Launch

Soyuz TM-5 launched on 1988 June 7 and arrived at Mir on June 9 carrying the second Bulgarian in space, Alexandrov (not to be confused with the Soviet cosmonaut of the same name). He became the first Bulgarian to reach a Soviet space station (Georgi Ivanov failed to reach Salyut 6

Salyut 6

Salyut 6 , DOS-5, was a Soviet orbital space station, the eighth flown as part of the Salyut programme. Launched on 29 September 1977 by a Proton rocket, the station was the first of the 'second-generation' type of space station. Salyut 6 possessed several revolutionary advances over the earlier...

 on Soyuz 33

Soyuz 33

-Backup crew:-Mission parameters:*Mass: *Perigee: *Apogee: *Inclination: 51.63°*Period: 88.99 minutes-Mission highlights:...

 in 1979—Alexandrov was his backup). Their launch had been advanced by 2 weeks late in the planning stages to improve lighting conditions for the Rozhen astronomical experiment.

Landing

On September 5 cosmonauts Lyakhov and Mohmand undocked from Mir. They jettisoned the orbital module

Orbital module

The orbital module is a portion of spacecraft used only in orbit. These have developed from the Soviet Soyuz spacecraft.-Soyuz orbit module:The orbit module is a spherical part of Soviet-Russian Soyuz space ship series...

 and made ready for deorbit burn

Orbital maneuver

In spaceflight, an orbital maneuver is the use of propulsion systems to change the orbit of a spacecraft.For spacecraft far from Earth—for example those in orbits around the Sun—an orbital maneuver is called a deep-space maneuver .-delta-v:...

to return to Earth. During descent, the spacecraft experienced a computer software problem combined with a sensor problem. This caused their landing to be delayed by a full day. The Descent Module, where they spent this 24 hour period, had no sanitary facilities. They would not have been able to redock with Mir because they had discarded the docking system along with the orbital module. Reentry occurred as normal on September 7. Following this incident, the Soviets decided that on future missions, they would retain the orbital module until after deorbit burn, as they had done on the Soyuz Ferry flights.