European Service Module

The European Service Module (ESM) is the service module component of the Orion spacecraft, serving as its primary power and propulsion component until it is discarded at the end of each mission. In January 2013, NASA announced that the European Space Agency (ESA) will contribute the service module for Artemis I, based on the ESA's Automated Transfer Vehicle (ATV). It was delivered by Airbus Defence and Space in Bremen, in northern Germany to NASA at the end of 2018. After approval of the first module, the ESA will provide the ESMs from Artemis II to Artemis VI.

European Service Module

The ESM is visible at left as Orion approaches the Moon on the Artemis I mission
Manufacturer	Airbus Defence and Space
Designer	ESA
Operator	NASA
Dimensions
Height	4 m (13 ft)[1]
Diameter	4.1 m (13 ft 5 in) excluding solar panels 5.2 m (17 ft 1 in) with solar panels stowed 19 m (62 ft 4 in) with solar panels deployed
Production
Status	Operational
Maiden launch	November 16, 2022 (Artemis I)
Related spacecraft
Derived from	Automated Transfer Vehicle
Flown with	Orion
Propulsion
Propellant mass	8,600 kg (19,000 lb)[2][3]
Powered by	1 × AJ10 8 × R-4D
Maximum thrust	AJ10: 26.6 kN (6,000 lbf) R-4D: 3.92 kN (880 lbf)
Propellant	MON-3/MMH

The module's first flight was Artemis I, the first major milestone in NASA's Artemis program to return humans to the Moon, on November 16, 2022. The Space Launch System launched Orion toward the Moon, where the ESM placed the spacecraft into distant retrograde orbit around the Moon, and subsequently extracted it from that orbit and sent it back to Earth.

The service module (SM) supports the crew module (CM) from launch through to separation prior to reentry. It provides in-space propulsion capability for orbital transfer, attitude control, and high altitude ascent aborts. It provides the water and oxygen needed for a habitable environment, generates and stores electrical power, and maintains the temperature of the vehicle's systems and components. This module can also transport unpressurized cargo and scientific payloads.^[4]

History

Initial design

Pre-ATV service module design

Roughly cylindrical in shape, the original American-designed Orion SM, like the CM, would have been constructed of Al-Li alloy (to keep weight down), and would have featured a pair of deployable decagonal solar panels, similar in design to the panels used on the Mars Phoenix lander. The panels, the first to be used on a U.S. crewed spacecraft (except for a 10-year period, the Soviet/Russian Soyuz spacecraft has used them since the first mission in 1967), would allow NASA to eliminate the need to carry malfunction-prone fuel cells, and their associated hardware (mainly liquid H₂ tanks) in the SM, resulting in a shorter and more maneuverable spacecraft. Successful initial testing of an Orion solar array design using full-scale "UltraFlex wing" hardware was reported in October 2008.^[5]

The Orion Main Engine (OME) was a 33-kilonewton (7,500 lbf) thrust, pressure-fed, regeneratively cooled, storable bi-propellant rocket engine to be made by Aerojet. The OME was an increased performance version of the 27-kilonewton (6,000 lbf) thrust rocket engine used by the Space Shuttle for its Orbital Maneuvering System. The SM Reaction Control System (RCS), the spacecraft's maneuvering thrusters (originally based on the Apollo "quad" system, but resembling that used on its predecessor, Gemini), would also be pressure-fed, and would use the same propellants. NASA believed the SM RCS would be able to act as a backup for a trans-Earth injection burn in case the main SM engine failed.

A pair of liquid oxygen tanks (similar to those used in the Apollo service module) would provide, along with small tanks of nitrogen, the crew with breathing air at sea-level or "cruising altitude" pressure (1 or 0.7 atm), with a small "surge tank" providing necessary life support during reentry and touchdown. Lithium hydroxide (LiOH) cartridges would recycle the spacecraft's environmental system by "scrubbing" the carbon dioxide (CO₂) exhaled by the astronauts from ship's air and adding fresh oxygen and nitrogen, which was then cycled back out into the system loop. Because of the switch from fuel cells to solar panels, the service module would have an onboard water tank to provide drinking water for the crew, and (when mixed with glycol), cooling water for the spacecraft's electronics. Unlike the practice during Apollo of dumping both water and urine overboard during the flight, the Orion would have an onboard recycling system, identical to that used on the International Space Station, to convert both waste water and urine into both drinking and cooling water.

The service module also mounted the spacecraft's waste heat management system (its radiators) and the aforementioned solar panels. These panels, along with backup batteries located in the Orion CM, would provide in-flight power to the ship's systems. The voltage, 28 volts DC, was similar to that used on the Apollo spacecraft during flight.

