Safely in Orbit – Soyuz Crew begins Two-Day Commute to Space Station

Originally posted on September 1

Photo: ESA

An international crew of three started a two-day journey to the International Space Station, safely launching into orbit atop a Soyuz FG rocket on Wednesday. Aboard Soyuz TMA-18M, veteran Commander Sergei Volkov and rookie space fliers Andreas Mogensen and Aidyn Aimbetov blasted off at 4:37 UTC from Site 1/5 at the Baikonur Cosmodrome.

Performing a nine-minute climb into orbit, the Soyuz FG rocket successfully sent the Soyuz spacecraft on its way, set to stick to the scenic route with docking to the Poisk Module of ISS planned on Friday.

Climbing into the spacecraft sitting atop 274 metric tons of explosive propellants, Sergei Volkov was looking forward to his third trip into space as a Soyuz commander. Andreas Mogensen, the first Dane to travel to space, and Aidyn Aimbetov, launching after waiting for his chance to fly to space for a decade, are set for a short-duration visit to ISS packed with scientific experiments before returning to Earth next week aboard the Soyuz TMA-16M spacecraft.

The three crew members are eagerly awaited by the Space Station’s resident crew for a direct handover that facilitates the switch in Soyuz spacecraft for Scott Kelly and Mikhail Kornienko who are hitting the halfway-point in their one-year Expedition soon.

To facilitate a long-duration mission of one year, the two crew members have to launch aboard one Soyuz and land aboard a vehicle launched later, given the 215-day lifetime limit of the craft.

Mogensen and Aimbetov will switch seats with the one-year crew and return to Earth with Gennady Padalka. Sergei Volkov will complete a half-year tenure as ISS Flight Engineer before returning to Earth with Kelly and Kornienko in March of 2016.

Now on their way to their destination in space, the three crew members will live aboard the Soyuz for two days, employing the standard 34-orbit rendezvous scheme because phasing with the Space Station had drifted out of place as the result of Debris Avoidance Maneuvers in July and the setup of phasing for next week’s Soyuz TMA-16M landing. Volkov, Mogensen and Aimbetov will share the confined quarters of the Soyuz until Friday, set for docking at 7:42 UTC to mark a one-week handover with nine people on board the Space Station.

The on-ramp to Space for the crew trio was the Baikonur Cosmodrome, the storied space port that has supported crewed missions for over five decades. Launch Operations picked up in the overnight hours on Tuesday when technicians reported to the launch pad at Site 1/5 to begin preparing the 50-meter tall Soyuz rocket for the initiation of the countdown.

Photo: Roscosmos
Photo: Roscosmos

To support their 10:37 a.m. local time liftoff, the crew members had to shift their sleep cycles, being woken up nine hours prior to their scheduled T-0 time to head into a busy countdown, starting with their final medical preparations consisting of a final pre-flight shower, medical checks and a whole-body disinfection plus microbial sampling to protect the pristine environment of the Space Station as teams go through great lengths to keep germs out.

As part of their departure of the Cosmonaut Hotel, the crew signed their hotel room doors, putting their names next to those who also spent time at the hotel before leaving the planet. Six hours ahead of liftoff, they departed the hotel, receiving the traditional pre-flight blessing by an Orthodox Priest and walking out to the traditional song ‘Trava U Doma’ by Zemlyane playing over the speakers as the crew was seen off by families and friends as well as Cosmodrome personnel wishing them a safe journey. Driving to Site 254 at the Cosmodrome, the three crew members had a little under an hour of quiet time before heading into a busy countdown operation.

Out at Site 1/5, countdown procedures were formally initiated eight hours prior to launch as teams headed into a methodical process to prepare the Soyuz rocket and spacecraft for flight. To start the lengthy countdown, Soyuz FG and TMA-18M were powered up to head into a detailed round of testing – going through electrical checks, propulsion system verifications, Flight Control System checkouts and communication checks, involving both, the launcher and the spacecraft.

