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Soyuz MS

Soyuz MS
Союз МС
Soyuz MS-20 approaching the ISS
ManufacturerEnergia
Country of originRussia
OperatorRoscosmos
Specifications
Spacecraft typeHuman spaceflight
Launch mass7,290 kg (16,070 lb)
Payload capacity
  • Launch: Crew + 170 kg (370 lb)
  • Landing: Crew + 60 kg (130 lb)
  • Disposal: 170 kg (370 lb)
Crew capacity3
Volume
  • Total: 10 m3 (350 cu ft)
  • Descent module: 4 m3 (140 cu ft)
  • Orbital module: 6 m3 (210 cu ft)
Batteries755 Ah
RegimeLow Earth orbit
Design life200 days when docked to the International Space Station (ISS)
Dimensions
Solar array span10.7 m (35 ft)
Width2.72 m (8 ft 11 in)
Production
StatusActive
On order3
Built26
Launched26 (as of 11 September 2024)
Operational1 (MS-26)
Retired24
Failed1 (MS-10)
Maiden launch7 July 2016 (MS-01)
Last launchActive
Related spacecraft
Derived fromSoyuz TMA-M
Flown withSoyuz FG (2016–2019)
Soyuz 2.1a (2020–)
← Soyuz TMA-M Orel

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," reflecting upgrades primarily focused on the communications and navigation subsystems. An evolution of the Soyuz TMA-M spacecraft, the Soyuz MS features minimal external changes, mainly in the placement of antennas, sensors, and thrusters. It is used by Roscosmos for human spaceflight missions.

Soyuz MS-01 conducted its maiden flight on 7 July 2016, heading to the International Space Station (ISS). The mission included a two-day checkout phase to validate the spacecraft’s new design before docking with the ISS on 9 July 2016. After remaining docked to the ISS for 113 days, the crew of MS-01 returned to Earth on 30 October 2016, safely landing on the Kazakh Steppe.

The spacecraft has experienced one in-flight abort during the Soyuz MS-10 mission. Shortly after the four boosters of its Soyuz FG carrier rocket separated, one collided with its core stage. The spacecraft’s onboard computer activated the launch escape system, which performed flawlessly, quickly pulling the reentry and orbital modules away from the failing rocket. Once at a safe distance, the system jettisoned the reentry module, allowing it to descend to the ground under parachutes. The crew landed unharmed.

Design

Exploded plan of the Soyuz MS spacecraft and Soyuz FG rocket

Like all previous variants, the Soyuz MS spacecraft consists of three parts (from forward to aft in space and top to bottom when mounted on a rocket):

The orbital and descent modules contain the pressurized habitable living space. By moving as much equipment and space as possible into the orbital module, which does not have to be shielded or decelerated during re-entry, the Soyuz three-part craft is larger and lighter than two-part designs. By comparison, the Apollo spacecraft's pressurized command module provided a crew of three six cubic metres (210 cu ft) of living space and had a reentry mass of 5,000 kilograms (11,000 lb); while the Soyuz MS provides the same crew with ten cubic metres (350 cu ft) of living space while the reentry module weighs 2,950 kilograms (6,500 lb).

Soyuz can carry up to three cosmonauts and provide life support for them for about 30 person-days. The life support system provides a nitrogen/oxygen atmosphere at sea level partial pressures. The atmosphere is regenerated through KO2 cylinders, which absorb most of the CO2 and water produced by the crew and regenerates the oxygen, and LiOH cylinders which absorb leftover CO2. Estimated deliverable payload weight is up to 200 kg and up to 65 kg can be returned.[1]

The vehicle is protected during launch by a nose fairing with a launch escape system, which is jettisoned after passing through the atmosphere. The spacecraft is highly automated, and its Kurs system is capable of navigating to an automatic docking at the ISS. However, a pilot can operate the spacecraft independently of ground control if necessary.

Orbital module

Drawing highlighting the orbital module

The forward-most section of the spacecraft is the orbital module (Russian: Бытовой Отсек [БО], romanized: Bitovoy Otsek [BO]), also referred to as the habitation module.

The module features three ports. The forward port is used for docking with the ISS, the side port is used for crew entry during ground operations and potential spacewalks, and the aft port connects to the reentry module.

Designed for multiple purposes, the orbital module provides living space for the crew while in orbit, including a toilet and additional room compared to the confined reentry module. It can hold over 100 kilograms (220 lb) of cargo during launch. Since the module is jettisoned and destroyed before reentry, it is typically packed with up to 170 kilograms (370 lb) of waste before being sealed off.

