AKA: Foton (Photon). Launched: 1977-10-09. Returned: 1977-10-11. Number crew: 2 . Duration: 2.03 days.

Recovered October 11, 1977 3:25 GMT.

Narrative (adapted from D S F Portree's Mir Hardware Heritage, NASA RP-1357, 1995)

Soyuz 25 achieved soft dock with the new Salyut 6 station, inserting its probe apparatus into the conical drogue of the Salyut 6 front port. Hard docking involved retracting the probe to pull the station and spacecraft docking collars together. However, the docking collars would not latch. Cosmonauts Vladimir Kovalyonok and Valeri Ryumin had to return to Earth before their ferry's batteries became depleted. Engineers theorized that the Salyut 6 forward port might have been damaged during ascent, or that the Soyuz 25 docking unit was at fault. If the latter was true (and they could not be certain, because the docking unit was discarded before reentry, along with the Soyuz 25 orbital module), then it was possible that the several hard docking attempts had damaged the Salyut 6 forward port, making it unfit for future dockings.

• Soyuz 25 - . Call Sign: Foton (Photon). Crew: Kovalyonok, Ryumin. Backup Crew: Ivanchenkov, Romanenko. Payload: Soyuz 7K-T s/n 42. Mass: 6,860 kg (15,120 lb). Nation: Russia. Agency: MOM. Program: Salyut 6. Class: Manned. Type: Manned spacecraft. Flight: Soyuz 25. Spacecraft Bus: Soyuz. Spacecraft: Soyuz 7K-T. Duration: 2.03 days. Decay Date: 1977-10-11 . USAF Sat Cat: 10401 . COSPAR: 1977-099A. Apogee: 240 km (140 mi). Perigee: 194 km (120 mi). Inclination: 51.60 deg. Period: 88.80 min. Manned two crew. Unsuccessful mission. Failed to dock with Salyut 6..

• Landing of Soyuz 25 - . Return Crew: Kovalyonok, Ryumin. Nation: Russia. Related Persons: Kovalyonok, Ryumin. Program: Salyut 6. Flight: Soyuz 25. Soyuz 25 landed at 03:24 GMT. .