KOROLYOV, March 28. /ITAR-TASS/. The failure of Soyuz TMA-12M software, which postponed the docking for two days, was caused by rare conjuncture, chief mission controller Vladimir Solovyov told reporters after the successful docking of the spacecraft with the International Space Station on Friday.

It was very rare conjuncture ballistic, light and shadow, work of certain sensors, speed, a very low impulse and narrow turning angles, he said. It caused the failure. To avoid risks, a decision was made for the longer flight scheme for the docking.

Smooth and precise work of all the onboard and ground systems is needed for a short-time docking operation, he noted. When a spacecraft flies to the station fast, it is a very tight scheme with only three-five minutes to analyze the situation.

In this case, after a series of dynamic operations, the orientation system malfunctioned, and at some moment, the Soyuz was not orientated as needed, Solovyov explained. The situation could be corrected, but on manned missions, safety and reliability are taken into consideration first of all.

When the shorter flight scheme was worked out, a reserve two-day operation was envisaged, he said. When the problem emerged, the controllers decided to switch to the two-day flight to analyze everything calmly, he said. The longer scheme gives reserve 24 hours to analyze the situation and spend less fuel, he explains.

Commenting on the docking, Solovyov noted the operation was carried out as planned. Everything was done automatically, without problems with spacecraft systems, the work of the Mission Control Center and the work of cosmonauts, he noted.

No doubts were about the good operation of the onboard computer. There was no need to change the software, he said.

Next manned Soyuz flights will be carried out according to the short-time scheme, but some corrections may be made to the software. "Maybe something will be added to remain in the memory of the onboard computer just in case," Solovyov said.

The crew felt well. Everything was proceeding as planned, he told reporters in conclusion.