Russia says it will suspend short term and tourist visits to the International Space Station in order to focus on delivering replacement crews and fresh supplies to the outpost.
With NASA's decision to ground U-S space shuttle flights following the Columbia disaster, the Russian space program must take over responsibility for support of the station.
The station's current crew of two American astronauts and one Russian cosmonaut is scheduled to be replaced in March. But Russian officials say it may be April before a fresh crew can arrive aboard a Russian Soyuz spaceship.
On Monday former President Bush and his wife Barbara spoke to the astronauts on the station from mission control about the Columbia disaster.
Russia launched an unmanned Progress cargo ship to the I-S-S on Sunday. The Progress is to dock with the station Tuesday with enough supplies to last the crew until June.
The International Space Station project involves 19 countries, but Russia and the United States are the only two capable of sending supplies and crews into space.