Artemis-1 — formerly Orion / EM-1 (Exploration Mission-1)
In March 2018, NASA renamed the former Orion / EM-1 (Exploration Mission-1) to Artemis-1. Artemis-1 will be the first integrated test of NASA’s deep space exploration systems: the Orion spacecraft, Space Launch System (SLS) rocket and the ground systems at Kennedy Space Center in Cape Canaveral, Florida. The first in a series of increasingly complex missions, Artemis-1 will be an uncrewed flight test that will provide a foundation for human deep space exploration, and demonstrate our commitment and capability to extend human existence to the Moon and beyond. 1)
Orion EM-1, previously known as SLS-1 (Space Launch System-1) is NASA's first planned flight of the Space Launch System and the second uncrewed test flight of the Orion MPCV (Multi-Purpose Crew Vehicle). NASA, ESA, European and US Industry have teamed to develop the ORION spacecraft.
Under an agreement between NASA and ESA, ratified in December 2012, NASA’s new Orion vehicle for human space exploration missions includes the ESM (European Service Module), based upon the design and experience of ESA’s ATV (Automated Transfer Vehicle), the supply craft for the ISS (International Space Station).
ESA’s industrial prime contractor for ATV, Airbus Defence and Space of Bremen, Germany, is leading a European industrial consortium, developing this vehicle on behalf of ESA and working closely with NASA’s Orion US industrial prime contractor Lockheed Martin Space Systems.
Orion is the spacecraft that NASA intends to use to send humans and cargo into space beyond low earth orbit and to return them safely to Earth. It is being developed for crewed missions to cislunar space, asteroids, and then to Mars. The capsule is also planned as a backup vehicle for missions to the ISS (International Space Station). It will be launched by the NASA-developed SLS (Space Launch System) in 2019. 2) 3)
The first test flight of Orion was successfully completed in December 2014 with a Delta IV launch vehicle that launched the Orion Crew Module into a high elliptical orbit to demonstrate high-speed atmospheric Earth re-entry. This flight test did not include the ESM.
It is planned such that the Orion EM-1 flies a mission profile similar to what might be used in a future asteroid redirect mission. The un-crewed Orion travels to a lunar DRO (Distant Retrograde Orbit) mission (Figure 2), then returns on a trajectory calculated to achieve a high speed atmospheric entry on the order of ~11 km/s to demonstrate the performance and effectiveness of the Orion TPS (Thermal Protection System), as well as relevant environments prior to the first manned launch of the system. The total mission duration is 25 days (6 at destination). This will be the first flight of the ESM.
Orion EM-2 is planned as a Crewed High Lunar Orbit mission no later than the end of 2021. It is planned to spend several days in lunar orbit before performing a TEI (Trans-Earth Injection) burn to begin the return to Earth. The total mission duration is expected to be 14 days maximum (4 at destination).
Table 2: Overview of Orion ESM Design Reference Missions
Figure 1: Artist's rendition of the Orion EM-1 spacecraft in lunar orbit (image credit: NASA, ESA)
The Orion Vehicle
• CM (Crew Module)
• ESM (European Service Module)
• CMA (Crew Module Adapter)
• SA (Spacecraft Adapter)
• SAJ (Spacecraft Adapter Jettisoned Fairings)
• LAS (Launch Abort System)
The Service Module (SM) refers to the combined CMA + ESM + SA + SAJ.
The Crew Module and ESM (European Service Module), also referred to as SM, are physically interfacing via an interface ring called the CMA (Crew Module Adapter). The ESM is attached to the CMA for the duration of the mission. Just prior to the Earth’s orbit entry, the CMA separates from the CM for CMA/ESM disposal and the CM performs final reentry and landing operations.
NASA is responsible for development of the CM, CMA, SA, SAJ, and LAS elements of the Orion spacecraft. The CMA provides the structural, mechanical, electrical, and fluid interface between the CM and ESM. In addition, the CMA houses communication equipment, sublimators for thermal heat rejection, and power and data control/interface electronics. The SM is enclosed by three spacecraft adapter fairing panels (SAJ) which provide a partial load path from the CMA to SA but also protect the solar arrays, radiators, and thrusters from launch and ascent loads. The fairings will be jettisoned during the ascent phase or following main engine cut-off of the launch vehicle.
The SA (Spacecraft Adapter) provides the interface to the launch vehicle during launch. During launch and ascent, the ESM and SA will be enclosed by the SAJ. The SA attaches to the aft end of the ESM to the Launch Vehicle and includes the structural interface, separation mechanisms, and umbilical connectors for communication between the launch vehicle and the Orion Spacecraft. At launch vehicle burnout, the Orion Spacecraft separates from the SA at the ESM/SA separation plane.
Orion EM-1 CM (Crew Module)
The milestones for the Orion EM-1 mirror the path taken by the Orion EFT-1 (Exploration Flight Test-1) spacecraft. However, the Orion EM-1 will sport a number of improvements based on the experiences of the December 2014 test flight. NASA is beefing up the critical TPS (Thermal Protection System) that will protect astronauts from the searing heats experienced during reentry as the human rated vehicle plunges through the Earth’s atmosphere after returning from ambitious expeditions to the Moon and beyond.
Based in part on lessons learned from EFT-1, engineers are refining Orion’s heat shield to enhance the design, ease manufacturing procedures and significantly strengthen is heat resistant capabilities for the far more challenging space environments and missions that lie ahead later this decade and planned further out in the future as part of NASA’s agency-wide ‘Journey to Mars’ initiative to send humans to the Red Planet in the 2030s.
On all future flights starting with EM-1 (Exploration Mission-1), the Orion crew module must withstand the higher temperatures and speeds experienced during return from more distant destinations such as the Moon, near-Earth Asteroids and Mars. Orion's TPS is comprised of the 5 m diameter main heat shield covering the rounded base of the capsule as well as the grid of back shell tiles bonded around the vehicle from top to bottom. 7)
Starting with EM-1, engineers will bond Orion’s thermal protection system back shell tiles with a silver, metallic-based thermal control coating. The coating is designed to keep Orion’s back shell in a temperature range from approximately -65 to 290ºC prior to entry and afford protection against electrical surface charges in space and during reentry.
The pressure vessel is the primary structure of Orion’s crew module and is made of seven large aluminum pieces that must be welded together in detailed fashion. The first weld connected the tunnel to the forward bulkhead, which is at the top of the spacecraft and houses many of Orion’s critical systems, such as the parachutes that deploy during reentry. Orion’s tunnel, with a docking hatch, will allow crews to move between the crew module and other spacecraft. 8)
Orion’s pressure vessel is composed of seven large pieces of aluminum, three of which are the cone panels. The pressure vessel holds the atmosphere astronauts will breathe against the vacuum of deep space, forming the crew compartment. The three panels together form the angled mid-section around the crew module where the windows and hatch are located. While technicians have been joining other elements of the structure together since early September, the cone panels have presented a unique challenge for NASA and Lockheed Martin, the agency’s prime contractor for Orion. Engineers who have sought to reduce the crew module’s overall weight have encountered and overcome technical challenges. 9)
The lessons learned from the EFT-1 mission are being applied to the EM-1 (Exploration Mission-1) and EM-2 flight test configurations to optimize a system design that can smoothly transition into production.
Ten of the most important lessons from EFT-1 focused on the ability to evaluate the design with actual flight performance. This was critical for the remaining design process as NASA continues to develop the most advanced Human rated spacecraft ever built. The following are the top ten lessons learned from this test flight: 10)
1) Some deep space designs are classic for a reason: Every aspect of Orion’s design is driven by crew safety. Over 50 years of NASA’s investment learning the ins and outs of human spaceflight has provided direction for meeting deep space requirements. An example is LAS (Launch Abort System). About 6 minutes into launch, the LAS is jettisoned to save mass for the journey to deep space destinations. While other system configurations exist, design trade studies repeatedly highlighted the advantage of not carrying extra weight past the time it is needed. So because the Orion LAS supports missions to deep space, mass is king and any extra weight is an extreme hindrance to those missions. By shedding the Orion LAS early, this mass isn’t a burden to the vehicle for the entire mission, and other Orion systems are able to provide the abort function for the remainder of ascent to orbit.
