# Soyuz T-15

> first and only crewed spaceflight to travel between two space stations in one mission

**Wikidata**: [Q841796](https://www.wikidata.org/wiki/Q841796)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Soyuz_T-15)  
**Source**: https://4ort.xyz/entity/soyuz-t-15

## Summary
Soyuz T-15 is the only crewed spaceflight in history that visited two different space stations—Mir and Salyut 7—during a single mission. Launched by the Soviet Union on 13 March 1986, it ferried the first long-duration crew to Mir, then flew to the abandoned Salyut 7 to retrieve equipment before returning to Mir for the mission’s end.

## Key Facts
- Only mission to transfer crew between two separate space stations (Mir and Salyut 7) in one flight.
- Launched 13 March 1986 at 13:33 UTC from Baikonur Cosmodrome Site 1 (Gagarin’s Start) aboard Soyuz-U2.
- Landed 16 July 1986 at 12:34 UTC in Kazakhstan after 125 days 0 hours 56 minutes in orbit.
- Crew: Leonid Kizim (Commander) and Vladimir Solovyov (Flight Engineer).
- Spacecraft: Soyuz-T 11F732 #15; launch mass 6 850 kg.
- Orbit: 331 km × 366 km, 51.6° inclination, 91.5 min period; 1 980 orbits completed.
- Docked with Mir 15 March–5 May 1986; Salyut 7 6 May–25 June 1986; Mir again 26 June–16 July 1986.
- COSPAR ID: 1986-022A; NSSDC ID: 16643.
- Call sign “Mayak”; backup crew Aleksandr Viktorenko / Aleksandr Aleksandrov.
- Part of the Soviet Soyuz programme; followed Soyuz T-14 and preceded Soyuz TM-2.

## FAQs
### Q: Why did Soyuz T-15 fly to two stations?
A: After delivering Mir’s first resident crew, the Soviets wanted to salvage valuable hardware from the derelict Salyut 7. Soyuz T-15 was the only craft fitted for the risky 2 000 km orbital plane change, so it flew to Salyut 7, stripped equipment, then returned to Mir.

### Q: How long did the crew stay on each station?
A: 51 days on Mir (15 Mar–5 May), 50 days on Salyut 7 (6 May–25 Jun), and 20 final days on Mir (26 Jun–16 Jul).

### Q: Was the mission successful?
A: Yes. All dockings, spacewalks, and equipment transfers were completed, proving dual-station operations and setting endurance records for the Soyuz-T variant.

## Why It Matters
Soyuz T-15 closed the Soviet Union’s first space-station era while opening the next. By bridging Mir and Salyut 7, it demonstrated precision orbital rendezvous across vastly different planes, validated heavy-lift manual cargo return, and preserved priceless solar-array panels and instruments that later flew on Mir modules. The mission proved a single crew and spacecraft could service multiple orbital platforms—an operational concept that underpins today’s plans for lunar gateways and commercial free-flyers. Politically, it showcased Soviet continuity between the aging Salyut programme and the new Mir complex just weeks after the Challenger disaster, reinforcing USSR leadership in long-duration spaceflight. Technically, the 2 000 km orbital hop remains unmatched by any subsequent crewed craft, making T-15 a singular feat of astrodynamics and mission design.

## Notable For
- Only crewed flight ever to relocate between two distinct space stations.
- Longest Soyuz-T mission (125 days) and the only one to exceed 100 days.
- First spacecraft to dock with Mir, undock, redock elsewhere, then redock with Mir again.
- Executed the largest crewed orbital plane-change maneuver (≈2 000 km) to reach Salyut 7.
- Retrieved 400 kg of equipment from Salyut 7, including the first space-flown solar array later reused on Mir.

## Body
### Mission Architecture
Soyuz T-15 used the upgraded Soyuz-T spacecraft (11F732 variant) with new Kurs rendezvous radar and solar-panel capability for extended missions. Launch mass was 6 850 kg, including 2 000 kg of propellant for the unusual plane-change burn. The craft carried the standard spherical re-entry module, cylindrical orbital module, and cylindrical service module with twin solar arrays.

### Flight Profile
13 Mar 1986: Liftoff at 13:33:10 UTC; inserted into 51.6°, 331 × 366 km orbit.
15 Mar 1986: Automated docking with Mir’s front port; crew became Mir EO-1.
5 May 1986: Undocked from Mir; performed two-day free flight while ground teams computed Salyut 7 intercept.
7 May 1986: Fired main engine twice to raise apogee and shift orbital plane 2 000 km west.
8 May 1986: Manual docking with Salyut 7; crew conducted five internal transfers and two EVAs (20 May, 23 May) to remove two 60 kg solar-array cassettes.
25 Jun 1986: Undocked from Salyut 7; re-rendezvoused with Mir 26 Jun.
16 Jul 1986: Descent module touched down 55 km northeast of Arkalyk at 12:34 UTC.

### Crew Activities
Kizim and Solovyov logged 125 days in space, performed 31 scientific experiments, and operated the first Mir gyrodyne attitude-control system. During Salyut 7 stay they reactivated the station’s life-support loop, proving dormant-module reactivation techniques later used on Mir and ISS.

### Legacy Hardware
Retrieved solar-array cassettes were refurbished and installed on Mir’s Kvant-2 module in 1989, adding 2 kW of power. The mission’s flight plan and propellant margins informed design of the Progress-M tanker and the Soyuz-TM series.

## References

1. Jonathan's Space Report
2. Freebase Data Dumps. 2013
3. [Source](http://www.spacefacts.de/mission/english/soyuz-t-15.htm)
4. BabelNet