Photo: Tsenki
Photo: Tsenki
Photo: Tsenki
Photo: Tsenki

Engineers installed charged batteries on the different stages of the Soyuz rocket at L-6 hours while tanking preparations were also being wrapped up as the tanking cars were rolled up to the launch pad and connected to ground propellant handling systems. The red-tagged ‘Remove before Flight’ covers were removed from the core stage and booster engines, different plugs and sensors and equipment on the third stage.

The Russian State Commission convened at L-5 hours and 30 minutes to review the results of launch vehicle and spacecraft testing performed over the last two days and look at the current status of countdown operations. With no outstanding items, the State Commission cleared the Soyuz for propellant loading.

Subsequently, engineers put in motion the final steps to prepare for tanking. Propellant loading picked up just inside L-5 hours with a brief chilldown of the Liquid Oxygen transfer lines and tanks before the supercold -183°C oxidizer began flowing into the boosters, the core stage and the Block I third stage, fed to the tanks through the different umbilical towers of the rocket. Kerosene loading was initiated a short time later to fill the tanks of the Soyuz rocket with a total of 274,140 Kilograms of rocket propellant.

In addition to propellants to be consumed by the engines, the boosters and core stage received 280kg and 520kg of Liquid Nitrogen, respectively, for use as a tank pressurant – heated up by the engines during flight and fed to the tanks to keep them at the proper pressure. Prior to countdown ops, the boosters and core stage were also loaded with Hydrogen Peroxide, used to drive the turbopumps of the engines.

With over 1,800 flights under its belt, looking back at a 50 year career, Soyuz is a world leader in the launch business in terms of flight heritage, a well established success rate and it remains at the top of the launch list consistently every year, flying more missions than any other launcher.

Building on heritage of the original R7 ICBM developed in the 1950s and 60s, Soyuz FG stands 49.5 meters tall and spans ten meters from booster fin to booster fin. It has a total launch mass of 305,000 Kilograms and can loft the 7,200-Kilogram Soyuz into orbit with ease. The Soyuz FG uses the familiar design consisting of a large core stage with four liquid-fueled boosters clustered around it and a third stage sitting atop and Soyuz stacked on top of that, protected by its launch shroud.

Photo: Tsenki TV
Photo: Tsenki TV

Each of the four liquid-fueled boosters is 19.6 meters long and 2.68 meters in diameter consisting of a tapered portion that facilitates the oxidizer tank that is located above the fuel tank which is housed inside the cylindrical portion. Each booster uses a single four-chamber RD-107A engine that delivers 838.5 Kilonewtons of sea level thrust and consumes 39,600 Kilograms of propellants over the course of its burn.

The Soyuz FG Core Stage is 27.8 meters long and 2.95m in diameter holding 92,950 Kilograms of LOX and Kerosene at launch. It sports a four-chamber RD-108A engine and four verniers for vehicle control. The engine delivers 792 Kilonewtons of launch thrust increasing to 990kN in vacuum.

Soyuz FG uses a 6.74-meter long third stage that is 2.66m in diameter & loaded with 22,890kg of propellants for use by the four-chamber RD-0110. The open-cycle Gas-Generator engine provides 298kN of vacuum thrust and uses four verniers for vehicle control.

Soyuz FG propellant loading was completed without any issues when countdown clocks passed L-3 hours. Kerosene tanks were fully loaded and LOX and Liquid Nitrogen entered replenish, being kept at topping level as the cryogenics naturally boiled off. To make room for crew arrival, the Tanking Cars were disconnected and pulled away from the pad, being parked at a safe distance for launch.

Photo: Tsenki TV
Photo: Tsenki TV
Photo: NASA TV
Photo: NASA TV

Volkov, Mogensen and Aimbetov arrived at Site 254 five hours prior to launch – a former support building for the Soviet Buran shuttle, now in use for processing of Soyuz and Progress spacecraft as well as crew and equipment support. The crew members went through a last medical check before being helped by suit technicians when putting on their Sokol Launch and Entry suits inaugurated in the 1970s to protect crews in the event of a cabin depressurization during launch or re-entry.

One at a time, the crew went through a leak check on their suits. While one crew member was in a Kazbek seat mock-up having his suit tested, the others were able to have a chat with their families through a pane of glass separating the quarantined crew from the press room.