2) Crew safety is built in, not bolted on: The EFT-1 tested and verified systems that are built “into the bones” of the spacecraft from the very beginning. This means not just the heat shield or the flight computers are designed for the rigors of deep space, but everything included in the fundamental systems and structure of the spacecraft are designed and built to specifications set forth by NASA. Every system design has a deep space requirement it is being built to right now: Orion’s seats are being designed to help prevent loss of consciousness as astronauts experience up to 5 G’s during high-velocity re-entries, the cooling system keeps the crew cabin about 25ºC despite its heat shield being heated to 2,200ºC during reentry, the built in stowage lockers are designed to double as a safe-haven during dangerous solar activity, the life support system allows for exercise since deep space missions require much longer stays in zero gravity, computers and avionics are designed to self-correct in case there is a failure and you’re months from home, and the crew module tiles are designed to protect from multiple micro-meteoroid strikes since the number of strikes will increase during missions that last months instead of days.
3) Reusability must be tied to reality: Part of flying for the first time in space is being able to make informed decisions about what we can realistically reuse following a deep space mission. After evaluating areas of water intrusion and corrosion, we’ve come to expect that many components in the crew module, especially inside the pressurized volume, or the hull where the crew sits, can be reused for later flights—components such as the computers, avionics and electrical distribution for example. The structure itself is more difficult to predict for reuse base on the unpredictable landing loads it might experience from a long journey from deep space with unpredictable landing sea conditions. The program is looking at options for reuse based on actual landing load data provided.
4) Designs mature as we Learn: Significant design changes are being made to optimize the EM vehicles. Thefuture design and analysis efforts will be simplified (Figure 5), overall mass has gone down, and recurring costs for production will be lowered. Establishing a common design philosophy has prevented a large number of engineering revisions and hardware changes. The Orion design is now incorporating lessons from EFT-1 and updated requirements for the crewed EM-2 mission.
5) Test like you fly to ensure success: After extensive testing on the ground in “Flight Like” scenarios EFT-1 successfully tested Orion in real flight environments, which could not be duplicated in ground simulations. The systems were subjected to the most critical crew safety requirement with the same rigors they will see when carrying humans. Systems verified included: thermal protection system, hardware separation events and the parachute system. This was a 100% mission success. 87 EFT-1 flight test objectives were identified in the early phases of the test development program. These objectives included verification of Orion’s subsystems ability to launch, control its trajectory with OFI (Operational Flight Instrumentation), complete all separation events, reenter the Earth’s atmosphere at 32, 200 km/hr and 2200ºC, land accurately in the Pacific Ocean and be recovered without damage. 81 of the 87 FTOs (Flight Test Objectives) were fully satisfied with six being partially met. Four of the seven FTO's were related to suspect DFI (Developmental Flight Instrumentation) performance. Two FTO’s related to the Crew Module Up-righting System were partially met, and one FTO related to structural measurements was partially met.
6) Organize for focus: Organizationally, Lockheed Martin and NASA agreed assigning a “mission director” to each test flight would allow program focus on the near term test milestones while maintaining a parallel program focus on the remaining DDT&E (Design, Development, Test, and Evaluation) efforts. EFT-1 was the first mission where this was implemented and proved to ensure the test was completed on time and within budget. This effort also saved over one year of development time for EM-1 by performing this in parallel versus chronologically.
7) Processes and reviews tailored: Since its inception the Orion program has spent significant time focusing on defining an efficient set of requirements to enable the design of Orion as well as optimize the concept of operations for a recurring program rhythm. In an effort to remain flexible the program continues to evolve the requirements based on lessons learned. On EFT-1 the program used a consolidated requirements document approach that was successful in limiting the number of requirements, individual requirements documents, and tiers of requirements documents. The team is using the success of this approach to streamline the EM requirements where possible. Requirements verifications were completed later than planned, partly because the verification work did not carry the same urgency as other launch campaign tasks. The team is looking at a more structured “waterfall” approach to prevent lower level verifications from conflicting with launch campaign activities.
8) Flexibility to accommodate change: Several program planning improvements were accomplished during the course of the program leading up to EFT-1. Improving the Orion IMS ( Integrated Master Schedule) by integrating the NASA “non-Prime” elements improved the continuity of the entire schedule past vehicle delivery. Through Monthly Orion Program Performance Review meetings, the assessments team continued to monitor the contractor performance. Data input for these reviews consisted of Integrated Master Schedule updates, CPRs (Cost Performance Reports), Financial Management Reports (533 inputs), contractor supplemental financial and schedule data, and through participation in the subsystem IPT (Integrated Product Team) meetings. The assessments team integrated these data each month to update the assessment and forecast for the EFT-1 launch date and financial position enabling program management to make rapid decisions.
9) Partnerships ensure Communication: After the President’s proposed cancellation of the Constellation program, NASA and Lockheed Martin recognized reductions needed to occur both on the government side and within Industry to keep the program intact. NASA identified all work within their scope as “Non-Prime” and all work within Industry as “Prime”. NASA and Industry were challenged with a $738.9 M reduction in funding in 2010 and needed to re-plan the entire program in anticipation of this reduction. The cost reduction initiatives they initiated have come to be known as “The streamlining of Orion” and have been used as examples of how NASA and Industry can work together to become more efficient and affordable. The continued emphasis on meeting program objectives within the government’s affordability range have resulted in a refined program plan that accomplishes all of its goals within the annual budget and without jeopardizing mission success. One example of this was the reduction of test flights from seven to four while maintaining the same requirements verifications.
10) Supply Chain must remain healthy: EFT-1 provided the Orion team the ability to exercise 80% of the supply chain that will be utilized for future production vehicles. This includes subcontractors currently spread across 42 states with 60,000 parts being received by NASA or its prime subcontractor in 3 major integration facilities. Throughout this endeavor the processes were validated, enhancements were made and opportunities for improvement identified. EFT-1 helped establish 6 key principles needed to ensure effective supply chain management:
• Centralized supply chain ownership/management offers advantages over IPT ownership
• Need for timely actionable information, including stable engineering design documentation, is mandatory
• Consistent, effective and constant communication is mandatory
• Management of the supplier certification and work load
• Manage with the tools, don’t expect the tools to manage
• Work within the system.
In summary, NASA and Lockheed Martin are taking what we have learned from EFT-1 and years of government investments to make improvements, fly again, making improvements again, and developing a spacecraft that we can proudly stand behind and say we are confident in its abilities to take humans into deep space and bring them safely home.
Some examples of Orion design changes as a result of lessons learned from EFT-1 deals with the structure of the EM.
The Orion design for future Exploration Missions experienced many design optimizations as a result of the EFT-1 flight results. The following section highlights several changes to exemplify optimizations that was realized. Note: (For more information, the reader is referred to Ref. 10).
Structures: Reduced parts and weld assemblies required on the pressure vessel include:
- Reduction from 6 to 3 cone panels, and reduction of cone section welds from 12 to 3.
- Reduction from a 3 piece welded aft bulkhead design to a single spun-formed design.
- Change to an “Apollo-gusset” design in the aft-bay to help reduce the number of separable-parts, and combine structural elements (reduced thruster pod support structures and harness support structures, etc.).
Figure 6: A simplification and reduction of structural parts has been realized by the lessons from EFT-1 (image credit: NASA, Lockheed Martin)
Propulsion: Tubing subassemblies on EFT-1 were custom fit for propulsion system integration (e.g. fit-up tube assembly, cut, face, install heaters / temp sensors, reinstall, repeat as required). On EM-1 no trim to fit will be required on the vehicle. Tubing subassemblies will be delivered in their net shape and subassembly welds will be proof & leak tested prior to delivery.
PCAs (Pressure Control Assemblies) on EFT-1 required a custom fit for propulsion system integration (similar to Tubing subassemblies). On EM-1 there will be improved packaging and attachment methods including PCA welds proof & leak checked prior to delivery.
Propellant and Pressurant Tanks on EFT-1 were difficult to integrate and perform welding operations. The EM-1 design created a new inlet / outlet orientation to ease integration and welding operations.
RCS (Reaction Control System) thrusters on EFT-1 had support struts that have been simplified to a Pod design and attachment method eliminating all struts.
Figure 7: Left: EFT-1 Roll Left Thruster, Right: EM-1 Roll Left Thruster Pods (image credit: NASA, Lockheed Martin)
TPS (Thermal Protection Systems): The Heatshield Avcoat design improvement included changing from a monolithic, individual cell injection process to a “Block Avcoat” design where the heat shield blocks could be automated in production while increasing material properties performance. The use of thermal tape that was used on the EFT-1 heatshield (and similar to Apollo) was changed to use on all backshell and heatshield surfaces for all future Exploration Missions.