The modular design enables customization for specific missions without compromising the critical systems of the reentry module. In zero gravity, the module’s orientation differs from the reentry module's, with cosmonauts standing or sitting with their heads toward the docking port.

The orbital module of the Soyuz MS includes a small forward-facing window, which allows the crew, particularly the flight engineer, to assist the commander with manual docking if automated systems fail.

A hatch between the orbital and descent modules can be sealed, allowing the orbital module to serve as an airlock. Cosmonauts could theoretically exit through the side port, though this feature has never been used, as the ISS provides larger, dedicated airlocks. The side port is the crew’s entry point when boarding the spacecraft on the launch pad.

Compared to previous versions, the orbital module of the Soyuz MS has additional anti-meteoroid shielding.[2]

Descent module

Drawing highlighting the descent module

The mid-section of the spacecraft is the reentry module (Russian: Спускаемый Аппарат [СА], romanized: Spuskaemiy Apparat [SA]). It is where the crew is seated for launch and the journey back to Earth. It is covered by a heat-resistant covering to protect it during re-entry. It is slowed initially by the atmosphere, then by a braking parachute, followed by the main parachute, which slows the craft for landing. At one meter above the ground, solid-fuel braking engines mounted behind the heat shield are fired to give a soft landing. One of the design requirements for the reentry module was for it to have the highest possible volumetric efficiency (internal volume divided by hull area). The best shape for this is a sphere, but such a shape can provide no lift, which results in a purely ballistic reentry. Ballistic reentries are hard on the occupants due to high deceleration and can't be steered beyond their initial deorbit burn. That is why it was decided to go with the "headlight" shape that the Soyuz uses — a hemispherical forward area joined by a barely angled conical section (seven degrees) to a classic spherical section heat shield. This shape generates a small amount of lift due to the unequal weight distribution. The nickname was coined when nearly every automobile headlight was a circular paraboloid.

Instrumentation/propulsion module

Drawing highlighting the instrumentation/propulsion module

The aft-most section of the spacecraft is the instrumentation/propulsion module (Russian: Приборно-Агрегатный Отсек [ПАО], romanized: Priborniy-Agregatniy Otsek [PAO]), also referred to as the service module or aggregate compartment. It is subdivided into three main sections: the intermediate compartment, the instrumentation compartment, and the propulsion compartment.

The instrumentation compartment (Russian: Приборно Отсек [ПО], romanized: Priborniy Otsek [PO]), is a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range communications, telemetry, and instruments for orientation and control. The propulsion compartment (Russian: Агрегатный Отсек [АО], romanized: Agregatniy Otsek [AO]), a non-pressurized part of the service module, contains the main engine and a spare: liquid-fuel propulsion systems for maneuvering in orbit and initiating the descent back to Earth. The spacecraft also has a system of low-thrust engines for orientation, attached to the intermediate compartment (Russian: Переходной Отсек [ПхО], romanized: Perekhodnoi Otsek [PkhO]). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the sun by rotating the spacecraft.

Re-entry procedure

Soyuz MS-02 at the moment of touchdown. The orange glow and dust cloud can be seen around the descent module as the soft-landing engines fire. The spacecraft lands under one main parachute.

Because its modular construction differs from that of previous designs, the Soyuz has an unusual sequence of events prior to re-entry. The spacecraft is turned engine-forward and the main engine is fired for de-orbiting fully 180° ahead of its planned landing site. This requires the least propellant for re-entry, the spacecraft traveling on an elliptical Hohmann orbit to a point where it will be low enough in the atmosphere to re-enter.

Early Soyuz spacecraft would then have the service and orbital modules detach simultaneously. As they are connected by tubing and electrical cables to the descent module, this would aid in their separation and avoid having the descent module alter its orientation. Later, the Soyuz spacecraft detaches the orbital module before firing the main engine, which saves even more propellant and enables the descent module to return more payload. The orbital module cannot remain in orbit as an addition to a space station, as the hatch, which enables it to function as an airlock, is part of the descent module.