The Orion SM would be encapsulated by fiberglass shrouds jettisoned at the same time as the LES/Boost Protective Cover, which would take place roughly 21⁄2 minutes after launch (30 seconds after the solid rocket first stage was jettisoned). Prior to the "Orion 606" redesign, the Orion SM resembled a squat, enlarged version of the Apollo service module. The "Orion 606" SM design retained the 5-meter (16 ft) width for the attachments of the Orion SM with the Orion CM, but used a Soyuz-like service module design to allow Lockheed Martin to make the vehicle lighter in weight and permitting the attachment of the decagonal solar panels at the module's midpoints, instead of at the base near the spacecraft/rocket adapter, which might have subjected the panels to damage.

The Orion service module (SM) was projected comprising a cylindrical shape, having a diameter of 5 m (16 ft) and an overall length (including thruster) of 4.78 m (15 ft 8 in). The projected empty mass was 3,600 kg (8,000 lb), fuel capacity was 8,200 kg (18,000 lb).^[6][7]

Cost reviews and scope changes

A review of the Constellation program in 2009 by the new Augustine Commission prompted by the then new Obama administration had found that five years in, the service module development program was already running four years behind its 2020 lunar target and was woefully underfunded. The only element worth continuing was the Crew Exploration Vehicle in the role of a space station escape capsule.^[8] This led in 2010 to the Administration cancelling the program by withdrawing funding in the proposed 2011 budget. A public outcry led to the program being frozen rather than outright cancelled and a review launched in to how costs could be cut, which found that it was possible to continue if there was an emphasis on finding alternate funding, reducing the complexity by narrowing the scope to focus on the Moon and deep space rather than Mars, and by reusing existing hardware, reducing the range of equipment requiring development. The Ares I launcher intended for crew flights had significant design issues such as being overweight and prone to dangerous vibration, and in the case of a catastrophic failure its blast radius exceeded the escape system's ejection range.^{[citation needed]} Its role as the Orion launch vehicle was replaced by the Space Launch System, and the three different Crew Exploration Vehicle designs were merged in to a single Multipurpose Crew Exploration Vehicle.

European ATV-based module

Edoardo Amaldi ATV approaching the International Space Station in 2012

In May 2011, the European Space Agency's (ESA) director general announced a possible collaboration with NASA to work on a successor to ESA's Automated Transfer Vehicle (ATV).^[9] ESA's provision of this successor could be counted towards its 8% share of the operating costs of the International Space Station (ISS); the ATV missions resupplying the station only covered this obligation up to 2017. On 21 June 2012, Astrium announced that it had been awarded two separate studies to evaluate possible future missions building on the technology and experience gained from its development of ATV and the Columbus laboratory. The first study looked into the construction of a service module which would be used in tandem with the Orion capsule.^[10] The second examined the production of a versatile multi-purpose orbital vehicle. Each study was worth €6.5 million.^[11]

In November 2012, ESA obtained the commitment of its member states for it to construct an ATV-derived service module for Orion, to fly on the maiden flight of the Space Launch System, thereby meeting ESA's budgetary obligation to NASA regarding the ISS for 2017–2020.^[12] No decision was made about supplying the module for later Orion flights.^[13]

In January 2013, NASA announced its agreement, made the preceding December, that ESA would build the service module for Exploration Mission-1 (renamed Artemis I), then scheduled to take place in 2017. This service module was not required for Exploration Flight Test-1 in 2014, as this used a test service module supplied by Lockheed Martin.^[14] On 17 November 2014 ESA signed a €390 million fixed price contract with Airbus Defence and Space for the development and construction of the first ATV-based service module.^[15] In December 2016, ESA's member states agreed it would extend its commitment to the ISS to 2024, and would supply a second service module, as part of the resulting budgetary obligation.^[16]

Design

Service module shown with the crew module, adapters, and fairing panels

The new design^[17] is approximately 5.0 meters (16.5 ft) in diameter and 4.0 meters (13 ft) in length, and made of aluminium-lithium alloy.^[18]

Looking up from beneath the ESM for the Artemis II mission showing its single AJ10 main engine and eight R-4D secondary engines

The service module's main engine for Artemis I was a Space Shuttle Orbital Maneuvering System (OMS) AJ10-190 engine left over from the Space Shuttle program,^[17] in which it flew on 19 missions and carried out 89 burns.^[18] It is intended that the OMS will be used for the first three (or five^[19]) service modules and four alternate engine designs are under consideration for later flights, thought to include the AJ10-118k; used for the second stage of the Delta II it is a lighter and more powerful version in the same AJ10 engine family whose lineage began with the Vanguard.^[20]

In comparison with the Apollo command and service module, which previously took astronauts to the Moon, the European Service Module (ESM) generates approximately twice as much electricity (11.2 kW vs 6.3 kW), weighs nearly 40% less when fully fueled (15,461 kg,^[21] vs 24,520 kg) and is roughly the same size (4 m in length excluding engine^[22] and 4.1 m vs 3.9 m in diameter) supporting the environment for a slightly (45%) larger habitable volume on the crew module (8.95 m³ vs 6.17 m³) though it will carry 50% less propellant for orbital maneuvers (8,600 kg usable propellant vs 18,584 kg).

