MOSCOW (AP) — A Russian space capsule carrying a humanoid robot has failed to dock as planned with the International Space Station.

A statement from the Russian space agency Roscosmos said the failure to dock on Saturday was because of problems in the docking system, but didn't give details. It said the space station itself and the six-person crew are safe.

Roscosmos head Dmitry Rogozin said that another docking attempt will be made on Sunday, according to state news agency Tass.

The capsule was launched Thursday as part of tests of a new rocket that is expected to replace the Soyuz-FG next year.

It is carrying a robot called Fedor, which will perform two weeks of tests aboard the space station.