Soyuz TMA-12M is a 2014 flight to the International Space Station. It transported three members of the Expedition 39 crew to the International Space Station. TMA-12M is the 121st flight of a Soyuz spacecraft since the first in 1967 and the 38th Soyuz mission to the ISS. The Soyuz is to remain docked to the space station to serve as an emergency escape vehicle until TMA-12M's scheduled return to Earth in September 2014.

After a successful launch on 25 March 2014, docking was scheduled to occur on 26 March via the relatively new six-hour duration orbital trajectory. In the event, one of the orbital burns scheduled to refine the trajectory did not occur as planned, due to an attitude control problem in which the spacecraft was incorrectly oriented. The rendezvous phase was subsequently replanned to the formerly-used two-day trajectory. Accordingly, TMA-12M arrived at the ISS on 27 March.

The Soyuz TMA-12M used a four-orbit, six-hour flight profile to reach the station. The docking at the Poisk module was scheduled at 11:04 p.m. EDT on March 25. However the spacecraft was unable to complete its third thruster burn to fine-tune its approach, requiring to postpone the docking until March 27.

According to NASA, flight controllers in Moscow were reviewing data to determine the reason the third thruster burn did not occur. In conversations between flight controllers in Moscow and Houston, initial information indicated the problem may have been the spacecraft was not in the proper attitude, or orientation, for the burn, NASA said.

According to NASA, flight controllers in the Mission Control Center outside Moscow reverted to a backup 34-orbit rendezvous, which would result in an arrival and docking at 7:58 p.m. Thursday, March 27 (March 28 Moscow Time). Rendezvous experts were reviewing the plan, and may update it later as necessary, NASA said.
At the station, the fresh crew will join Expedition 39 Commander Koichi Wakata and Flight Engineers Rick Mastracchio and Mikhail Tyurin.

On March 26, a poster on the online forum of the Novosti Kosmonavtiki magazine reported that the problem during the initial rendezvous attempt resulted from a slightly higher initial orbit, where the launch vehicle had left the spacecraft after completing the orbital insertion. Even though such deviations are relatively frequent and the latest 20-kilometer increase in apogee was within allowable limits, it apparently confused computers onboard Soyuz TMA-12M. The first two orbit corrections of the spacecraft were performed as programmed on the ground, however the third and fourth firings were supposed to be calculated by the onboard TsVM-101 computer and correct possible errors in the orbital insertion. As a result of higher-than-expected-orbit, these maneuvers had to be extremely short. As a result, the computer decided to perform these firings with small orientation thrusters, DPO, instead of main orbit-correction engines, SKD. According to one scenario, this switch caused some sort of problem in the flight control system.

Soyuz TMA-12M successfully docked to the MIM2 Poisk module in automated mode on March 28, 2014, at 03:53:33 Moscow Time. The crew then transferred onboard the outpost at 06:34 Moscow Time, Roskosmos announced.

Soyuz TMA-12M lands successfully
Three out of six members of the 40th long-duration expedition onboard the International Space Station, ISS, returned to Earth after 167 days in space.

Undocking of the Soyuz TMA-12M spacecraft with NASA astronaut Steve Swanson and Russian cosmonauts Alexander Skvortsov and Oleg Artemyev onboard from the station's Poisk module took place as scheduled on Sept. 11, 2014, at 03:01 Moscow Time (7 p.m. EDT on September 10). The spacecraft then initiated a 4-minute, 40-second engine firing to leave the orbit. In the meantime on the ground, rescue team helicopters headed to primary and backup landing sites to support the arrival of the crew.

The touchdown of the descent module also took place as scheduled three and half hours later at 06:25 Moscow Time on Sept. 11, 2014, (10:23 p.m. EDT on September 10) 148 kilometers southeast of Zhezkazgan in Kazakhstan. The spacecraft landed in vertical position and its crew was safely extracted by search and rescue personnel.