The parachute system is activated at an altitude of about 10 kilometres (6.2 mi). Two pilot parachutes deploy first, followed by a drogue chute that slows the spacecraft from 230 to 80 metres per second (830 to 290 km/h; 510 to 180 mph). The main parachute then deploys, further reducing the descent rate to 7.2 metres per second (26 km/h; 16 mph). The heat shield is jettisoned at an altitude of about 5.8 kilometres (3.6 mi), revealing six solid-propellant soft-landing motors that fire just 1 metre (3.3 ft) above the ground, slowing the descent rate to less than 2 metres per second (7.2 km/h; 4.5 mph). The seats inside the descent module, which are fitted with shock absorbers and liners custom molded to each crew member's body shape, cushion the final impact.[3]

Soyuz missions typically land in the evening so that recovery helicopters can more easily see the spacecraft as it descends in the twilight, illuminated by the sun when it is above the shadow of the Earth. Since the beginning of Soyuz missions to the ISS, only five have performed nighttime landings.[4]

Soyuz MS improvements

Soyuz MS-02 being prepared for launch in September 2016
Soyuz MS-05 docked to the Rassvet module during Expedition 53

The Soyuz MS received the following upgrades with respect to the Soyuz TMA-M:[5][6][7][8]

  • Apparatus for Satellite Navigation (ASN-K, Russian: Аппаратура Спутниковой Навигации [АСН-К], romanized: Apparatura Sputnikovoi Navigatsii): Instead of relying on six ground stations to determine its orbital path, the new ASN-K will use GLONASS and GPS signals. Compared to the prior system, ASN-K is far less bulky and can be used to locate the Soyuz descent capsule on the ground after landing. It uses four fixed antennas to achieve a positioning accuracy of 5 m (16 ft) and aims to reduce that number to as little as 3 cm (1.2 in) and to achieve an attitude accuracy of 0.5°.[7]
  • New Kurs-NA rendezvous system: The new Kurs-NA (Russian: Курс-Новая Активная, romanized: Kurs-Novaya Aktivnaya, lit.'Course-New Active') automatic docking system is designed and manufactured in Russia, replacing its Ukrainian predecessor. This change addresses a political problem (with the two countries at war) and enhances the system’s capabilities with a higher level of computerization. While the original Kurs system was highly reliable over the years, many of its electronic components have become outdated. The Kurs-NA is 25 kg (55 lb) lighter, 30% smaller, and consumes 25% less power. Additionally, it features a single phased-array antenna, replacing four antennas on the older system, while the two narrow-angle antennas have been retained although re-positioned further toward the rear. To assist with docking, the old halogen headlight has been replaced with a brighter, more energy-efficient LED light.[9][10]
  • Unified Command and Telemetry System (EKTS, Russian: Единая Командно-Телеметрическая Система, romanized: Edinaya Komandno-Telemetricheskaya Sistema): Instead of solely relying on ground stations in Russian territory, the spacecraft has a satellite-capable communications system, EKTS, that connects to Russia's Luch system, providing coverage 83 percent of the day. It also retains very high frequency (VHF) and ultra high frequency (UHF) radios for communications with ground stations. The large EKTS S-band satellite antenna array, one of the most prominent new features on the ship's exterior, is also capable of communicating via American TDRS and Europe's EDRS satellites. The EKTS integrates several previous systems, including the BRTS (radio), MBITS (telemetry), and Rassvet (radio voice), which have been replaced or upgraded for compatibility. Additionally, it features a COSPAS-SARSAT transponder for real-time location tracking during reentry and landing. These changes enable the Soyuz to use the same ground segment terminals as the Russian Segment of the ISS.[11]
  • Re-arranged attitude control thrusters: the Integrated Propulsion System (Russian: Комбинированная Двигательная Установка, romanized: Kombinirovannaya Dvigatelnaya Ustanovka [KDU]) was reconfigured provide full redundancy between two independent propellant manifold loops, supplying oxidizer and fuel to 14 pairs of high-thrust attitude control engines (eight pairs of large and six pairs of small thrusters). With each thruster pair connected to a different manifold, this arrangement significantly enhanced system reliability. Additionally, the number of aft-facing thrusters was doubled, providing crucial backup in case of main engine failure. To complement these hardware modifications, the avionics unit was redesigned, and the EFIR, responsible for tracking propellant consumption, was redesigned to prevent inaccurate readings.[12]
  • Improved docking mechanism: The docking system received a backup electric driving mechanism.[13]
  • SZI-M reusable black box: A new black box, the SZI-M (Russian: Система Запоминания Информации [СЗИ-М], romanized: Sistema Zapominaniya Informatsii, lit.'Information Storage System') black box is installed beneath the commander's seat in the descent module. Designed and manufactured in Russia, this device records voice and data throughout the mission. With a capacity of 4 GB and a recording speed of 256 Kb/s, the SZI-M is designed to withstand extreme conditions. It can tolerate falls of 150 m/s and temperatures of 700°C for 30 minutes and is rated for 100,000 overwrite cycles. It can be reused on up to ten missions.[14][15]
  • Power system improvements: To support the increased energy consumption from the improved electronics, a fifth battery with a 155 amp-hour capacity was added, and the cell efficiency on the solar panels improved to 14% (from 12%), and the collective area increased by 1.1 m2 (12 sq ft).[16]
  • Additional micro-meteoroid protection: Additional anti-micro-meteoroid shielding was added to the habitation module walls, largely at NASA's request. This measure was designed to safeguard the spacecraft's most vulnerable component against the unlikely but potential threat of a meteoroid or space debris impact.[16]
  • Digital camera system: The spacecraft utilizes a digital television camera system based on MPEG-2, replacing the older analog system. This upgrade enables space-to-space RF communication between the spacecraft and the station and reduces interference.[17]