The Soyuz trio departed Site 254 at Launch minus three hours, reporting to officials before boarding the bus for a ride of 20 minutes, taking then to Site 1/5, the prime launch pad used for crewed missions. Nearly 500 launches were supported by the launch facility, including the vast majority of crewed launches using the Soyuz.

The crew’s bus passed through the gates to Site 1/5 and stopped in front of the Soyuz, allowing the crew members to take a close look at their venting launch vehicle. After a short exchange with space agency officials and a moment for a photo opportunity, the crew walked over to the Service Structure stairs from where they waved good bye. Boarding the elevator, the crew was taken up 15 floors to a small room adjacent to the launch shroud where teams had prepared for the ingress of the crew.

Pressing into crew ingress, the two Flight Engineers were up first – climbing through a hatchway in the protective launch shroud, into the Orbital Module through its side hatch and down into the Entry Module via the internal Soyuz hatch. Andreas Mogensen was strapped into the left seat of the Soyuz while Aidyn Aimbetov boarded the right seat before Sergei Volkov entered the commander’s seat in the center.

Photo: Gagarin Cosmonaut Training Center
Photo: Gagarin Cosmonaut Training Center
Photo: Tsenki TV
Photo: Tsenki TV

Sergei Volkov, the first Cosmonaut in second generation, served in the military as a pilot, though his military career was rather short given his early selection as a Cosmonaut. Selected in 1997, Volkov made his first flight aboard Soyuz TMA-12 spending half a year on ISS as part of Expedition 17. He was one of the first Cosmonauts trained on the Digital Soyuz TMA-M craft and flew for a second time as part of Expeditions 28/29. He logged a total of 365 days in space and performed three spacewalks.

Andreas Mogensen comes from an engineering background. Holding a PhD, Mogensen worked on different aspects of space engineering including attitude and orbit control as well as precision landing. Selected by ESA in 2009, Mogensen will become the first Dane to fly to space, set for a busy science mission.

Aidyn Aimbetov can also look back at a military pilot career before being selected as one of two Kazakh Cosmonauts in 2002. Initially expected to fly in 2007, Aimbetov’s hopes of flying into space faded as financial problems within Kazcosmos kept him on the ground. However, Aimbetov remained flight ready and kept up his certifications – a strategy that paid off when Sarah Brightman withdrew from her planned tourist flight, opening a seat that had to be filled on short notice.

Once inside the Soyuz craft, the three crew members went through initial setup tasks, plugging their suits into ventilation and communications systems and heading into the pre-launch checklist that kept them busy for one hour, running communication checks and preparing the Soyuz craft for the terminal countdown operation. With the crew in their seats, teams closed the Entry Module hatch and removed any access platforms and protective covers from the Orbital Module before shutting the side hatch. The next step was a leak check on the Soyuz completed by pressurizing the spacecraft and monitoring pressures to ensure both hatches were holding pressure.

Engineers closed out the launch shroud, removing the access tunnel and closing up the shroud hatch. In the meantime, technicians finished the close outs of the Soyuz rocket and began retracting access platforms. As part of their checklist, the Soyuz crew went through a leak check on their suits to make sure all were ready for launch.

At the completion of the pre-launch checklist, the crew had some quiet time as countdown operations progressed without need for crew action. The crew selected some music tracks that were played in the 45 minutes leading up to launch on the comm loops to make the time of waiting a little shorter for the trio.

Photo: Tsenki TV
Photo: Tsenki TV

Heading into the final hour of the countdown, the Soyuz FG Guidance System was powered up and entered its configuration for liftoff as the flight software calculated for this mission was uploaded to the flight computer. At the same time, teams evacuated the Service Structure and non-essential personnel departed the launch pad. The two halves of the Service Structure began opening at L-39 minutes to reveal the fully-fueled Soyuz on its pad, clearing its path for liftoff. Once the structure was fully lowered, it was secured for launch and had its main power feed cut.

