The U.S. shuttle Atlantis will undock for the last time from the International Space Station on Tuesday, NASA said.
The undocking of the spacecraft from the station's module Harmony is set for 10:28 Moscow time (6:28 GMT) and the shuttle is expected to land in Florida on July 21.
Once the U.S. shuttle fleet is retired after the end of the current Atlantis mission to the orbital station, Russia's Soyuz and Progress spacecraft will take the bulk of crew rotation and cargo missions to the ISS until at least the middle of the decade.
Russia has signed a number of contracts with NASA on the delivery of U.S. astronauts to the ISS until 2016, which take into consideration annual inflation rates and rising cost of materials in Russia.
NASA is paying Roscosmos more than $1 billion for crew transport services over the next four years.
