Oleg Kotov (Russia), Timothy Creamer (NASA) and Soichi Noguchi (Japan) have launched on board the Russian Soyuz TMA-17 on Sunday, taking aim on the International Space Station (ISS) where they will join NASA’s Jeff Williams, commander of the Expedition 22 crew. The crew launched at 4:51pm Eastern from the Baikonur Cosmodrome in Kazakhstan.
The launch vehicle lofting the Soyuz TMA-17 into orbit is the Soyuz-FG. The vehicle was introduced in 1966, deriving from the Vostok launcher, which in turn was based on the 8K74 or R-7a intercontinental ballistic missile. It has become the world’s most used space launcher, flying over 850 times.
The four boosters on the first stage are arranged around the central core and are tapered cylinders with the oxidizer tank in the tapered portion and the kerosene tank in the cylindrical portion. As in the entire Soyuz lower composite, the RD-107A engines of the boosters are powered by nontoxic liquid oxygen – kerosene propellants.
These spark ignition engines are fed by a turbopump running off gases generated by the catalytic decomposition of H2O2 in a gas generator. Each RD-107A has four combustion chambers and nozzles. Liquid nitrogen is used for pressurization of the propellant tanks.
Attitude control is carried out through two movable vernier thrusters and one aerofin. Three-axis flight control is made possible through these eight engines (two per booster) and four aerofins (one per booster). The boosters burn for 118 seconds and are then discarded.
Thrust is transferred through a ball joint located at the top of the cone-shaped structure of the booster, which is attached to the central core by two rear struts.
The second stage – or Core Stage – is similar in construction to the booster stages, using the RD-108A engine and four vernier thrusters for three-axis flight control. The core stage nominally burns for 290 seconds. The stage is shaped to accommodate the boosters, and a stiffening ring is located at the upper interface between the boosters and central core.
The boosters and the central core are ignited on the ground. They burn at intermediate thrust levels for approximately 20 seconds before actual liftoff in order to verify their health and nominal level of operation. The core stage continues to function after booster shutdown and separation.
Ignition of the third stage’s single main engine occurs approximately two seconds before shutdown of the central core. The separation of the stages takes place at a predetermined velocity. After separation, the lower skirt of the third stage is jettisoned in three sections. The third stage of the Soyuz is powered by the RD-0110 engine.
The third-stage engine is powered by a single turbopump spun by gas from combustion of the main propellants in a gas generator. These combustion gases are recovered to feed four vernier thrusters that handle attitude control of the vehicle. For deorbitation and collision avoidance, a reaction nozzle is positioned on the side of the stage and vents the oxygen tank.
The LOX tank is pressurized by the heating and evaporation of the oxygen, while the kerosene tank is pressurized by combustion products from the gas generator. An interstage truss structure connects the core stage with the third stage, thereby allowing for the ignition of the third stage before separation of the second. In fact, this ignition assists the separation of the second stage.
The Soyuz Vehicle the crew are riding on consists of three modules: the Orbital Module, the Descent Module (DM), and the Instrumentation/Propulsion Module (IPM). The DM is the only module that returns to Earth, after all three modules nominally separate simultaneously, shortly after the deorbit burn is completed.
After a two-day trip, the Soyuz will dock to the space station at 4:58 p.m. on Tuesday, Dec. 22, beginning the crew members’ six-month stay. Kotov, Creamer and Noguchi will join Williams and Russian Flight Engineer Maxim Suraev, who have been on the complex since October.
This will be the 104th flight of the Soyuz since 1967, and will be the only crewed vehicle for the ISS for several years – if current plans to retire the shuttle over the next 12 months or so remain unchanged.