After more than six months in orbit, the Soyuz MS-17 mission has drawn to a close. The craft departed the International Space Station with undocking right on time at 21:34 EDT on Friday, 16 April (01:34 UTC on Saturday, 17 April).
Sergey Ryzhikov, Sergey Kud-Sverchkov, and Kate Rubins then conducted final landing preparations before the deorbit burn commenced at 00:01 EDT / 04:01 UTC on Saturday, 17 April followed by a landing near Dzhezkazgan, Kazakhstan at 00:55 EDT / 01:55 UTC.
Undocking to deorbit timeline
Once physical separation was achieved from the Poisk module, springs imparted a 0.12 m/s separation velocity between the Station and Soyuz while both craft were in free-drift. Ten seconds after separation, Soyuz began active attitude control.
Separation burn #1 occurred 3 minutes after undocking, at which point Soyuz burned its thrusters for 8 seconds to impart a 0.53 m/s velocity change to the craft. Separation burn #2 followed and involved a 15 second burn to give Soyuz an additional 1.53 m/s push.
This second burn sent Soyuz out of the Station’s Keep Out Sphere and placed it on its initial free-flight trajectory to begin preparations for deorbit.
After closing the hatches between the Orbital and Descent Modules, the crew oriented Soyuz retrograde. The 4 minute 38 second deorbit burn from the main engine mounted on the back of the Service and Propulsion Module began at 00:01:30 EDT / 04:01:30 UTC and imparted a 128 m/s deceleration to Soyuz, lowering its perigee into Earth’s atmosphere at a precise point to allow the module to land where intended.
Separation of the Soyuz into its three constituent components occurred 140 km over Egypt at 00:29:55 EDT / 04:29:55 UTC followed by Entry Interface — the point where it reaches the discernable atmosphere — at 121 km.
The plasma regime of reentry began at 80.6 kilometers altitude, at which point communications ceased with the craft as the intensity of the plasma blocked all communication frequencies.
Reestablishment of contact with Soyuz usually occurs first with acquisition of signal and transmission of tones to recovery forces who need to track the craft’s exact location.
Communications were reestablished once Soyuz exited the plasma environment at 37 km, which occurred at 00:39 EDT / 04:39 UTC.
Parachute deployment was commanded at 10.7 km above the local terrain, followed 13 minutes later at 00:55 EDT / 04:55 UTC by a retro-rocket-assisted landing.
This timeline was based on a nominal reentry trajectory. Soyuz had a backup trajectory available — known as a Ballistic Reentry — in the event an emergency is detected after the deorbit burn occurs.
This type of emergency reentry profile last occurred on back-to-back Soyuz TMA landings on the TMA-10 and -11 missions when the Service Module failed to fully separate from the Descent Module.
When this occurred, the Descent Module’s computers triggered a ballistic reentry on both flights – a trajectory designed to get the crew through reentry as quickly as possible to maintain their safety.
Ballistic reentries are much steeper than standard entries, exert higher G-force loads on the crew, and result in a landing hundreds of kilometers from the intended recovery zone.
In both the Soyuz TMA-10 and -11 cases, the ballistic reentry worked as intended with a safe recovery of the crew.
Sergey Nikolayvich Ryzhikov:
Soyuz MS-17 was commanded by Sergey Ryzhikov, a veteran Roscosmos cosmonaut who has racked up 358 days in space over the course of two long-duration flights to the ISS.
Ryzhikov was born on 19 August 1974, in Bugulma, a town now known as the Republic of Tatarstan — a federal subject of the Russian Federation. He comes from a military background, having been a fighter pilot in the Russian Air Force, where he spent over 700 hours flying in high performance fighter jets.
Selected by the Cosmonaut Corps in October 2006, he completed training in 2009, following which he earned the title of “Test Cosmonaut”.
In December 2014, he was assigned as a backup Flight Engineer for ISS Expedition 47/48, which successfully launched in March 2016. Following, he was assigned as Flight Engineer for ISS Expedition 49/50.
