ISS becomes crowded
The combined crew will perform a range of experiments, including research to help develop new anti-cancer medicines. Some of the experiments are to be held for the first time in space.
During their stay, the astronauts will be visited by the American space shuttle Atlantis, which will be delivering supplies. That will be the very last mission of a NASA shuttle, as the fleet is being grounded.
Among the other planned activities they have is receiving three Progress cargo crafts and the installation of new equipment for laser communications.
The trio will stay on the ISS for five months, until the middle of November.