Soyuz modules

• Overview
• Instrumentation/Propulsion Module
• Descent Module
• Orbital Module
• Diagrams
• Links
• Photo gallery

On this page, more detailed descriptions of the Soyuz’s three modules.

Overview

The Soyuz TMA, like the Progress cargo ship, is comprised of three compartments: a propulsion module, landing module and a utility module. Up to three cosmonauts can be carried into orbit (somewhat cramped accommodations for three full-grown men!) for 3 days or 34 orbits until docking with the ISS. The Soyuz remains docked as an emergency lifeboat for up to 200 days or 6 months until being replaced by a new ship. Up to 100 kg of cargo can be carried as well, and 50 kg returned to Earth (150 kg if only 2 crew members).

Characteristics

Soyuz TMA: basic data

Article number	11F732
Manufacturer’s designation	7K-STMA
Manufacturer	Korolev
Crew size	2-3
Design life	14 days
Orbital storage	200.00 days
Typical orbit	407 km circular orbit, 51.6° inclination
Length	6.98 m
Basic diameter	2.20 m
Maximum diameter	2.72 m
Span	10.70 m
Habitable volume	9.00 m³
Mass	7220 kg
Main engine	KTDU-80
Main engine thrust	400 kgf
Main engine propellants	N2O4/UDMH
Main engine propellants	900 kg
Main engine isp	305 sec
Spacecraft delta v	390 m/s
Electrical system	Solar panels, span 10.60 m, area 10.00 sq. m
Electric system	0.60 average kW
Associated launch vehicle	Soyuz FG

Instrumentation/Propulsion Module
Приборно-Агрегатный Отсек

Soyuz TMA: Instrumentation/Propulsion Module data

Length	2.26 meters
Basic diameter	2.15 m
Mass	2900 kg
RCS coarse № × thrust	16 × 10 kgf
RCS fine № × thrust	8 × 10 kgf
RCS coarse backup № × thrust	No separate backup translation engines
RCS propellants	N2O4/UDMH
Main engine	KTDU-80
Main engine propellants weight	310 kg
Main engine thrust	632 kgf
Main engine propellants	N2O4/UDMH
Main engine propellants weight	880 kg
Main engine isp	302 sec
Electrical system	Solar panels, span 10.60 m, area 10.00 m.²
Electric system	0.60 average kW

The rear module of the Instrumentation/Propulsion Module (PAO) is itself divided into three components:

• The Intermediate Compartment provides the structural attachment to the Descent Module and contains oxygen storage tanks and attitude control thrusters. The compartment is a cylindrical pressure vessel containing avionics, communications and control equipment. The service section is the structural interface with the launch vehicle and includes the propulsion system, batteries, solar arrays and radiators.
• Inside the Instrumentation Compartment are avionics equipment containing the primary guidance, navigation, control and computer systems for the entire Soyuz spacecraft. The compartment is a sealed pressure vessel containing nitrogen, and the equipment within it is cooled by circulation of the gas. It also contains the primary thermal control system, including the body-mounted radiator with an area of 8 m² (86.1 ft²).
• The propulsion system inside the Propulsion Compartment performs all orbital maneuvers, including those needed for rendezvous with the ISS and the deorbit maneuver required at the end of the mission. The propellants are nitrogen tetroxide (oxidizer) and unsymmetric-dimethylhydrazine (fuel). The propulsion system shares its propellant tanks with the reaction control system that provides attitude control throughout the orbital phase of flight.

The PAO is separate from the other two compartments, and can’t be accessed by the cosmonauts. Its functions are controlled remotely by TsUP, Moscow Mission Control.

Soyuz propellants

The propellants (fuel and oxidizer) in the Soyuz are:

• Unsymmetric Dimethyl Hydrazine (UDMH). The propellant fuel.
• Nitrogen Tetroxide (N₂O₄). An oxidizer (provides a source of oxygen so the fuel can ignite and burn, as there is no oxygen in orbit).
• Hydrogen Peroxide (H₂O₂). Another oxidizer, used in the Descent Module’s Reaction Control System. Used in the main engine of the Propulsion Module and also its RCS.

