The Russian Soyuz MS-05 spacecraft undocked from the International Space Station (ISS) and completed its journey back to Earth with its three crewmembers on Thursday. The vehicle undocked at 05:14 UTC ahead of landing on the steppes of Kazakhstan around 08:38 UTC. The Soyuz returned ESA’s Paolo Nespoli, Randy Bresnik of NASA and Sergei Ryazansky of Roscosmos.
Soyuz MS-05’s homecoming – also noted as the End Of Mission (EOM) events – represented the conclusion of the 134th flight of a crewed Soyuz vehicle, which was conducted by the 60th launch of the Soyuz-FG rocket since it entered service in 2001.
That launch took place in late July, using the fast rendezvous technique that resulted in a successful docking at the MRM-1 module of the Station.
It delivered a valuable payload of three humans set for a six month expedition on the orbital outpost.
Sergei Ryazansky – who commanded the Soyuz – carried out his role as Flight Engineer for Expeditions 52 and 53.
NASA’s Bresnik marked his second trip to space and his first long-duration mission, serving as Flight Engineer for the remainder of Expedition 52 before serving as Commander of the ISS for Expedition 53.
Meanwhile, veteran space traveler Nespoli completed his third tour of duty on the Station – and completed more than 60 experiments during his Vita mission, which stands for Vitality, Innovation, Technology and Ability.
Once final farewells were complete, the hatches between the ISS and the Soyuz were closed, prior to the crew completing the translation from the Orbital Module (BO) and Descent Module (SA) to strap themselves into their Kazbek couches inside the SA.
As per the timeline, Soyuz MS-05 undocked from the ISS at 05:14 UTC.
At the time of undocking, Expedition 54 began aboard the station under the command of Misurkin. Along with his crewmates Mark Vende Hei and Joe Acaba of NASA, the three-person crew will operate the station until the arrival of three new crew members five days later.
Following undocking, Soyuz enjoyed a few hours of free flight as it departed from the Station’s neighborhood via two separation burns while the onboard crew prepared for the final aspect of their mission.
The deorbit burn occurred at 07:44 UTC, reducing the Soyuz’s velocity just enough for it to begin the plunge back to Earth via a 4 min, 40 second retrograde firing.
The Soyuz then entered the critical part of its mission as the spacecraft had no other option but to re-enter.
The first milestone was module separation as the three major elements of the Soyuz spacecraft – the OM, DM and Instrumentation/Propulsion Module (IPM) – were pushed apart via the use of pyrotechnics.
All three modules nominally separate simultaneously – shortly after the deorbit burn was completed – at around 140 km altitude.
Two “off nominal” re-entries occurred in 2007 and 2008 and were the cause of separation failures on the modules, thus initiating a very stressful return for their three-person crews. Known as “ballistic entry” – the crew have to endure much higher G-forces and land at an alternative site.
An investigation (L2 Russian Section) noted issues with the long-term exposure to electromagnetic emissions on-orbit, and the potential to cause issues with the pyro bolts, came after an extensive investigation that included the removal and return of one pyro bolt from Soyuz TMA-12.
Mitigation against this issue has resulted in no further issues with the module separation milestone in any of the following missions.
Once through the plasma of entry interface, the capsule prepared for the deployment of its drogue chute. This prepared the spacecraft for the deployment of its main parachute. This is one of the hardest parts of the return for the crew, which has been described as being inside a washing machine by some returning astronauts.
The Soyuz craft then completed the return to terra firma, landing on the steppes of Kazakhstan at around 08:38 UTC.
The exact timing of touchdown, under a “soft” thruster engine firing, is always dependent on a number of factors – such as the impact of winds on the Soyuz chutes – and can vary by several minutes.
With the Soyuz safely back on Earth, ground and air crews converged on the Soyuz and extracted the crew from the SA.
The crew underwent immediate and preliminary health checks once outside their Soyuz spacecraft. All three are then transferred to a medical tent and then prepared for transit away from the landing site.
Eventually, they will part ways to their respective countries and space agencies.
(Images: NASA, Roscosmos, ESA and L2. To join L2, click here: https://www.nasaspaceflight.com/l2/)