Micrometeoroid and Orbital Debris Performance: There are a number of lessons learned in the realm of MMOD (Micrometeoroid and Orbital Debris) environments and analyses, which are being examined and used to influence change for the EM and beyond missions. Chief among these lessons learned is that time spent in the high orbital debris flux altitude band, approximately 650 km to 1200 km, should be minimized. The MMOD analysis performed on EFT-1 was the first such analysis of a human-rated spacecraft above ISS ( International Space Station) altitudes since man-made orbital debris has become an issue, and found the risk at these altitudes (600 km – 1600 km) to be much higher than anticipated; Apollo was too early in spaceflight history for much OD (Orbital Debris) to have accumulated yet. Post-flight inspection of the EFT-1 capsule indicated that actual MMOD exposure may have been even higher than the analyses had assessed. Based on this lesson learned, the parking orbit of EM-1 has been reduced from 3.5 hours in a high-MMOD-risk orbit (2 orbits), to half that time (limited to 1 orbit) to reduce MMOD risk. And as EM-2 trajectory trades and analysis is ongoing, avoiding these altitudes has been accepted as a prerequisite in the EM-2 trajectories. Largely anchored on this finding, other lesson learned recommendations include: increasing MMOD protection in upper-stage and other critical hardware, re-assessing window damage cause and remediation, and continued post-flight inspections and MMOD environment recommended updates based on EM flights.
Radiation Summary: Orion is the first spacecraft that addresses crew radiation protection as an integral part of the vehicle design. We are using a state-of-the-art radiation analysis process to analyze the shielding provided by the vehicle and quantify the internal radiation environment. This analysis is based on the full fidelity Orion CAD model and space radiation environment models. Due to the EFT-1 trajectory passing through the very core of the van Allen proton belts, intravehicular radiation environment was equivalent to 4-6 weeks inside ISS (in terms of cumulative exposure). Thus EFT-1 presented a valuable opportunity to validate our analysis procedure and ultimately improve crew radiation protection for future manned missions. This opportunity was materialized by flying six RAMs (Radiation Area Monitors) on EFT-1. Radiation measurements were in very good agreement with pre-flight predictions, confirming the validity of the radiation analysis approach and providing confidence in our efforts to maintain crew radiation exposure ALARA (As Low as Reasonably Achievable) consistent with NASA requirements.
An important lesson learned for electronic components radiation hardening refers to the importance of considering time variability of the environments in the Single Event Effect rate calculations. The EFT-1 proton environment varied dramatically throughout the mission. Accounting for this time variation was an essential component in selecting the appropriate level of redundancy in critical systems such as the VMC/FCMs (Vehicle Management Computer / Flight Control Modules). This lesson continues to apply to Exploration Missions. Stochastically occurringSPEs ( Solar Particle Events) may cause significant temporary increase in the radiation environment, and critical systems need to design appropriately. A related lesson learned reflects the importance of assessing timing of critical mission events with respect to the radiation environment. Environment assessments performed for EFT-1 drove modification of the mission timeline such that Avionics intensive mission events be executed outside of the core of the van Allen belts. This too is a lesson learned relevant for future missions especially in off-nominal conditions that may expose the spacecraft to high radiation environments.
EM-2 (Exploration Mission-2): EM-2 will be a crewed test flight that will be launched on an SLS and enter lunar orbit in 2022 to verify the capability of Orion to successfully launch, perform a crewed mission, and return them safely to Earth. Figure 2 depicts one option for a lunar mission. The EM-2 configuration will consist of:
• A fully functional launch abort system
• A fully functional Crew Module that includes a crew of up to four and all Cis-Lunar life support systems
• A fully functional Service Module.
Figure 8: EM-2 Design Reference Mission (image credit: NASA)
Figure 9: Technicians with Lockheed Martin, NASA’s prime contractor for Orion, are welding together the pieces of the spacecraft's pressure vessel at Michoud Assembly Center in New Orleans, LA (image credit: NASA)
ESM (European Service Module)
The ESM implements four major system functions to Orion (Ref. 2):
• provides thrust for orbital maneuvers and attitude control after upper stage/launch vehicle separation
• generates electrical power and distributes it to the ESM users and to the CM/CMA
• regulates heat for the life support and avionics equipment during the orbital phases of the mission
• stores and provides to the CMA/CM potable water, oxygen, and nitrogen.
In addition, it ensures structural spacecraft integrity during launch and in-orbit maneuvers. The ESM can also provide additional volume and other resources on select missions for accommodating science, engineering demonstrations, development test objectives, and deployment of lunar infrastructure equipment during the cruise and lunar orbit phases of lunar missions. This volume provides electrical power distribution, network access for command and control interfaces, and structures and mechanisms.
The architecture of the module has been developed based on the ATV spacecraft concept (five successful missions to the ISS),modified to cope with the different mission requirements and the man-rating approach for beyond LEO missions. 11)
Figure 10: Illustration of an ATV cargo freighter in flight with deployed solar arrays (image credit: ESA)
The resulting ESM architecture is depicted in Figure 11, for comparison. The architecture of the system and subsystems hereafter proposed is the reference design for the Lunar Sortie Mission. Changes in the architecture are expected for the other missions to tailor the configuration to mission needs, to remove unnecessary HW and to optimize the launch mass.
European Industrial Consortium: ESA entrusted the development of the ESM (European Service Module) to a consortium of European industries led by Airbus Defence and Space. The consortium of companies was selected to reuse the experience and industrial heritage of the very successful ATV (Automated Transfer Vehicle). Airbus Defence DS Germany as the Prime Contractor is responsible for all system-related work. This includes: 12)
- The overall Management of the contract
- The overall System Engineering activities
- The Management of the procurement activities
- The System Product Assurance and Safety activities
- The liaison with Lockheed-Martin (NASA prime contractor of the Orion vehicle).
Airbus DS, France is responsible for part of the system engineering, ground software, Helium pressurant tanks and simulation facility.
On Subsystem level, Airbus DS, Germany is responsible for the System Engineering, the Propulsion, Power and Avionics Subsystem Engineering as well as for GSE and AIT activities. The responsibility for the development of the other sub-systems or equipment has been distributed among European companies as follows:
TAS (Thales Alenia Space) Italy: the Structure, Thermal and Consumable Storage Subsystems, supported by the following level-2 subcontractors:
- RUAG, Switzerland: secondary structures
- SONACA, Belgium: tank bulkhead
- APCO, Switzerland: MDPS (Meteoroid and Debris Protection System)
- CRISA, Spain, TCU (Thermal Control Unit)
- Prototech, Norway: nitrogen filters
- MEWASA, Switzerland, Water tank bellows.
Dutch Space, The Netherlands: the SAW (Solar Array Wings), supported by the following level-2 subcontractors:
- SELEX SE, Italy for the Photo Voltaic Assemblies
- RUAG, Switzerland: deployment dampers.
Airbus DS, Germany: the propellant tanks, Propulsion Drive Electronic and reaction control thrusters.
RUAG, Switzerland: the SADA (Solar Array Drive Assembly) composed of the mechanism and electronic unit.
SELEX SE, Italy: the PCDU (Power Conditioning and Distribution Unit)
Thales Alenia Space, Belgium: PRU (Pressure Regulation Unit)
Antwerp Space, Belgium: the Electrical Ground Support Equipment Front Ends, supported by the following level-2 subcontractors :
- Clemessy, France
- Rovsing, Denmark.
APCO, Switzerland: Mechanical Ground Support Equipment.
Latelec, France: avionics and power harness
TESAT Germany and Alter, Spain: CPP (Centralized Parts Procurement) scheme for EEE (Electrical, Electronic and Electromechanical)-parts.
Equipment suppliers encompasses Vacco (US), Moog (US), Sofrance (F), Cobham (US), Vivace (US).
Physical architecture: The ESM is a cylindrical unpressurized module which interfaces at its bottom to the SA and at its top to the CMA. The OMS-E (Orbital Maneuvering System -Engine), i.e. the main engine, protrudes into the SA. Equipment on the tank platform is also allowed to protrude into the CMA. The total height of the ESM is 4.0 m.
The cylindrical shape is defined by the external radiators which enclose the body of the ESM. The function of the radiators is twofold, i.e. to radiate heat, and to serve as the first barrier of the MDPS (Micrometeoroid and Debris Protection Subsystem ). Mounted to the back side of the radiators are Nextel and Kevlar blankets which serve as the second barrier. The externally mounted RCS (Reaction Control System) pods and SAWs (Solar Array Wings) must be designed such that these respect the Orion SAJ allowable envelope.