The Soyuz’s stay in orbit is limited as the H₂O₂deteriorates over time, as this ISS On-Orbit Status Report from 2 September 2004 notes:

Update on Soyuz 9S: Launch of CDR Leroy Chiao and FE Salizhan Sharipov continues to be set for 10/9. Their Soyuz TMA-5 spacecraft is the first with two new features that are welcome improvements of the reliable old crew transport: two additional forward-pointing braking thrusters (#27, #28) besides the two engines (#17, #18) already near the Orbital Module’s docking ring; and a thermo-electric cooler for the Descent Module’s Hydrogen Peroxide tankage, to extend the life of the H₂O₂ which tends to deteriorate in time to H₂O and O. (H₂O₂ is one of the most powerful oxidizers known – stronger than chlorine, chlorine dioxide, and potassium permanganate, but it has been [and still is, until certification] limiting Soyuz’ orbital stay time).

As noted in that extract, the addition of the cooling system for the H₂O₂ only extends the stay-in-space to 180-210 days (6-7 months) rather than a year as intended in the original more extensive Soyuz upgrade (called Soyuz TMM). This would have also included the installation of improved storage batteries and the oxidizer tanks to be made from steel rather than the current aluminum alloy.

Descent Module
Спускаемый Аппарат

Soyuz TMA: Descent Module data

Length	2.24 m
Basic diameter	2.17 m
Maximum diameter	2.17 m
Habitable volume	3.50 m³
Mass	2950 kg
Crew mass	255 kg
Payload	1355 kg
Return payload	50 kg (crew of 3), 150 kg (crew of 2)
RCS coarse № × thrust	6 × 10 kgf
RCS propellants	H2O2
RCS propellants	40 kg
Main engine propellants	45 kg

The Descent Module (SA) is the command center of the Soyuz craft; this middle section contains all the mission-critical controls and displays. The spacecraft is operated by a digital computer, and displays are presented on two amber digital screens in the TMA version.

During ascent and descent, the two or three crew recline in Kazbek-U, «Казбек-У» seats; each crew member has a special seat liner moulded to his or her physical dimensions when seated on their back with knees up. The module is stuffed with life support equipment for every conceivable environment and situation that might be encountered upon landing.

The environmental system keeps the temperature around 18-20°C, and humidity at 40%. The atmosphere is a nitrogen/oxygen mix, like that of Earth’s.

Two small windows are set to port and starboard, at the elbows of the crew in the left and right-hand seats. (These windows have outside covers which are deployed during the hot plasma phase of reentry, then are jettisoned.) The commander sits in the middle, the first flight engineer to his left, and the second FE or space tourist to his right.

The commander (Командир Экипажа, КЭ, KE) is responsible for overall operations and decisions. He controls and flies the Soyuz during all flight maneuvers, and communicates with the ground. Docking is usually automated, but the commander can take over manual control if the system malfunctions for some reason.

The Soyuz is controlled by two joysticks on either side of the commander:

• The attitude control on the right enables the pilot to roll, pitch (up-and-down) or yaw (side-to-side) the Soyuz around its axis.
• The translation controller allows the pilot to move the Soyuz up, down, forward, back, left and right.

The first flight engineer (Бортинженер, БИ, BI) on the commander’s left and is responsible for thrusters, attitude control, navigation, life-support systems and general vehicle functions.

The third seat on the right is occupied by the second FE, or a guest cosmonaut-researcher (участник космического полета) or “space flight participant” (участник экспедиции посещения) (paying private visitor). In the Soyuz TM they were responsible for monitoring communications, navigation and life support systems, but in the TMA these have been shifted to the first Flight Engineer.

There is no forward-facing window for the commander to look out of, so between his knees is a periscope, through which he can observe the docking mechanism at the forward end, and also look downwards to see the Earth’s surface. To reach the controls he must use a stick to poke at the buttons! (I do not know the name of the stick.)

Like the PAO, the SA has a guidance, navigation and control system; the SA one is independent and less complex. Eight hydrogen peroxide thrusters are used to control the ship’s attitude; these are only employed in the descent phase (as are power batteries for the SA equipment). The propellant tanks are in a separate pressurized volume, sealed with an access cover, as are the primary and backup parachute containers.

The huge primary parachute has concentric orange-and-white stripes. One company, Everquest, has created carry bags from the flown parachute material and is selling them on the Internet!

After the modules separate, only the SA returns to Earth (hopefully!) intact. Landings can be rather rough, especially if there is a wind to catch the parachute and pull the capsule over and along after touchdown! The crew is then hauled out through the single top hatch (or, if the module has ended up on its side, they can crawl out).

