MOSCOW (AP) — The return of two Russian cosmonauts and an American astronaut to Earth from the International Space Station that was scheduled for Friday has been pushed back by a day because of problems encountered while undocking, the head of the Russian space agency said.

The space fliers were told to return to the station from the Russian Soyuz capsule that was to carry them to a landing in the steppes of Kazakhstan, said Roscosmos head Anatoly Perminov.

American astronaut Tracy Caldwell-Dyson and Russia's Alexander Skvortsov and Mikhail Kornienko rejoined their three crewmates staying on board the space outpost. They were reported to be in good shape.

"The preliminary analysis, according to the technical commission, showed that a false signal appeared in the onboard computer system about the lack of a hermetic junction after closing the hatch on the station," Perminov said in comments shown on Russian state TV.

Perminov said the commission decided to reschedule the landing for Saturday. "It could be done today, but in order not to risk anything, we need reserve time," he said.

However, Rob Navias, a spokesman for the U.S. space agency NASA, said there were also problems opening hooks and latches on the space station side of the capsule.

NASA spokeswoman Kylie Clem, speaking from Mission Control in Houston, said later that the unlatching problem seems to have been solved. After the failed undocking attempt, one of the Russian cosmonauts on board, Fyodor Yurchikhin, inspected the space station docking mechanism holding the Soyuz in place and discovered a loose piece of gear mechanism with two teeth broken off.

The crew installed a series of electrical jumper cables to bypass what's believed to be a failed part. Once that was completed, the cosmonauts performed a test, and the hooks and latches opened properly, Clem said.

The hooks and latches that failed to operate properly Thursday are located on the Russian Poisk (Exploration) docking compartment, which was launched by a space shuttle last November. The failed part apparently prevented commands from being received by the docking mechanism on the space station side.

Friday's incident was the second problem in three months with docking or undocking Russian craft at the space station.

In July, an unmanned Progress supply ship failed to dock because of the activation of a transmitter for the manual rendezvous system, which overrode the automated system.

After the failed docking, it was moved to about 180 miles (300 kilometers) from the station. A second docking attempt succeeded two days later.


Associated Press writers Marcia Dunn in Cape Canaveral and Peter Leonard in Almaty, Kazakhstan, contributed to this report.