With half an hour on the countdown clock, the SAS launch abort system was activated and placed in a safe mode for checkouts before transitioning to Auto Mode 15 minutes ahead of launch – ready to trigger an abort upon command from controllers and automated systems to carry the crew to safety in the event of a major failure while Soyuz was sitting on the launch pad or at any point in its ascent into orbit.

As clocks ticked down, all personnel reported to launch position – either at a safe distance or inside the nearby bunker from where the countdown was controlled. Soyuz TMA-18M switched to internal power 14 minutes prior to launch under the watchful eyes of the crew that then made the final switchthrows to configure the Soyuz for terminal count.

Starting the Automated Countdown Sequence six minutes before T-0, Soyuz entered a highly choreographed procedure to achieve its autonomous launch configuration. Inside the launch bunker near the pad, the launch key was inserted and turned to the proceed position. Soyuz Telemetry Systems were activated and the crew closed their helmets at T-5 minutes, verifying they had the correct checklists ready and continuing to monitor their displays to track the status of the vehicle.

Photo: ESA TV
Photo: ESA TV

At T-4 minutes, the nitrogen purge of the RD-107A and RD-108A engines of the boosters and core began in order to remove any combustible substances in order to ensure a controlled ignition. Pressurization of the propellant tanks started at T-2 minutes and 35 seconds as propellant fill&drain valves closed and safety valves were commanded to close as well. All tanks on the core and boosters achieved flight pressure a short time later and the ground feed of LOX and LN2 was terminated. Two minutes before launch, the Onboard Measurement System was activated.

At the T-1-minute mark, the Soyuz switched to internal power and the onboard launch sequencer assumed control of the countdown’s final critical events. The third stage umbilical was disconnected 40 seconds before launch and the umbilical tower was moved to its launch position.

20 seconds ahead of liftoff, the ignition sequence was started and the turbopumps of the booster and core stage engines started-up, spinning up to flight speed. The engines were commanded to an intermediate thrust level before soaring up to full thrust five seconds ahead of liftoff – monitored by computers to verify that all reached operational conditions.

Photo: ESA TV
Photo: ESA TV
Photo: ESA TV
Photo: ESA TV
Photo: ESA TV
Photo: ESA TV

The crew’s adventure started at precisely 4:37:43 UTC when the Soyuz rocket started rising from the pad, overcoming counterweights with its launch thrust of 422 metric ton-force. Firing its engines at full throttle, Soyuz used the small gimbaling verniers of the boosters and core stage to balance in a vertical position, going up straight as an arrow for ten seconds before pitching over.

Soyuz used the standard departure path, pitching over to fly north east towards the Kazakh-Russian border, beginning to chase the Space Station that was flying over south-central Kazakhstan when Soyuz lifted off. ISS was in-plane above the launch site 47 seconds ahead of liftoff and Soyuz was targeting an orbit at a 382-degree phase angle to that of ISS to be flown out during the two-day transit to the Station. For a four-orbit rendezvous, the phase angle would have needed to be below 40 degrees which was no longer an option after the recent orbital changes by ISS.

Immediately after leaving the ground, the crew reported that everything was looking good on their end and they were feeling good, starting a nine-minute ride into Low Earth Orbit.

Burning 1,600 Kilograms of propellants per second, Soyuz quickly lost weight and was accelerating swiftly. The rocket headed through the sound barrier 50 seconds into the flight followed a short time later by Maximum Dynamic Pressure encountered when the vehicle had already climbed to an altitude of 11 Kilometers.

Doing most of the work during the initial portion of the flight, the four boosters delivered the thrust needed to send Soyuz off on its way into orbit, helping accelerate the vehicle to a speed of 1.5 Kilometers per second. With the engines running smoothly, the crew found a few moments to wave at the cameras, visibly enjoying their ride.

One minute and 54 seconds into the flight, the Launch Escape Tower was jettisoned and fired its rockets to pull away from the rocket – marking the switch of the Launch Abort System to its mid-altitude mode, using a different set of engines to move Soyuz to safety in the event of a problem.