The internal accommodation of the ESM subsystem equipment is highly dependent to the primary structure architecture, based on seven separate bays for accommodation, six located circumferentially about the central bay. The pressurant tanks are accommodated in the center bay. The four largest bays are used for the accommodation of the propellant tanks which dominate the available volume. The remaining volume provides accommodation to the avionics equipment, CSS (Consumable Storage Subsystem) water tanks, harnessing and tubing.
The top surface of the ESM is dominated by the protruding tank domes for the propellant subsystems, one of the helium pressure tanks, the four tanks for Oxygen and Nitrogen, and the Flow Control Assembly for the active cooling subsystem. These elements protrude into the CMA, while maintaining a specific minimum distance to the CM Heat Shield. For these elements above the tank platform, the CMA provides the MDPS protection.
The lower surface is dominated by the OMS-E, which serves as the main engine of the ESM, and the eight auxiliary thrusters. Within the lower platform, a panel is incorporated through which the UPC (Unpressurized Cargo) is installed, and optionally ejected.
Table 3: ESM characteristics for Lunar Missions
Functional architecture: Orion functionalities are generally shared between ESM and CMA/CM. Functional Chains gather equipment of the ESM which participate to a same service provided by Orion for the accomplishment of its mission.
Figure 12 depicts the overall avionics subsystem architecture and interfaces. The interface to the SLS launcher is depicted on the left side of the drawing, and the CM and CMA (labeled as SM-CM I/F Adapter) are on the right side. The main link with Orion CM on-board computers is the ODN (On-board Data Network), based on a time-triggered Ethernet solution. This interface ensures the connection of all ESM avionics to the on-board computers and allows the ESM to receive commands and to deliver monitors.
Few discrete lines ensure the independent command of ESM power subsystem electronics, allow to acquire signals from 8 sun sensors used as back-up AOCS sensors and allow the transfer of data acquired from the development flight instrumentation.
The four SAWs (Solar Array Wings) ensure a maximum electrical power production of 11.2 kW, to cope with a CMA/CM power demand of maximum 7.3 kW to be respected with one wing failed.
Four power buses allow powering to / from the CMA/CM depending on mission phases. Additional and independent power lines are provided for the wireless cameras installed on top of SAWs.
Finally, a dedicated pass-through harness connects the CMA to the SA/SAJ and launcher to allow transfer of monitoring data and separation commands.
The ESM provides translational and 3-axis attitude control for the spacecraft, stores consumables for the crew module and provides power via the solar arrays. The ESM is also being designed to carry cargo. The main subsystems of the ESM are: 13)
• Structure Subsystem
• TCS (Thermal Control Subsystem)
• CSS (Consumable Storage Subsystem)
• PSS (Propulsion Subsystem)
• EPS (Electrical Power Subsystem)
• Avionics Subsystem
Figure 13: Top view of the ESM and its elements (image credit: ESA, Airbus DS)
Figure 14: Illustration of the ESM architecture and principal layout of main elements (image credit: ESA, Airbus DS)
Structure subsystem: The ESM astructure consists of the following major elements:
• Primary structure
• Secondary structure
• MDPS (Meteoroid and Debris Protection).
The primary structure transmits the SLS launch loads to the upper composite composed of the CMA, the CM, and the LAS, then supports the upper composite aerodynamic and inertial loads as well as the ESM inertial loads generated by the ESM internal equipment. The design is based on a shared load path between the ESM and the external SAJ fairings. The objective is to minimize the loads applied on the ESM mechanical structure in order to optimize its mass which is propelled all along the mission, whilst the SAJ capability is sized to the extent possible by the main launch phase, since the SAJ mass is jettisoned early during the launch. The primary structure is composed of:
• 6 longerons (machined aluminum) linked to the CMA frame and six pyronuts that separate the ESM from the Spacecraft Adapter
• Tank bulkhead (machined aluminum) supporting the four propellant tanks, as well as the gas delivery CSS tanks, ensuring the main link between the CMA lower interface ring and the rest of ESM structure.
• "Radial" shear webs and internal "square" webs assembly (composite sandwich panels), housing most of the ESM equipment, including water tanks and SAW support frames and propulsion high pressure system. It forms the ESM core attached to the tank bulkhead, longerons and lower closeout panels. The main engine is attached to the central square tube panels via struts transmitting the thrust.
• Lower Platform (machined aluminum) on which the equipment is connected: OMS-E main engine, auxiliary thrusters supports, RCS pods supports, SAD (Solar Array Drive) mechanism, and PIE (Propulsion Isolation Equipment).
• MDPS covers and aft closure panels to protect the ESM from the MMOD (Micrometeoroid and Orbital Debris) environment.
The secondary structures support the ESM equipment carrying the inertial and dynamic loads of the equipment during launch and transmitting in-orbit thrust and inertial loads.
The MDPS is partly metallic and partly composed of Nextel reinforced MLI (Multi-Layered Insulation). Debris and meteoroid particles with velocities up to 24 km/s hit the outer wall, forming a cloud of lower energy particles which are then contained by the inner wall, preventing any penetration of the ESM.
Figure 15: Primary and secondary structures (image credit: ESA, Airbus DS)
TCS (Thermal Control Subsystem): The TCS includes an ATCS (Active Thermal Control Subystem), a PTCS (Passive thermal control Subsystem) and the TCU (Thermal Control Unit).
11) ATCS (Active Thermal Control Subystem): The ATCS is designed to collect the thermal loads from the CM and from the ESM powered equipment and to reject them toward the space radiative sink. The ATCS architecture is based on a Single-phase Fluid Loop Architecture using the HFE-7200 coolant to collect and to transfer the heat loads from both ESM avionics (via cold plates) and CM (via Inter-Loop Heat Exchanger) and to reject them through specific body mounted radiators. The ATCS is composed of two fully independent loops working simultaneously (hot redundancy approach). The schematic of the ATCS architecture is presented in Figure 16.
Each ATCS loop is composed by the following main components:
• 1 Radiator Assembly commonly used for both loops and composed of 4 full height radiators and 2 split radiators (with lower part not removable) mounted in serial configuration
• 1 CP (Cold Plate)
• 2 online APSBs (Absolute Pressure Sensor Blocks)
• 1 wet on-line TSB (Temperature Sensor Block)
• 1 FCA (Fluid Control Assembly) including redundant pumps with relevant passive accumulator and a TWMV (Three-Ways Modulating Valve)
• Hard/flex hoses, tees, couplings and restrictors.
The FCA is controlled by the TCU to provide constant mass flow rate inside the loop. In particular two flow rate set points are foreseen, one for nominal operation and one for contingency (with only one loop operative). The FCA also includes the TWMV, controlling the temperature at the ESM-CMA interface.
The external surface of the radiator panels is coated with a specific paint characterized by the following thermal-optical characteristics:
• Alpha (α) = 0.2
• Emissivity (ε) = 0.8.
The Cold Plates are devoted to collect the entire thermal load from the ESM avionics boxes. Their design is constituted by a stainless steel channelling enclosed in an aluminum casting acting as a plate in direct contact with the thermally active unit. Different Cold plate sizes, to satisfy the different configuration needs, are foreseen.
Figure 17: Photo of a sample radiator panel (image credit: ESA, TAS)
12) PTCS (Passive Thermal Control Subsystem): The PTCS provides the thermal control of ESM hardware (propulsion, CSS, power and avionic items) and reduces the temperature gradients and minimize heat flows through the internal elements. The PTCS has two main components, heaters (with thermistors and wire heater) and insulation (MLI thermal blankets, including some specific high temperature MLI blankets, for thrusters and engine nozzle thermal impingement protection).
The MLI protects the internal parts against the external environment and heater lines compensate the heat leaks toward space. Different MLI typologies, in terms of composition, have been identified for the different applications on the ESM. The MLI composition mainly depends on exposure or not to the space, geometry & fixation interfaces and exposure to thrusters plume flux and nozzle radiation.
Two cold redundant heater lines managed by the TCU assure thermal control and temperature uniformity in the Orion internals and for the local thermal control of specific items. In addition, heater lines managed by thermostats and powered by the PCDU (Power Control and Distribution Unit) provide a further redundancy to the environmental control function.
13) TCU (Thermal Control Unit): The TCU is designed to ensure the management of the TCS and of the CSS.
For the ATCS, the TCU acquires the various parameters from the ATCS sensors, monitors and commands the ATCS valves, and issues commands to the FCA (Flow Control Assembly).
