Russian officials say that an unmanned Russian cargo spacecraft failed to dock with the International Space Station early morning due to a technical failure.
Russian Mission Control said on Tuesday that the spacecraft will attempt the docking on Sunday.
The Progress cargo ship separated from the station Sunday to perform engineering tests and try out a new docking system.
There are currently six people on the Space Station: three Russians, two Americans and a Japanese astronaut.
Russia's Mission Control did not name the specific cause of the failure, but said they are looking into it.