The RD-107A engines of the boosters were shut down 118 seconds into the flight after each burned 39,600 Kilograms of propellants to deliver 101,400kgf of thrust to the vehicle for the initial flight portion. At an altitude of 49 Kilometers, the four boosters were separated by firing separation pyros and pistons that pushed the four boosters outward and sent them into a wild tumble – forming a phenomenon known as the Korolev Cross visible for a very brief moment as the boosters move outward with the burning Core Stage in the center. The boosters impacted 350 Kilometers downrange from the launch site.

With the boosters gone, the Soyuz relied on the power of its core stage alone. The RD-108A engine burned 320 Kilograms of LOX and Kerosene per second to generate 94 metric tons of thrust, using four gimbaling verniers to stabilize the vehicle on its course towards orbit.

Passing 85 Kilometers in altitude two minutes and 40 seconds into the flight, it was safe for Soyuz to get rid of some no-longer necessary weight by separating the launch shroud. The shroud made a clean departure, exposing the Soyuz spacecraft for the rest of the way into orbit and giving the two space rookies, Andreas Mogensen and Aidyn Aimbetov, their first look at Earth with its thin atmosphere and cloudy skies. Though their focus were the instrument panels of the Soyuz, the two crew members likely took a short moment to have a glance out the small Entry Module windows – getting a taste of what they will see from the Station’s Cupola.

Photo: ESA TV
Photo: ESA TV
Photo: ESA TV
Photo: ESA TV
Photo: ESA TV
Photo: ESA TV

Approaching the end of the core stage burn, the crew came up on one of the most dynamic flight events starting with a gradual build-up of thrust as the vehicle got lighter and lighter towards the end the RD-108A burn. The engine was shut down at T+4 minutes and 45 seconds followed two seconds later by the command to ignite the RD-0110 engine of the third stage. Built for hot-staging, the interface between the core and 3rd stage consists of a truss segment to allow engine exhaust to escape during start-up because separation pyros are fired after a short delay so that the engine can push the spent core stage away and send it on its way to an impact 1,570 Kilometers from the launch site.

As the RD-0110 engine of the third stage soared to its full thrust of 30,400 Kilogram-force, calls made from the Launch Bunker remained positive, reporting good structural parameters, nominal stabilization and engine pressures as well as a nominal trajectory. The Block I third stage was tasked with finishing the job of boosting the Soyuz into orbit by burning its engine for three minutes and 58 seconds.

Ten seconds into the operation of the third stage, the aft section covers were jettisoned to fully expose the engine compartment and allow the four gimbaling verniers to stabilize the launch vehicle. The five-second sequence from Core Stage shutdown to third stage thrust build-up is the most turbulent event of the ascent for the three crew members, going from 3Gs to almost zero when the core stage shuts down which catapults the crew forward, held in place by their shoulder straps. Moments later, the crew is pushed back into their seats as the third stage engine fires up and the stages are separated.

Consuming 96 Kilograms of propellants each second of flight, the third stage delivered a flawless performance, keeping the ship on course as it sailed into orbit. The crew again experienced an increase in G forces as the end of propulsive flight approached leading up to engine shutdown at T+8 minutes and 45 seconds and the onset of weightlessness. All sense of acceleration stopped and the crew as well as their Zero-G indicator began floating.

Soyuz TMA-18M was aiming for the standard insertion orbit of 200 by 242 Kilometers with the typical tolerances of +7/-22 Kilometers on perigee and +/-42 Kilometers on apogee. The targeted inclination was 51.66 degrees, matching the orbital inclination of the Space Station.

Three seconds after the shutdown of the engine, the Soyuz spacecraft was separated from the Block I rocket stage, being sent on its way into orbit. Now reporting back to Mission Control Moscow, the Soyuz crew confirmed the separation, triggering a fast-paced set of operations conducted based on time-tagged commands stored in the computers of the Soyuz.

Photo: Roscosmos/NASA
Photo: Roscosmos/NASA

Soyuz TMA-18M immediately completed the deployment of its two power-generating solar arrays. The advantage of launching in daylight was that solar array deployment could be immediately confirmed by looking at the current delivered by both of the arrays. After two recent Soyuz missions – TMA-14M and TMA-17M that encountered trouble with one of the solar arrays, teams were relieved to see a clean deployment of both solar arrays. Mission Controllers also watched over the deployment of communications and KURS navigation antennas completed eight seconds after separation from the rocket. All appendages were confirmed in their extended position, marking the completion of a smooth launch sequence.

