ISS maintenance. Astronaut Susan J. Helms carrying out battery maintenance beneath the floor of the Zarya module of the International Space Station (ISS). As seen on the walls, every instrument used needs to be firmly secured in the weightless environment of space. Helms and her colleagues worked on the interior and exterior of the ISS during mission STS-101 (19th-29th May 2000). They flew there on the Space Shuttle Atlantis. The ISS is a joint effort between NASA, the European Space Agency, the Russian space agency, Canada, Japan and Brazil. It orbits at an altitude of 350 kilometres and will be over 100 metres in length. It is scheduled for completion in 2004.