life is not hard to accept when you consider that Pioneer 10, a mission launched 29 years ago and formally ended four years ago, is still functioning. Signals from Pioneer were detected last April when it was about 7.3 billion miles from the Earth traveling 27,830 mph. So it's likely the ISS will outlive its budget.
When the end finally comes, the ISS will be "decommissioned" by taking it apart into pieces sized to burn up on reentry and then sending them Earthward.