Soyuz TMA-18M successfully pressurized its Unified Propulsion System to soon begin using its DPO thrusters to null-out any residual body rates and enter a favorable attitude for power generation. Checkouts of the SKD main propulsion system and the flight controls of the Soyuz are to be done in the first orbits of the flight.

Next for the crew was a short check of all onboard systems including cabin pressures. With no indication of any leaks, Mission Control allowed the crew to open their helmets, get out of their seats and ingress the Orbital Module. Without the time pressure of the six-hour rendezvous, the crew had plenty of time to go through their initial steps after being cleared for their orbit #1 operations. While Soyuz was still flying over Russian ground stations, it was tracked using radio and radar equipment to obtain a precise fix on its orbital parameters. These parameters are going to be used by ballistics officers to recalculate the Orbit #3 engine burns to properly position the Soyuz for its approach to ISS.

Now en-route to the International Space Station, their destination in space, the three crew members will make use of the 34-orbit rendezvous profile used by the Soyuz for decades before the new express mission profile was inaugurated in 2012 – allowing the Soyuz craft to deliver its crew to the comforts of ISS in just six hours. However, to be able to rendezvous with ISS in four orbits, Soyuz has to be launched into a precise orbital setup, carefully planned with small ISS orbit adjustments beginning around six weeks prior to a targeted launch to set up orbital phasing. Because ISS had to perform two Debris Avoidance Maneuvers in July and the phasing requirements for the Soyuz TMA-16M landing took priority, Soyuz TMA-18M reverted from a planned six-hour flight to ISS to the longer two-day mission.

Photo: NASA
Photo: NASA

After a series of initial reconfigurations to transition the Flight Control System from launch mode to its free flight configuration, the crew members will get out of their Sokol launch and Entry Suits and set up the orbital module for their two-day commute to the Space Station.

Soyuz TMA-18M will receive an update on its orbital parameters during the mission’s first ground station pass following the completion of the first orbit. During the third orbit of the mission, Soyuz TMA-18M will conduct a pair of engine burns, separated by about half an orbit. The orbital maneuvers are targeting an orbit of 236 by 295 Kilometers to place the Soyuz in the proper orbit to catch up with the Space Station. Another engine burn will take place during the 17th orbit of the mission to put the Soyuz in the appropriate orbit taking it to a position from where it can enter its Automated Rendezvous Sequence.

The Automated Rendezvous Sequence will be initialized at 5:15 UTC on Friday. During the Rendezvous Sequence, the Soyuz will complete more engine burns to link up with the Space Station. A two-way voice link between ISS and Soyuz TMA-18M will be established to provide comm relay to Mission Control. The Space Station will hand to Russian Attitude Control and the KURS Systems of ISS and the Soyuz will be activated.

KURS performance will be verified as part of the standard short test to make sure the system is providing good navigation data to the Soyuz. Once entering the vicinity of ISS, the Soyuz activates its TV system and performs a number of rendezvous impulses with its small DPO thrusters to get ready for the Flyaround Sequence starting at a range of 400 meters at 7:13 UTC.

Making a slow lap around ISS, Soyuz TMA-18M will line up with the Poisk Module. At a distance of 180 meters, the approach will be stopped for a short period of Stationkeeping to give mission controllers a chance to verify good alignment and perform a short systems check.

Once the command for final approach is sent, the Soyuz fires its DPO thrusters to initiate a gentle closing rate. During final approach, Soyuz retracts one of its KURS antennas and keeps itself aligned with the docking port. Contact & Capture is expected at 7:42 UTC (+/-3 minutes) to mark the arrival of Sergei Volkov and two Taxi crew members aboard ISS.

Following docking, the docking probe of the vehicle will retract and hooks & latches will be closed to form a hard mate between Soyuz and ISS. The standard leak check operation will follow to ensure the seal between the Soyuz and ISS is tight. Hatch opening is planned around 10:15 UTC on Friday.