US
Russia's own orbital station will consist of three to seven modules unmanned or with a crew of two to four people
Russia's space agency says the loss will not affect the ISS system's normal operations
The crew is due to reach the station at 5:01 pm EST (2201 GMT) on Saturday
Ever wondered what it would be like to travel into space?
The three-man crew departed the station after spending half a year in Earth's orbit