For the PTCS, the TCU commands the heater chains and monitors the thermistors. It operates according to activation and de-activation thresholds defined and modified by the CM on-board computers, while ensuring bus interface and power supply logic.
For the CSS (Consumables Storage Subsystem), the TCU commands the valves and monitors their position. It also monitors the pressure and temperature parameters in the subsystem to support the system FDIR (Failure Detection, Isolation and Recovery).
Figure 18: Layout of the TCS (Thermal Control Subsystem), image credit: ESA, Airbus DS
CSS (Consumable Storage Subsystem): The CSS provides potable water, oxygen and nitrogen to the CM. It can also provide water for the sublimator located in the CMA via a dedicated kit composed by its own tank assy and distribution system, to be installed optionally for specific missions. It consists of the following major elements:
• WDS (Water Delivery Subystem)
• GDS (Gas Delivery Subsystem)
The architecture of the WDS is composed of the following components:
• Water tanks (metal bellow technology)
• Water on/off valves, (isolation valves)
• Temperature and quantity sensors
• 2 distribution lines towards the CMA I/F to supply water for the different CM/CMA needs.
The architecture of the GDS is composed of the following components:
• Gas tanks
• Gas pressure regulators
• Gas on/off valves, (isolation valves)
• Gas relief valves
• Temperature and pressure sensors
• Hydrophobic filters upstream the water tanks
• Distribution lines towards the CMA I/F to supply oxygen and nitrogen
• Distribution lines towards CMA I/F for GDS filling on ground from the GSE.
In the case of a configuration with WSK (Water Sublimator Kit) a set of 3 additional water tanks is introduced and interconnected to the others tanks and lines of CSS.
Figure 19: Layout of the CSS (image credit: ESA, Airbus DS)
PSS (Propulsion Subsystem): The propulsion subsystem design has to cope with a complex mission scenario. It includes three different types of engines / thrusters. Each of these thrusters utilizes the same propellants: MON-3 (Mixed Oxides of Nitrogen) as oxidizer and MMH (Monomethylhydrazine) as fuel.
The single Main Engine, which is one of the Shuttle OMS-E engines (27.7 kN), is delivered by NASA as GFE (Government Furnished Equipment) and will be used during ascent abort and trans-earth injection maneuvers as well as orbit change maneuvers. This engine is gimballed with an amplitude of ± 7° around both axes (pitch and yaw). The actuation is performed by the TVC (Thrust Vector Control).
The 8 auxiliary thrusters which are similar to those used on ATV (490 N) are used during ascent abort and launcher separation together with the main engine. They are also used as backup to the main engine for trans-earth injection and for trajectory correction maneuvers.
The 24 RCS thrusters which are the same as used on ATV (220 N) provide the impulse necessary for attitude control, small maneuvers and forced translation during Rendezvous and Proximity operation. These thrusters are accommodated into six pods. Two pods are composed of four roll thrusters, placed along the ESM lateral surface under the CMA, while four other pods are composed of four thrusters, placed along the ESM lateral surface under the level of the first four pods. Each propellant type is stored in two propellant tanks, both sets of propellant tanks being arranged in a series configuration.
The propellant distribution comprises several electromechanical valves for propellant isolation and pressure transducers interconnected via pipes. The assembly ensures isolation of the engine / thrusters from the propellant tanks during launch, docked phase to the ISS and other mission events where it becomes necessary to isolate the engine / thrusters from the propellant storage. The propellant distribution network provides the connections between the propellant tanks and the isolation valves and then onwards to the thruster assemblies. Fill and Drain Valves and the related access lines are used during ground testing and for loading and unloading of the propellant and pressurized tanks. They are located in the CMA to enable access even after the SAJ around the service module has been installed.
The propulsion subsystem is controlled by the PDE (Propulsion Drive Electronics) which handles all nominal propulsion related commands issued by the CM and provides feedback via the CMA PDUs (Power Distribution Units) and the PDUs to the vehicle management computer interface and the ESM network. The PDE controls all thrusters, the TVC and the associated valves, instrumentation and leakage detection.
The PRU (Pressure Regulation Unit) controls and monitors the operation of the pressure regulation valves, based on set points defined and modified by the on-board computers. The EPR (Electronic Pressure Regulation) selected for ESM has the advantage to optimize the pressure of propellant and oxidizer according to the engine in operation, at the price of an increased development risk for this function.
The EPR of the propulsion system propellant is a new technology for the European industry. The ATV design featured a mechanical pressure regulation like the propulsion system of the Shuttle OMS-E engine. The electronic pressure regulation allows a better control of the pressure, hence the fuel and oxidizer consumption is enabling to reduce propellant margins and the overall mass at launch. Airbus DS decided to venture in that new technology as a result of a trade-off taking into account the positive results obtained by Lockheed-Martin in breadboard testing. However, in the development of a new technology there is always the risk of not being successful especially if the development time is constrained.
To mitigate the impact to the project in case of unsuccessful development, it was decided to ensure that reverting to mechanical pressure regulation would be possible with minimum schedule impact. NASA provided Shuttle mechanical pressure regulators and valves to VACCO, the original manufacturer and Airbus DS ordered tests to ensure the hardware would satisfy the performance required for the ESM. Breadboard testing of the electronic regulation performed in Europe up to now delivered promising results and the probability of having to revert to mechanical pressure regulation is becoming more remote.
Figure 20: Layout of the propulsion subsystem (image credit: ESA, Airbus DS)
EPS (Electrical Propulsion Subsystem): The EPS has the function to generate the power for all modules of Orion. It manages the power provided by its 4 SAW (Solar Array Wings). The PCDU (Power Control and Distribution Unit) provides the power I/F to the SAW and CMA, distributes electrical power to ESM users and protects the power lines.
The power generation part of the ESM EPS consists of four SAW units. Each wing is composed of three deployable CFRP (Carbon Fiber Reinforced Polymer) rigid panels covered with triple junction GaAs solar cells forming nine (9x) sections of solar cell strings. In nominal condition the SAW can supply a total 11.2 kW. Each SAW is linked to the ESM structure by a two degree of freedom SADA (Solar Array Drive Assembly). The SADA ensures the power and signal transfer from the SAW to the PCDU. It is composed of SADM (Solar Array Drive Mechanism) and a (SADE (Solar Array Drive). The SADM allows orienting the SAW in two independent axes. In the Sun-tracking mode the inner axis can swivel between -35º and +25º, while the outer axis has a continuous rotation capability (0º; +360º).
SADM of the ESM has a unique design incorporating a two axis gimbal. An inner axis provides rotation of the SAW about an axis perpendicular to the ESM longitudinal axis, and an outer axis which rotates the SAW about its own longitudinal axis. The two-axis capability is necessary for two reasons:
1) allow maximum sun tracking to meet the power requirements for particular vehicle attitudes of certain mission phases. Insufficient power is generated by the SAW with a single (roll) axis SADM not providing the avoidance capability of the shadowing effect of both the Orion vehicle on the SAW and the SAWs on each other
2) insure the structural integrity of the SAWs under injection maneuvers. For the trans-lunar injection performed with the upper stage of the Space Launch System rocket, actually the iCPS (interim Cryogenic Propulsion Stage), the arrays are canted backwards to sustain in deployed configuration the 1 g acceleration load. For the trans-earth injection performed with the ESM main engine, the acceleration is less severe and the arrays have to be canted forwards to prevent damages from the OMS-E engine plume while minimizing the load on the SAWs.
The SADM also allows repositioning (canting) of the SAW to reduce the loads on the SAW and SADM during the different Orion orbital maneuvers. At TLI (Trans-Lunar Injection), a 0.5 g acceleration is generated by the iCPS engine and at LOI (Lunar Orbit Insertion) and TEI (Trans-Earth Injection) a 0.3 g deceleration is generated by the OMS-E engine.
As shown in Figure 21, in order to reduce these loads to an acceptable level, the SAWs need to be repositioned by the SADM. In TLI, the SAWs are thus canted during the maneuver to inner axis = - 60º / outer axis = 0 º. In LOI/TEI, the SAWs are canted to inner axis = +55º / outer axis = 0º.
The EPS distributes the generated power to the CMA/CM through four independent 120 V busses. The power interfaces of the PCDU protect each unregulated bus from overload or short circuit failures on feeder busses outside the PCDU. They are implemented with power devices connected in parallel and independently operated for power flow from PCDU to CMA PDU, plus a number of power diodes for power flow from CMA PDU to PCDU.