The Soyuz improvements were based on NASA requests to accommodate its taller astronauts (perhaps they should eat less American junk food!!). These included:

• Three longer Kazbek-UM impact-absorbing crew seats were installed with new four-mode dampers that adjust the seat adjustment depending on the astronaut mass.
• Re-arrangement of equipment in the capsule above and below the seats to accommodate the longer seats and enlarge the passage area through the forward access hatch. The items modified to accomplish this included a new decreased-height control panel, a new cooling-drying ECS subassembly, and a revised data storage system. The SA primary structure right and left of the seat footrests had to be stamped out 30 mm deep to allow for the longer seats. The primary structure and the routing of pipes and cables had to be changed to accommodate this. The crew cabin was cleared of projecting items.
• Two (of six single-mode) soft landing engines (SLE) were replaced with two new three-mode engines (SLE-M) to improve soft landing performance. The touchdown speed was reduced to from 2.6 to 1.4 m/s versus 3.6/2.6 for the Soyuz TM. Landing with only the reserve parachute was reduced to 4.0 to 2.4 m/s versus 6.1 to 4.3 m/s for the Soyuz TM.
• An improved Kaktus-2V gamma-altimeter replaced the Kaktus-4 in the soft-landing system.
• As a result of these changes, astronauts of from 150 to 190 cm height, up to 99 cm sitting height, and from 50 to 95 kg mass could be accommodated in the Soyuz TMA capsule (previous limits were 164 to 184 cm height, 94 cm sitting height, and 56 to 85 kg mass).

Orbital Module
Бытовой Отсек

Soyuz TMA: Orbital Module data

Length	2.98 m
Basic Diameter	2.26 m
Maximum Diameter	2.26 m
Habitable Volume	5.00 m³
Mass	1370 kg
Docking system	Lightweight male/female with flange-type probe, internal transfer tunnel. Kurs automatic rendezvous and docking system with two Kurs antennae, no tower
Docking collar length	0.22 m
Probe length	0.50 m
Base diameter	1.35 m
Ring diameter	1.35 m
Windows	One “blister” window at the front to provide a forward view

The Orbital Module (BO) provides living space during the orbital phase of the Soyuz flight. Systems in the living quarters are analogous to those in the Zvezda Service Module, though in more compact form. The pressurized sphere contains food lockers, remote controls and the all-important space toilet (albeit a very basic one). The crew attach sleeping bags to the curved walls and sleep in these.

At the forward end of the BO is the docking equipment: Kurs apparatus, connecting hatch and rendezvous antennas. A crew member is stationed at the small blister window to aid the commander during docking.

The pressurized, spherical BO is connected at its rear to the SA by a sealable hatch. Like the Instrument Module, the BO separates from the SA after retrofire during the deorbit maneuver, and disintegrates and burns up upon entering the atmosphere.

Diagrams

• Energiya: cut-away side view (41.7 KB)
• ESA: landing module (66 KB)
• MARS Center site – Inside Soyuz TMA: Re-entry Module:
  • Front view, looking to Service Module. (External link, 79 KB)
  • Side view (external link, 75 KB)
  • Upper view (external link, 65 KB)
• SoyCOM Manual diagrams (external links):
  • Fig.2. БО exterior layout (64 KB)
  • Fig. 3. БО main structural elements (37 KB)
  • Fig. 4. View on the «Диван» (“Sofa”) (panels mounted) (61 KB)
  • Fig. 5. View on the «Диван» (“Sofa”) (panels dismounted) (71 KB)
  • Fig. 6. View on the «Сервант» (“Cupboard”) (panels mounted) (80 KB)
  • Fig. 7. View on the «Сервант» (“Cupboard”) (panels dismounted) (81 KB)
  • Fig. 8. СА interior layout (122 KB)
  • Fig. 8. СА interior layout (continuation) (135 KB)
  • Fig. 9. ПхО layout (72 KB)
  • Fig. 10. ПО body structure (45 KB)
  • Fig. 11. АО configuration (73 KB)
  • Fig. 12. Soyuz antennae layout (86 KB)

Links

• Canadian Space Agency: Crew Location and Responsibilities.
• Encyclopedia Astronautica: Soyuz TMA
• MARS Center: Inside the capsule
• MIT: “IDS for Soyuz TMA and the ISS”: essay by Yurii Tiapchenko featuring lots of details about the information display systems of the Soyuz and Zvezda Service Module (also at Space Encyclopedia ASTROnote)
• NASA: Interactive Soyuz Flash animation
• Russian Space Web: General design and major onboard systems; Habitation section (BO); Reentry capsule (SA); Service module (PAO)

~ Page last updated: 28 April 2008

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