The ESM will be able to support a crew of four for 21 days which exceeds the 14 day endurance for the three-man Apollo.

The new design for the solar arrays, replacing ATK's decagonal (labeled "circular") UltraFlex design,^[23] is by Airbus Defence and Space,^[18] whose subsidiary, Airbus Defence and Space Netherlands (then known as Dutch Space), built the ATV's X-shaped array of four panels. The ATV's array was expected to generate 4.6 kilowatts. The upgraded version for the service module will generate about 11 kilowatts,^[23] and will span about 19 m (62 ft) when extended.^[18]

In September 2015, Thales Alenia Space signed a contract with Airbus Defence and Space to develop and produce thermomechanical systems for the service module, including structure and micrometeoroid protection, thermal control and consumable storage and distribution.^[24]

Lockheed Martin is building the two adapters, connecting the service module to the crew module and to the upper stage of the Space Launch System, and also the three fairing panels that are jettisoned after protecting the service module during launch and ascent.^[18]

From 2017

The ESM for the Artemis II mission inside the O&C building after testing in 2023

On 16 February 2017 a €200m contract was signed between Airbus and the European Space Agency for the production of a second European service module for use on the first crewed Orion flight.^[25]

On 26 October 2018 the first unit for Artemis I was assembled in full at Airbus Defence and Space's factory in Bremen.^[26]

In November 2019, ESA member states approved the financing of ESMs for Artemis III and IV.^[27] In May 2020 the contract between Airbus and the European Space Agency for the production of a third European Service Module was signed.^[28]

In October 2020, ESA and NASA sign a memorandum of understanding which includes the provision by ESA of ESM-4 and ESM-5 as a participation in the Gateway space station, allowing three flights of European astronauts to Lunar orbit between 2025 and 2030.^[29]

In February 2021, the contract between Airbus and the European Space Agency to provide ESM-4 to ESM-6 was signed.^[30]

Specifications

Length	4 m (13 ft 1 in)
Diameter	4.1 m (13 ft 5 in) excluding solar panels 5.2 m (17 ft 1 in) with solar panels stowed 19 m (62 ft 4 in) with solar panels deployed[2]
Primary engine	1 × Aerojet AJ10 providing 26.6 kN (6,000 lbf) of thrust (ESM-1 to ESM-6)[2] 1 × Aerojet Orion Main Engine (from ESM-7 on)[31]
Secondary engines	8 × Aerojet R-4D providing 490 N (110 lbf) of thrust each, 3.92 kN (880 lbf) total[2]
Maneuvering thrusters	24 × Airbus Reaction Control System engines in six pods of four providing 220 N (49 lbf) of thrust each, 5.28 kN (1,190 lbf) total[2]
Propellant capacity	9,000 kg (20,000 lb)[1] of propellant in four 2,000 L (440 imp gal; 530 US gal) (two MON and two MMH). Usable load is 8,600 kg (19,000 lb).[2][3]
Power generation	11.2 kW from 4 x 7.375 m (24.20 ft) wings each containing 3 solar panels[1]
Total launch mass	13,500 kg (29,800 lb) for Lunar Mission, including 240 kg (530 lb) of water in four tanks, 90 kg (200 lb) of oxygen in three tanks, 30 kg (66 lb) of nitrogen in one tank[2]
Payload	Payload mass up to 380 kg (840 lb) and a payload volume of up to 0.57 m3 (20 cu ft)[3]
Materials	Aluminum alloy (structure), stainless steel, titanium (tanks), Kapton (insulation) and copper (electrical and mechanical components)[32]

European Service Module models

Model	Mission	Status	Framework
STA	Structural Test Article	Used for structural testing in Plum Brook Station, Ohio
PQM	Propulsion Qualification Model	Used for propulsion testing in White Sands, New Mexico
ESM-1 Bremen	Artemis I	Mission complete, launched 16 November 2022	ISS barter
ESM-2	Artemis II	Delivered to NASA, in O&C, awaiting flight	ISS barter
ESM-3	Artemis III	Delivered to NASA, in O&C[33]	ISS barter
ESM-4	Artemis IV	Undergoing integration in Bremen, delivery to NASA planned for 2025.	Gateway
ESM-5	Artemis V	Undergoing integration in Bremen	Gateway
ESM-6	Artemis VI	Undergoing integration in Bremen	ISS barter
ESM-7 to 9	Artemis VII to IX	Production in negotiation between ESA and Airbus	ISS barter

