Crew

• Vladimir Kovalyonok (1)
• Valery Ryumin (1)

Mission Parameters

• Mass: 6860 kg
• Perigee: 198.5 km
• Apogee: 258.1 km
• Inclination: 51.66°
• Period: 88.66 minutes

Soyuz 25 was a Soviet human spaceflight launched October 9, 1977. It was meant to be the first mission to the Salyut 6 space station but failed after a problem with the docking system. On board were Vladimir Kovalyonok and Valery Ryumin. Their callsign for the mission was Foton (Photon).

All went well right up until docking. But for some reason the spacecraft would just not hard dock. Or as the news release stated:

• "At 07.09 Moscow time today (10 October, 1977) the automatic rendezvous of the Soyuz 25 ship and the Salyut 6 station was begun. From a distance of 120 metres, the vehicles performed a docking manoeuvre. Due to deviations from the planned procedure for docking, the link-up was called off. The crew has begun making preparations for a return to Earth."

The hard docking was needed for the enabling of electrical connections. The spacecraft then retracted itself and formed a tight seal. The problem was traced later to a faulty mechanism on the Soyuz but this was not discovered until after the Soyuz 26 flight, who performed an EVA to inspect the second docking port on Salyut 6. Because the crew were flying the Soyuz 7K-T spacecraft there was only battery power available for a short two day mission. The crew were forced to re-enter and landed 185 km northwest of Tselinograd, Kazakhstan.

This failure resulted in a rule stating that crews had to have at least one crew member who had flown before. This resulted in the all-rookie backup crew of Aleksandr Ivanchenkov and Yuri Romanenko being paired with veteran cosmonauts for later missions.