Since the launch of core module on February 20, 1986, till March, 23, 2001 Mir Orbital Complex (Mir OC) was in operational use on orbit under the Flight Test Program of the module-based permanently manned Mir station. A total of more than 100 launches of different spacecraft and modules (including the US Shuttle launches) were performed under the Mir Complex Mission Program. In spite of some remarks made, all the launches were successful with a 100% fulfilment of the main flight tasks.
One of the Mir OC Mission Program features lay in the fact that upon orbital insertion of the core module there was a relatively long period scheduled to resupply the Complex through adding new modules to it and building up technical capabilities of the onboard systems. In an initial stage of the Mir OC operation its operational use could be provided only in a visiting mode, while its use as the permanently operating station was limited for lack of the required MCS and LSS aids.
From March 15, 1986 through May 5, 1986 the first manned flight to the Mir OC (Prime Crew 1) was carried out. In the first flight phase the activities were conducted under the Salyut and Mir Mission Program for 1986 and 1987, which was completed in December, 1987 following the launch of the Soyuz TM-4 space vehicle (Prime Crew 3).
Operation of the Mir OC permanently flying on orbit started on February 8, 1987 (Prime Crew 2).
During 1986-1987 the Complex was resupplied as scheduled with the control systems (OCS Salyut-5B, CICC gyrodines) and life support systems (Vozdukh, Elektron-V systems, MIU, etc.) to change over to its continuous manned operational use.
The Complex was deployed until it reached its final configuration on April 26, 1996 after the Priroda Module had been docked. This event marked the completion of the "Flight Test Program of the permanently Operating Manned Module - Based Mir Station". Further the Complex operated on an annually scheduled mission program. In addition to the modules envisaged by the abovementioned Program, Docking Module (DM) was incorporated in the Complex on November 25, 1995 to conduct the activities with Shuttle involved.
Before August 1999 came, the Mir OC had been operated as a permanently flying station, except for one time interval from April 27 till September 8, 1989, when there had been a changeover from the Soyuz T manned space vehicles to the Soyuz TM space vehicles.
From mid-1999, due to being faced with the difficulties in financing the Mir OC Mission Program, the Compex operational conditions were changed by incorporating in the Program of relatively long unmanned phases for economy reasons.
Having flown many years in manned conditions, the Mir OC was shifted to unmanned flight conditions for the first time on August 28, 1999.
As the use of control mode (OCS + gyrodines) in the absence of crew might result in a reduced control reliability, prior to changing over to the Mir OC unmanned flight a backup analog control loop was introduced and tested, which made it possible to fulfill the following tasks without MCS OCS involved:

• Inertial stabilization;
• Angular velocity damping;
• Complex spinning relative to core module X and Y axes;
• Arriving at status vector of the Mir Complex by TMI data of the Kvant Module SM-8M magnetometer or the Kvant-2 Module OSS star sensor.

Analog loop ensured control capability of the Complex by uplink commands when the OCS Failure commands pass.
Throughout its unmanned flight phase the Mir OC was operated with OCS off and maintained passive attitude control for storage batteries additional charging.
Maintenance of the required orbital altitude in this phase to prevent the Complex from deorbiting due its natural atmospheric braking was provided by generation of corrective impulses by the Progress vehicles operating as part of the Complex.