The landing has been previously postponed several times to avoid early spring flooding on the Kazakh steppe.
"The landing capsule of the Soyuz TMA-9 spacecraft is expected to touch down at approximately 16.30 Moscow time (12.30 GMT) 133 kilometers (about 80 miles) southeast of the town of Dzhezkazgan in central Kazakhstan [on April 21]," the Federal Space Agency said in a statement.
The capsule will bring back to Earth U.S. astronaut Michael Lopez-Alegria and Russian cosmonaut Mikhail Tyurin of the 14th ISS Expedition, who began working at the world's sole orbital station on September 20, together with the fifth space tourist, Hungarian-born American software billionaire Charles Simonyi.
Simonyi, who is a trained pilot in multi-engine aircraft with current licenses in jets and helicopters and more than 2,000 hours of flying time under his belt, arrived at the International Space Station on April 10 together with the 15th ISS crew.
The new crew consists of Commander Fyodor Yurchikhin and Flight Engineer Oleg Kotov, both from Russia, who are scheduled to spend 189 days at the station and will conduct three spacewalks, one in U.S.-made spacesuits and the other two in Russian-made outfits.
The third crew member, U.S. astronaut Sunita Williams, who replaced the European Space Agency's German astronaut Thomas Reiter in December 2006, will stay on board the ISS for a further several months.
They will later be joined by astronaut Clayton Anderson, who will be launched aboard the Space Shuttle Endeavor June 28, and Daniel Tani, who will arrive with the Space Shuttle Discovery, scheduled for lift off September 7.