Avionics Subsystem: The high-level management of the vehicle and its functions is performed at the level of the Orion on-board computers. The ESM is controlled and monitored by specific electronic controller units. All units are connected via the ODN (Onboard Data Network) to the CMA/CM. All vehicle control and management software resides in the CM computers. The ODN is a three plane TTGbE (Time Triggered Gigabit Ethernet),1000Base-CX, according to standard SAE AS6802.
The Time-Triggered Gigabit Ethernet ODN provides a set of time-triggered services implemented on top of standard IEEE802.3 Ethernet. It provides the capability for deterministic, synchronous, and congestion-free communication, unaffected by any asynchronous Ethernet traffic load. By implementing this standard in network devices (network switches and network interface cards), Ethernet becomes a deterministic network. This means that distributed applications with mixed time-criticality requirements (e.g., real-time command and control, audio, video, voice, data) can be integrated and coexist on one Ethernet network.
Each of the ESM controller units is connected via a SNIC (Standard integrity Network-Interface Card), according to Honeywell ICD8273722, to the LAN switch located in the CMA. The SNICs have three ports for two failure-tolerant communication on three network redundancy planes.
Development: The challenging schedule of the program, with the ESM delivery planned for early 2017 and the EM-1 launch planned for 2018, is influencing the way the ESM is verified. Qualification has often to run in parallel to EM-1 flight model manufacturing and integration, bringing risk to the program. This risk is carefully monitored and risk reduction strategies are in place to ensure the program can proceed smoothly. The ESM verification is mostly accomplished at module level. A limited number of verifications is planned on the EM-1 flight model.
- The system PDR (Preliminary Design Review) was successfully concluded in the summer 2014.
- The system CDR (Critical Design Review) is scheduled for the end of2015 and will conclude with the board in February 2016.
Table 4: Summary of key aspects for an international partnership in the Orion program
Development status of Artemis-1, formerly Orion EM-1 (Exploration Module-1) and ESM (European Service Module)
• July 30, 2020: The second to last piece of hardware for the Artemis-1 test flight around the Moon has arrived at the agency’s Kennedy Space Center in Florida. The launch vehicle stage adapter (LVSA) connects the core stage of NASA’s Space Launch System (SLS) rocket to the upper stage, called the Interim Cryogenic Propulsion Stage. The cone-shaped connector also helps protect the RL10 engine housed in the upper stage, which will provide the power necessary to leave Earth’s orbit and send the Orion spacecraft on its journey to the Moon. 14)
Figure 22: NASA's Pegasus barge, carrying the launch vehicle stage adapter (LVSA) for the agency's Space Launch System (SLS) rocket, arrives at the Kennedy Space Center Launch Complex 39 turn basin wharf on July 29, 2020. Traveling to Florida from NASA's Marshall Space Flight Center in Huntsville, Alabama, the LVSA will connect the SLS core stage to the rocket's upper stage for the Artemis I launch (image credit: NASA/Isaac Watson)
- “The launch vehicle stage adapter arriving to Kennedy is significant because we have almost all of the pieces of the rocket here as we get closer to launch,” said Allison Mjoen, operations project engineer with the Exploration Ground Systems program. “We have moved from planning into implementation, and soon the rocket will begin taking shape with stacking operations.”
- Arriving at Kennedy’s Launch Complex 39 turn basin wharf, the LVSA traveled from NASA’s Marshall Space Flight Center in Huntsville, Alabama, to Florida on the agency’s Pegasus barge – a 310-foot-long vessel that has been modified to transport the largest rocket stage in the world: the SLS core stage. Technicians offloaded the LVSA and transported it to the Vehicle Assembly Building, where it will be stored until it is needed for stacking on the rocket. The core stage – made up of the forward skirt, liquid oxygen tank, liquid hydrogen tank, and the engine section containing the rocket’s four RS-25 engines – is the final piece of the rocket that will be delivered to Kennedy ahead of the Artemis I launch.
Figure 23: Technicians with NASA’s Exploration Ground Systems move the launch vehicle stage adapter (LVSA) for the agency’s Space Launch System (SLS) rocket to the Vehicle Assembly Building (VAB) on July 30, 2020, for processing. The LVSA will connect the SLS core stage to the rocket’s upper stage and will remain in the VAB until it’s time for stacking on the mobile launcher ahead of the Artemis I launch. The first in a series of increasingly complex missions, Artemis I will test SLS and the Orion spacecraft as an integrated system prior to crewed flights to the Moon (image credits: Jacobs/Tracy Yates)
- Under the Artemis program, NASA is working toward landing the first woman and the next man on the Moon by 2024. Artemis I will test SLS and Orion as an integrated system prior to crewed flights and is the first in a series of increasingly complex missions that will enable human exploration to the Moon and Mars. SLS and Orion, coupled with the Human Landing System and the Gateway in orbit around the Moon, will be the agency’s backbone of deep space exploration.
• June 16, 2020: The rocket booster segments that will help power NASA’s first Artemis flight test mission around the Moon arrived at the agency’s Kennedy Space Center in Florida on Monday for launch preparations. 15)
- All 10 segments for the inaugural flight of NASA’s first Space Launch System (SLS) rocket and Orion spacecraft were shipped by train from Promontory, Utah. The 10-day, cross-country journey is an important milestone toward the first launch for NASA’s Artemis program.
Figure 24: Twin rocket boosters for NASA’s Space Launch System (SLS) that will power Artemis missions to the Moon have arrived at the agency’s Kennedy Space Center in Florida. The two motor segments, each comprised of five segments, arrived at Kennedy’s Rotation, Processing and Surge Facility (RPSF) on June 15, 2020, by train from a Northrop Grumman manufacturing facility in Promontory, Utah. The booster segments will remain in the RPSF for inspection prior to processing until it’s time to move them to the Vehicle Assembly Building for stacking on the mobile launcher. This is the first piece of flight hardware to arrive at Kennedy by train for the Artemis program, but NASA’s Exploration Ground Systems (EGS) can expect to receive additional hardware soon, including the Launch Vehicle Service Adapter and the rocket’s core stage. NASA is working toward an Artemis I launch date in 2021, keeping the program moving at the best possible pace toward the earliest possible opportunity (image credit: NASA/Kevin O'Connell)
- “The arrival of the booster segments at Kennedy is just the beginning of the SLS rocket’s journey to the pad and onward to send the Orion spacecraft to the Moon,“ said NASA Administrator Jim Bridenstine. “Artemis I will pave the way toward landing the first woman and the next man on the surface of the Moon in 2024 and expanding human exploration to Mars.”
- Each rocket booster has individual motor segments, located between the forward assemblies and aft skirts, making up the largest single component of the entire booster. The two SLS rocket boosters, four RS-25 engines, and core stage, produce a combined total of more than 8.8 million pounds of thrust power during launch.
- “It’s an exciting time at NASA’s Kennedy Space Center as we welcome Artemis flight hardware and continue working toward the Artemis I launch,” said Kennedy Space Center Director Bob Cabana.
- Each booster segment, weighing 180 tons, is filled with propellant and outfitted with key flight instrumentation. Due to their weight, Northrop Grumman, which is the booster lead contractor, transported the segments in specially outfitted railcars to make the 2,800-mile trip across eight states to Florida’s Space Coast.
- “The fully assembled boosters for NASA’s Space Launch System rocket are the largest, most powerful solid propellant boosters ever built for flight,” said Bruce Tiller, manager of the SLS Boosters Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “These enormous rocket motors help provide the necessary launch power for the SLS deep space rocket.”
- Now that the booster segments are at Kennedy, NASA’s Exploration Ground Systems team will prepare them for assembly and integration activities that start with offloading the segments. Teams will attach the aft segments to the aft skirts and offload and store the remaining segments from the railcars in preparation for stacking.
- “It is good to see booster segments rolling into the Kennedy Space Center,” said Mike Bolger, program manager of Exploration Ground Systems. “The team can’t wait to get started working on the boosters that will send the SLS rocket and Orion spacecraft on the first Artemis mission to the Moon.”
- The solid rocket boosters are the first elements of the SLS rocket to be installed on the mobile launcher in preparation for launch. The aft booster assemblies will be lifted on to the mobile launcher, followed by the remaining booster segments, and then topped with the forward assembly.
- Teams at Kennedy have been preparing for the arrival of the booster segments by assembling and testing the aft skirts and forward assemblies of the boosters, and practicing stacking procedures with booster pathfinders, or hardware replicas, earlier this year. NASA and Northrop Grumman completed casting in 2019 of all 10 of the motor segments for both the first and second Artemis lunar missions, and are now working on the boosters for the Artemis III mission, which will land the first woman and next man on the Moon in 2024.