References

1. European Service Module test article 2015
2. Orion / EM-1 (Exploration Mission-1) Aug 2019
3. "Artemis 1".
4. "Explore the Exploration Vehicle". NASA. 6 June 2013. Archived from the original on 6 May 2021. Retrieved 6 February 2021. This article incorporates text from this source, which is in the public domain.
5. "NASA and ATK Successfully Deploy 18-Foot Diameter Solar Array for ST8 Program". ATK. 9 October 2008.
6. "The Orion Service Module". NASA. 4 August 2008. Archived from the original on 13 August 2009. Retrieved 2008-08-19.
7. "Orion". Encyclopedia Astronautica. Archived from the original on December 28, 2016. Retrieved 2013-05-11.
8. Augustine, Norman; Austin, Wanda; Bejmuk, Bohdan; Chiao, Leroy; Chyba, Christopher; Crawley, Edward; Greason, Jeffrey; Kennel, Charles; Lyles, Lester; Ride, Sally (October 22, 2009). "Final Report" (PDF). Review of United States Human Space Flight Plans Committee. Archived from the original (PDF) on February 16, 2019. Retrieved August 26, 2022.
9. "US and Europe plan new spaceship". BBC News. 5 May 2011. Archived from the original on 6 May 2011. Retrieved 2011-05-14.
10. "ATV evolution studies look at exploration, debris removal". Spaceflight Now. 21 June 2012. Retrieved 2012-06-23.
11. "Astrium awarded two ATV evolution studies from ESA". Astrium. 21 June 2012. Archived from the original on 3 April 2013. Retrieved 2012-06-23.
12. Bergin, Chris (November 21, 2012). "UK steps up, as ESA commit to ATV Service Module on NASA's Orion". NASASpaceFlight.com. NASA. Retrieved 2013-05-06.
13. Clark, Stephen (November 21, 2012). "ESA member states fund Orion service module". Spaceflight Now. Retrieved 2013-05-06.
14. "NASA Signs Agreement for a European-Provided Orion Service Module – NASA". 2013-01-16. Retrieved 2024-05-15.
15. "ESA Commissions Airbus Defence and Space as Prime Contractor for US Space Capsule Orion Service Module". spaceref business. 17 November 2014. Archived from the original on 12 May 2021. Retrieved 18 November 2014.
16. de Selding, Peter B. (2 December 2016). "Europe commits to the space station and ExoMars as part of $11 billion in commitments to ESA". Space News. Retrieved 7 December 2016.
17. Bergin, Chris (20 June 2015). "Plum Brook prepped for EM-1 Orion Service Module testing". NASASpaceFlight.com. Retrieved 28 July 2015.
18. Garcia, Mark (17 June 2015). "NASA Gears Up to Test Orion's Powerhouse". NASA. Retrieved 28 July 2015.
19. "Engine of Atlantis". Moon Daily. Retrieved 2024-05-15.
20. Coppinger, Rob (2017-02-23). "ESA deal hinges on what Trump does with NASA's human spaceflight plans". SpaceNews. Retrieved 2024-05-15.
21. "Orion (MPCV)".
22. Apollo Operators Handbook Block II Spacecraft (PDF). Vol. 1. NASA. 15 April 1969. p. 60.
23. Leone, Dan (1 August 2013). "Ousted from First Orion Flight, Circular ATK Solar Arrays Still Set To Power Cygnus". Space News. Retrieved 28 July 2015.
24. "Thales Alenia Space to supply thermomechanical systems for Orion ESM". 17 September 2015.
25. ""Airbus Defence and Space Wins 100 Million Euros ESA Contract for Second Service Module for NASA's Orion Crewed Space Capsule" Feb 2017". Archived from the original on 2017-04-19. Retrieved 2017-04-18.
26. "Call for media: The European Service module meets Orion". European Space Agency. 26 October 2018.
27. "Earth observation, deep space exploration big winners in new ESA budget – Spaceflight Now". Retrieved 2024-05-15.
28. "European contract signed for Moon mission hardware". BBC News. 26 May 2020. Archived from the original on 2022-12-16.
29. "NASA, European Space Agency Formalize Artemis Gateway Partnership – NASA". Retrieved 2024-05-15.
30. "Three more service modules for Artemis to be built in Europe". www.esa.int. Retrieved 2024-05-15.
31. "Aerojet Rocketdyne Awarded NASA Contract for Orion Spacecraft Main Engine". 2021-09-21.
32. "Tanks for Orion flight model no. 2 delivered".
33. "One step closer to the moon". Airbus Defence & Space - LinkedIn page. Airbus Defence & Space. 2024-05-07. Retrieved 2024-05-07.

External links

• Orion Spacecraft at NASA Archived 2020-11-12 at the Wayback Machine
• Orion at ESA
• European Service Module at Airbus Defence and Space Archived 2016-10-18 at the Wayback Machine