The Soyuz MS (Russian: Союз МС; GRAU: 11F732A48) is the latest version of the Russian Soyuz spacecraft series, first launched in 2016. The "MS" stands for "modernized systems," referring to improvements in navigation, communications, and onboard systems over the Soyuz TMA-M series. Developed and manufactured by Energia, it is operated by Roscosmos for human spaceflight missions to the International Space Station (ISS). Soyuz MS-01, the first flight of the series, launched on 7 July 2016 and docked with the ISS two days later following a checkout phase to validate the new systems. The mission lasted 113 days, concluding with a landing on the Kazakh Steppe on 30 October 2016. The Soyuz MS spacecraft has been involved in one in-flight abort. During the launch of Soyuz MS-10 in October 2018, a booster separation failure on the Soyuz-FG launch vehicle triggered the automated launch escape system. The spacecraft separated from the rocket and returned the crew safely to Earth under parachutes. The crew landed unharmed. Since April 2020, the spacecraft has been launched using the modernized Soyuz 2.1a rocket.
Design
Like earlier versions of the Soyuz, the MS spacecraft variant consists of three sections (from forward to aft in orbit, or top to bottom when mounted on a rocket):
A spheroid orbital module A small aerodynamic descent module A cylindrical instrumentation and propulsion module
The orbital and descent modules are pressurized and habitable. By relocating much of the equipment and usable volume to the orbital module—which does not require heat shielding for atmospheric re-entry—the three-part Soyuz design is both larger and lighter than comparable two-part spacecraft. For comparison, the Apollo spacecraft's pressurized command module provided a crew of three with six cubic metres (210 cu ft) of living space and had a re-entry mass of approximately 5,000 kilograms (11,000 lb), while the Soyuz MS offers the same crew ten cubic metres (350 cu ft) of living space with a re-entry module mass of about 2,950 kilograms (6,500 lb). The Soyuz MS can carry up to three crew members and supports free-flight missions lasting approximately 30 person-days. Its life support system provides a nitrogen–oxygen atmosphere similar to that of Earth, with air pressure equivalent to sea level. Oxygen is regenerated using potassium superoxide (KO2) canisters, which absorb most of the carbon dioxide (CO2) and water exhaled by the crew and release oxygen. Lithium hydroxide (LiOH) canisters are also used to absorb residual CO2. In addition to the crew, Soyuz MS can carry up to 200 kilograms (440 lb) of payload to orbit and return up to 65 kilograms (143 lb) to Earth. The spacecraft is protected during launch by a nose fairing with a launch escape system, which is jettisoned once the vehicle exits the dense layers of the atmosphere. Soyuz MS is highly automated; its Kurs system enables automatic rendezvous and docking with the ISS. Manual control is possible in the event of system failure.
Orbital module
The forward-most section of the spacecraft is the orbital module (Russian: Бытовой отсек (БО), romanized: Bitovoy Otsek (BO), or habitation module). It provides more living space than the descent module and includes a toilet. It has three hatches: a forward hatch for docking with the ISS, a side hatch for crew ingress and egress during ground operations, and an aft hatch connecting to the descent module. In principle, the side hatch could be used for spacewalks by sealing the other hatches and using the module as an airlock, although this capability has never been used on the MS variant due to the availability of larger dedicated airlocks on the ISS. In microgravity, the orbital module's conceptual orientation differs from that of the reentry module, with crew members positioned with their heads toward the forward docking port. The module has a small forward-facing window which can be used during manual docking if the automated system fails. A crew member observes the approach from this window and relays information to the commander, who pilots the spacecraft from the reentry module using a periscope mounted on the midsection of the spacecraft. The module can accommodate over 100 kilograms (220 lb) of cargo at launch and is typically filled with up to 170 kilograms (370 lb) of waste before being jettisoned prior to re-entry where it will burn up in the atmosphere. The orbital module can be customized for specific mission requirements without affecting the safety-critical systems of the descent module. Compared to earlier Soyuz versions, it incorporates additional anti-meteoroid shielding.
Descent module
The central section is the descent module (Russian: Спускаемый аппарат (СА), romanized: Spuskaemiy Apparat (SA)), which houses the crew during launch and return. During re-entry it is shielded by a heat-resistant covering and slowed using atmospheric drag and parachutes. At one metre (3 ft 3 in) above ground, solid-fuel landing engines behind the heat shield fire to cushion the final impact. The reentry module is designed for high volumetric efficiency (internal volume relative to hull surface area). A spherical shape would be optimal but offers no lift, resulting in a fully ballistic reentry, which is difficult to steer and subjects the crew to high g-forces. Instead, the Soyuz uses a compromise "headlight" shape: a hemispherical forward section, a shallow conical midsection, and a spherical heat shield, allowing limited lift and steering. The nickname derives from the resemblance to early sealed beam automotive headlights.
Instrumentation/propulsion module
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