- With the arrival of the boosters, the only remaining pieces of hardware for the Artemis I flight test to be delivered to Kennedy are the launch vehicle stage adapter, which connects the rocket to the Orion spacecraft and will arrive this summer, and the SLS core stage, which will be transported to Kennedy by barge after the Green Run hot fire test later this year at NASA’s Stennis Space Center near Bay St. Louis, Mississippi.
- Through the Artemis program, NASA will return astronauts to the Moon’s surface in four years. SLS, along with NASA’s Orion spacecraft, the Human Landing System and the Gateway in orbit around the Moon, will serve as NASA’s backbone for deep space exploration. SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon on a single mission. We’ll explore more of the lunar surface than ever before, and collaborate with our commercial and international partners to establish sustainable exploration by the end of the decade. Then, we will use what we learn on and around the Moon to take the next giant leap – sending astronauts to Mars.
Figure 25: A train carrying the rocket motors for NASA’s Space Launch System rocket after departing a Northrop Grumman manufacturing facility in Utah for NASA’s Kennedy Space Center in Florida on June 5, 2020. The 10 booster segments will power Artemis I, the first mission of NASA’s Artemis program, to the Moon. The 180-ton booster segments are transported in specially outfitted railcars to make the 2,800-mile trip across eight states to Kennedy (image credit: Northrop Grumman)
• April 23, 2020: Before NASA’s mighty Space Launch System (SLS) rocket can blast off from the agency’s Kennedy Space Center to send the Orion spacecraft into lunar orbit, teams across the country conduct extensive testing on all parts of the system. Guiding that effort at the Florida spaceport are NASA Test Directors (NTDs).
Figure 26: NASA Launch Director Charlie Blackwell-Thompson, above, confers with Senior NASA Test Director Jeff Spaulding, left, and Test, Launch and Recovery Operations Branch Chief Jeremy Graeber in Firing Room 1 at Kennedy Space Center's Launch Control Center during a countdown simulation (image credit: NASA/Cory Huston)
- NTDs within the Exploration Ground Systems program are in charge of flight and ground hardware testing in Kennedy’s Launch Control Center firing rooms 1 and 2, where activities involved with preparing rockets, spacecraft and payloads for space can be controlled from computer terminals. They are responsible for emergency management actions, helping lead the launch team during all facets of testing, launch and recovery.
- NASA’s Artemis missions will land American astronauts on the Moon by 2024, beginning with Artemis-1, the uncrewed flight test of SLS and Orion.
- “It’s certainly an amazing feeling to be responsible for setting up the building blocks of a new program which will eventually take us to the Moon, Mars and beyond,” said Senior NASA Test Director Danny Zeno.
- Zeno is leading the development of test plans and procedures that are essential to flight and ground hardware for the Artemis missions. This includes proving the functionality of flight and ground systems for the assembled launch vehicle configuration, verifying the mobile launcher arms and umbilicals operate as expected at launch, and performing a simulated launch countdown with the integrated vehicle in the Vehicle Assembly Building.
- The 14-year NTD veteran relishes his hands-on role in successfully testing and launching SLS — the most powerful rocket NASA has ever built.
- “It’s very fulfilling,” Zeno said. “What excites me about the future is that the work I’m doing today is contributing to someday having humans living and working on other planets.”
- There are 18 people in the NTD office — all of whom must undergo rigorous certification training in the management and leadership of test operations, systems engineering and emergency response. They are in charge of the people, hardware and schedule during active firing room testing.
- “The NTD office is at the center of testing operations, which will ensure that we are ready to fly the Artemis missions,” said Launch Director Charlie Blackwell-Thompson. “As we lay the foundation for exploring our solar system, the NASA test directors are on the front lines of making it happen.”
- An NTD works from a console in the firing room during integrated or hazardous testing, guiding the team through any contingency or emergency operations. They lead critical testing on Launch Pad 39B and the, the 370-foot-tall, 11 million-pound steel structure that will launch the SLS rocket and Orion spacecraft on Artemis missions to the Moon and on to Mars. This includes sound suppression, fire suppression and cryogenic fluid flow tests, as well as testing the crew access arm and umbilicals — connections that will provide communications, coolant and fuel up until launch.
- While the majority of work for the ground and flight systems is pre-liftoff, the job certainly doesn’t end there.
- “It culminates in a two-day launch countdown in which all of the groups, teams and assets are required to function together in an almost flawless performance to get us to launch,” said Senior NASA Test Director Jeff Spaulding.
- Spaulding has nearly three decades of experience in the Test, Launch and Recovery Office. For Artemis-1, he is leading the launch control team and support teams during the launch countdown for Blackwell-Thompson, who will oversee the countdown and liftoff of SLS.
- Just over three miles from the launch pad, on launch day, Spaulding will be in the firing room running the final portion of cryogenic loading through launch. During this time, supercool propellants — called cryogenics — are loaded into the vehicle's tanks. He will perform the same tasks for the wet dress rehearsal, which is a full practice countdown about two months before launch that includes fueling the tanks and replicating everything done for launch prior to main engine start.
- At the end of the mission, part of the team will lead the recovery efforts aboard a Navy vessel after Orion splashdown. The NASA recovery director and supporting NTDs are responsible for planning and carrying out all operations to recover the Orion capsule onto a U.S. Navy ship. This includes working closely with the Department of Defense to ensure that teams coordinate recovery plans, meet requirements, and follow timelines and procedures to bring our heroes and spacecraft home quickly and safely.
- “We are supported by numerous teams at Kennedy and elsewhere around the country that are helping us with our historic first flight as we blaze a path toward landing astronauts on the Moon in 2024,” Spaulding said.
• March 27, 2020: The Orion spacecraft that will fly on the Artemis-1 mission around the Moon has returned to NASA’s Kennedy Space Center in Florida, USA, after finishing space environment tests. The spacecraft, including ESA’s European Service Module, is now at its final destination before launch. 16) 17)
- Orion spent four months at NASA’s Plum Brook station where it was subjected to the vacuum and temperatures of –175°C to 75°C it will experience on its flight to the Moon. After proving its space-worthiness, the electronics - including the thousands of parameters and functions of the European Service Module that control the engines, electrical power and steering the solar panels to face the Sun - were checked for electromagnetic interference.
- ESA’s Dominique Siruguet from the European Service Module integration and verification team says “The tests were successful and the behavior of the vehicle was good, passing all requirements.”
- Plum Brook station was chosen for the tests because thermal vacuum and electromagnetic compatibility could be performed in the same facility. This avoided additional transport of Orion, which is the size of a two-story house.
- Having passed its trials, the spacecraft was wrapped and moved by truck to an airport in Ohio for its return flight on NASA’s Super Guppy aircraft.
Figure 27: Super Guppy leaves Ohio with the Artemis-1 Orion spacecraft (image credit: NASA, Nicole Smith)
Adding wings to Orion
- The tests are not completely over for Orion, at Kennedy Space Center the crew module will be further prepared and more leak tests conducted. The European Service Module has tanks for fuel, oxygen and water that are critical for the astronauts. The gas tanks are pressurized and are connected to many pipes and valves, so it vital to make sure there are no leaks.
- The solar wings that generate power during its mission will be installed, as well as protective covers called the Spacecraft Adapter Jettisoned fairings for the intense moments of launch on the world’s most powerful rocket.
- Later this year ESA will formally transfer ownership of the European Service Module to NASA and the spacecraft will move into the ground system phase where it will be united with the SLS rocket for a lift-off to the Moon.
- Orion is a key component of Artemis-1 — an uncrewed test flight around the Moon that paves the way for the Artemis-3 mission, which will land the first woman and next man on the lunar surface by 2024. ESA is designing and supplying the European Service Module for the Orion spacecraft. This provides electricity, water, oxygen and nitrogen. It also keeps the spacecraft at the right temperature and on course, propelling it to the Moon and back once it has separated from the launcher.
Figure 28: Orion service module – from components to shipping. A look at the elements that make up the European service module that will provide power, water, air and electricity to NASA’s Orion Moon module (video credit: ESA)
• March 20, 2020: The following is a statement from NASA Administrator Jim Bridenstine: “NASA leadership is determined to make the health and safety of its workforce its top priority as we navigate the coronavirus (COVID-19) situation. To that end, the agency’s Michoud Assembly Facility and Stennis Space Center are moving to Stage 4 of the NASA Response Framework, effective Friday, March 20. 18)
- “The change at Stennis was made due to the rising number of COVID-19 cases in the community around the center, the number of self-isolation cases within our workforce there, and one confirmed case among our Stennis team. While there are no confirmed cases at Michoud, the facility is moving to Stage 4 due to the rising number of COVID-19 cases in the local area, in accordance with local and federal guidelines.
