Just when the two residents of the International Space Station thought it was safe to be there, new problems arrived. Or should we say, old problems? The oxygen generator, which had broken down last fall, failed once again on Saturday. This problem comes just over one week after a Russian resupply ship was able to replenish the diminishing supply of food on the station.

The oxygen generator was built by the Russians and has been repeatedly patched. The problem appears to be the same as it was before: gas bubbles in the machine's extensive network of pipes.

American astronaut Leroy Chiao and Russian cosmonaut Salizhan Sharipov worked together to try to make repairs. Meanwhile, air was replenished Tuesday by the same supply ship that brought food to the station on Christmas day.

According to a NASA spokesman, Chiao and Sharipov are in no immediate danger as there is a large supply of reserve oxygen available to them at the space station. The question remains, will things ever run smoothely up there?