He made his first flight into space on 19 October 2016 aboard Soyuz MS-02. Ryzhikov served as the Commander of the Soyuz spacecraft and was joined by Russian cosmonaut Andrei Borisenko and NASA astronaut Shane Kimbrough. He spent 173 days in space as a Flight Engineer on Expeditions 49 and 50 before returning to Earth in April 2017.
Ryzhikov was then assigned as backup Commander for Soyuz MS-17 in November 2019, although crew changes in February 2020 resulted in him being bumped to the prime crew.
Successfully launching on 14 October from the Baikonur Cosmodrome, Ryzhikov arrived at the Station just 3 hours later, docking to the Rassvet module. He served as Flight Engineer on ISS Expedition 63 and took command of the Station for Expedition 64 following the departure of Soyuz MS-16.
Ryzhikov handed over command of the ISS to NASA astronaut Shannon Walker on Thursday 15 April.
Sergey Vladimirvich Kud-Sverchkov:
Sergey Kud-Sverchkov was the only first-time space flyer to launch on Soyuz MS-17 and served as Flight Engineer 1 aboard the spacecraft.
Born on 23 August 1983 in Baikonur, Kazakh Soviet Socialist Republic (now The Republic of Kazakhstan), Kud-Sverchkov is unique among the many space travelers who have left Earth from the vast Kazakh steppe as he was born in the same city from which he then launched into space.
After graduating from Moscow State Technical University with a degree specializing in rocket engines in 2006, he went on to work at RSC Energia, the Russian corporation that builds the Soyuz spacecraft and rockets. He worked at Energia until April 2010, when he was selected to train as a cosmonaut.
His training was completed in July 2012, and he qualified as a “test cosmonaut” the following month. He was part of the Roscosmos specialization and improvement group for the ISS program until November 2019 when he was assigned as part of the backup crew for Soyuz MS-17 alongside Ryzhikov.
Like Ryzhikov, crew changes earlier in 2020 resulted in Kud-Sverchkov being bumped up to the prime crew in February.
After launch on 14 October 2020 and arrival at the Station, he served as a Flight Engineer for both Expeditions 63 and 64.
Dr. Kathleen Hallisey Rubins:
Dr. Kathleen “Kate” Rubins of NASA, who has spent 300 days in space over the course of two long-duration flights to the ISS, was Flight Engineer 2 for the Soyuz MS-17 mission.
Born in Farmington, Connecticut on 14 October 1978, Dr. Rubins launched into space for this mission on her 42nd birthday.
Rubins received a Bachelor of Science in Molecular Biology from the University of California in 1999 and went on to earn a doctorate in Cancer Biology from Stanford University in 2005.
She worked at the Salk Institute for Biological Studies in San Diego, where she conducted research into HIV-1. Alongside the US Army Medical Research Institute of Infections Diseases and the Centers for Diseases Control and Prevention, she was part of a team that developed the first model of the smallpox infection. She then led a team of scientists studying viral diseases at the Whitehead Institute for Biomedical Research in Massachusetts.
Dr. Rubins was selected as an astronaut candidate by NASA in 2009, becoming part of the agency’s 20th Astronaut Group, also known as “The Chumps”. She completed her training in November 2011, officially becoming available for future flight assignments.
Her first flight was as a Flight Engineer aboard ISS Expeditions 48/49. She launched aboard Soyuz MS-01, the first flight of the newly upgraded Soyuz MS spacecraft, on 7 July 2016 alongside Russian cosmonaut Anatoli Ivanishin and Japanese astronaut Takuya Onishi. Upon launch, she became the 60th woman to fly in space.
Over the course of Expeditions 48/49, she became the first person to sequence DNA in space and performed two spacewalks alongside fellow NASA astronaut Jeffrey Williams.
She returned to Earth alongside Ivanishin and Onishi on 30 October 2016. With Soyuz MS-17, Dr. Rubins became the first member of her astronaut group to fly in space twice.
She is a member of NASA’s Artemis lunar astronaut corps and will begin training for lunar missions upon completion of Soyuz MS-17.
(Lead image: A Soyuz spacecraft descending under parachute toward the steppes of Kazakhstan. Credit: NASA/Roscosmos)