List of flights

References

  1. ^ "Транспортный пилотируемый корабль "Союз ТМ"".
  2. ^ Zak, Anatoly (15 November 2024). "Soyuz-MS spacecraft". RussianSpaceWeb.com. Retrieved 23 November 2024.
  3. ^ "Way back to Earth". www.esa.int. Retrieved 6 October 2024.
  4. ^ "Soyuz Trio set for rare Nighttime Landing on Friday – ISS Expedition 45".
  5. ^ Zak, Anatoly (5 July 2016). "Russia's Workhorse Soyuz Space Taxi Gets a Makeover". Popular Mechanics. Retrieved 6 July 2016.
  6. ^ Zak, Anatoly (8 July 2016). "Soyuz MS spacecraft". RussianSpaceWeb.com. Retrieved 6 July 2016.
  7. ^ a b Krasilnikov, A. (2015). Новая модификация "Союза" полетит через год [A new version of the Soyuz to flight this year] (in Russian). Novosti Kosmonavtiki. Retrieved 9 July 2016.
  8. ^ Navias, Rob (8 July 2016). The New, Improved Soyuz Spacecraft. Space Station Live. NASA JSC. Retrieved 9 July 2016 – via YouTube. Public Domain This article incorporates text from this source, which is in the public domain.
  9. ^ Zak, Anatoly (8 July 2016). "The Kurs-NA docking system for Soyuz MS". RussianSpaceWeb.com. Retrieved 9 July 2016.
  10. ^ Harding, Pete (28 July 2012). "Progress M-15M re-docks to ISS following resolution of Kurs-NA failure". NASASpaceFlight (not associated with NASA). Retrieved 1 September 2012.
  11. ^ Zak, Anatoly (7 July 2016). "The EKTS communications system for Soyuz MS spacecraft". RussianSpaceWeb.com. Retrieved 6 July 2016.
  12. ^ Zak, Anatoly (7 July 2016). "Propulsion system for the Soyuz MS spacecraft". RussianSpaceWeb.com. Retrieved 6 July 2016.
  13. ^ Zak, Anatoly (3 July 2016). "Soyuz rocket flies critical test mission with Progress-MS". RussianSpaceWeb.com. Retrieved 6 July 2016.
  14. ^ Для нового корабля "Союз-МС" создали многоразовый "черный ящик" [New reusable black box for the Soyuz MS] (in Russian). Ria Novosti. 30 June 2016. Retrieved 9 July 2016.
  15. ^ Zak, Anatoly (7 July 2016). ""Black Box" for the Soyuz MS spacecraft". RussianSpaceWeb.com. Retrieved 6 July 2016.
  16. ^ a b Zak, Anatoly (6 July 2016). "Power for Soyuz MS spacecraft". RussianSpaceWeb.com. Retrieved 6 July 2016.
  17. ^ "Launch vehicle with Soyuz MS spacecraft is on the launch pad". Energia. 4 July 2016. Retrieved 6 July 2016.
  18. ^ "First Soyuz MS flies". www.russianspaceweb.com.
  19. ^ "Soyuz MS-07 to carry fresh crew to ISS". www.russianspaceweb.com.
  20. ^ "Грузовой корабль "Прогресс" полетит к МКС по сверхбыстрой схеме". 20 March 2020.
  21. ^ @roscosmos (20 January 2022). "В случае подписания между Роскосмосом и @NASA соглашения о «перекрестных» полетах на МКС Анну Кикину планируется вв…" (Tweet) – via Twitter.
  22. ^ a b "Russia to launch new Soyuz capsule to replace leaky spacecraft on space station". Space.com. 11 January 2023. Retrieved 16 January 2023.