- “Mandatory telework is in effect for NASA personnel at both facilities until further notice. Additionally, all travel is suspended. These measures are being taken to help slow the transmission of COVID-19 and protect our communities.
- “Access to Stennis and Michoud will be limited to personnel required to maintain the safety and security of the center, as approved by agency leadership and the resident agencies. All previously approved exceptions for onsite work are rescinded and new approvals will be required in order to gain access to the center.
- “NASA will temporarily suspend production and testing of Space Launch System and Orion hardware. The NASA and contractors teams will complete an orderly shutdown that puts all hardware in a safe condition until work can resume. Once this is complete, personnel allowed onsite will be limited to those needed to protect life and critical infrastructure.
- “We realize there will be impacts to NASA missions, but as our teams work to analyze the full picture and reduce risks we understand that our top priority is the health and safety of the NASA workforce.
- “I ask all members of the NASA workforce to stay in close contact with your supervisor and check the NASA People website regularly for updates. Also, in these difficult times, do not hesitate to reach out to the NASA Employee Assistance Program, if needed.
- “I will continue to say, so none of us forget – there is no team better prepared for doing hard things. Take care of yourself, your family, and your NASA team.”
• March 16, 2020: The first Orion spacecraft that will fly around the Moon as part of Artemis to return humans to the lunar surface has finished its space-environment tests at NASA’s Plum Brook Station in Ohio, USA. The vehicle – that can transport up to four astronauts – consists of the European Service Module, the Crew Module and connecting adapter and all elements have now been given the stamp of approval for spaceflight after being subjected to the vacuum, extreme temperatures and electromagnetic interference it will encounter during its trip to the Moon. 19)
- Orion arrived at Plum Brook Station – the only center large enough to test the spacecraft – on 26 November and passed two months of thermal-vacuum tests subjecting the spacecraft to temperatures ranging from –175°C to 75°C in vacuum.
- After passing the trial by temperature, Orion went through electromagnetic interference testing to ensure the electronics worked well together – the European Service Module has over 11 km over wiring to gather information and send commands to its 31 engines, propellant tanks, solar wings and more.
- Orion will now ship to NASA’s Kennedy Space Center where it will be further prepared for launch, including assembling the solar panels and more individual tests.
Figure 29: Orion is a key component of Artemis-1, an uncrewed test flight around the Moon that paves the way for the Artemis-3 mission which will land the first woman and next man on the lunar surface by 2024. ESA is designing and supplying the European Service Module for Orion – the bottom part of the spacecraft in the picture – that provides electricity, water, oxygen and nitrogen as well as keeping the spacecraft at the right temperature and on course (image credit: NASA–Marvin Smith)
• March 3, 2020: Radio frequency testing has begun on the first Orion spacecraft that will fly around the Moon for the Artemis-1 mission, just two weeks after thermal and environmental tests were completed at NASA’s Plum Brook Station in Ohio, USA. 20)
- EMC (Electromagnetic Compatibility) testing is routine for spacecraft. All electronics emit some form of electromagnetic waves that can cause interference with other devices. Think of the buzz that speakers give out right before an incoming call on a mobile phone.
- Spacecraft electronics can cause similar interference, but out in space such interference can have disastrous consequences, so all systems must be checked before launch.
- EMC tests often take place in a special shielded room constructed of metal walls and doors and foamy spikes (aka Absorbers) that block out unwanted external electromagnetic radiation, like ESA’s Maxwell chamber at its technical site in the Netherlands.
- Though not an EMC chamber, Plum Brook’s thermal vacuum chamber is made of aluminum that does provide electromagnetic shielding, making it a suitable substitute.
- To test electronics, the spacecraft will simulate a flight in realistic conditions with most of its subsystems and equipment powered and in operational mode.
- The electronics are first tested for compatibility in this electromagnetic shielded chamber. Equipment will be switched on to test whether they do potentially disturb one another.
- In the second round of tests, electromagnetic fields will be applied using antennas around the spacecraft to test the susceptibility to interference from external sources. The Orion capsule is equipped with electromagnetic field sensors to take measurements as the disturbance frequencies are injected into the chamber.
- While all subsystems are a potential source of radio frequency noise, of particular interest are the transmitters that intentionally generate radio frequencies. These can easily disturb other equipment sensitive to electromagnetic noise, like GPS receivers, telecommand modules and other communication elements.
- Orion’s European Service Module provides power, propulsion, and crew life support.
- ESA experts are on site monitoring all tests alongside NASA colleagues as Orion moves closer to its first flight without a crew around the Moon.
• January 14, 2020: The first flight of the Artemis program, Artemis-1, is scheduled to begin soon. The lunar spacecraft consists of NASA's Orion crew module and the ESM (European Service Module). Developed by ESA and building on technology from its ATV (Automated Transfer Vehicle), the ESM will provide propulsion, life support, environmental control and electrical power to Orion. The Artemis-1 spacecraft modules are undergoing thermal vacuum and electromagnetic interference tests in the world's largest space simulation vacuum chamber at the Glenn Research Center's Plum Brook Station in Sandusky, Ohio, USA. 21)
Figure 30: Back to the Moon with ESA (video credit: ESA)
• January 13, 2020: NASA’s Kennedy Space Center in Florida will have a busy year preparing facilities, ground support equipment and space hardware for the launch of Artemis-1, the first uncrewed launch of the Space Launch System (SLS) rocket and the Orion spacecraft. In 2020, Exploration Ground Systems (EGS) activities will ramp up as launch hardware arrives and teams put systems in place for Artemis-1 and -2 missions. 22)
Launch Countdown Simulation Activities
Launch countdown simulations will continue to ramp up in 2020 to train and certify the launch control team for Artemis missions. The types of simulations will build on one another and will walk through the final portions of the launch countdown sequence, called the terminal countdown. Integrated simulations will tie in all NASA centers working the mission to ensure all members of the team are ready to work together, including Mission Control at Johnson Space Center in Houston, and the SLS Engineering Support Center at Marshall Space Flight Center in Alabama. Simulations will begin at the end of January and will occur up through one week before launch, with an average of one training exercise each month.
Vehicle Assembly Building
Much of the work in 2020 will be to complete a punch list of detail work inside the VAB (Vehicle Assembly Building). This includes cleaning the platforms and making minor repairs to any platform hardware that will be near flight hardware as the facility prepares for arrival of SLS components and stacking operations.
“We are at a very significant point in NASA’s Artemis mission,” said Mike Bolger, program manager of EGS. “The EGS team has finished mobile launcher testing at the launch pad and will finish testing at the VAB in January. At that point, all of the launch infrastructure will be tested and ready for operations.”
Launch Complex 39B
Teams will continue work on a new emergency egress system for Pad 39B where flight or ground crew could board a basket with a braking system at the crew access level of the mobile launcher. The crew would ride the basket down a cable and come to a stop near a bunker to the west of the pad surface, providing quick escape in the unlikely event of an emergency. The design phase began in 2019 and construction will be complete in time to support crewed Artemis missions.
The pad is currently getting a liquid hydrogen upgrade. The project involves the integration of a new 1.4 million gallon, liquid hydrogen (LH2) storage sphere into the existing Launch Complex 39B system. The new LH2 sphere will work with the current LH2 sphere to supply LH2 for Artemis-2 and beyond. The larger tank will allow NASA to attempt SLS launches on three consecutive days, instead of opportunities two out of three days, in the event of a scrub. The newer technology reduces liquid hydrogen burn-off, allowing more launch attempts before having to refill the larger tank. Construction began in 2019 and will be complete prior to Artemis-2.
Orion Underway Recovery Test 8
The integrated recovery team of NASA, EGS, Lockheed Martin and the U.S. Navy, along with additional contractor support, will head out to sea off the coast of California in March to conduct the eighth Underway Recovery Test. Using a Navy ship with a well deck and several small boats, the primary objective is to validate Orion recovery operations for Artemis I — including procedures and timelines, and practicing different scenarios.
This spring, the Orion spacecraft for Artemis I will return from NASA’s unique test facility at Plum Brook Station in Ohio, where it is currently undergoing environmental testing inside the vacuum chamber that simulates the harsh environment of space. Inside the Neil Armstrong Operations and Checkout (O&C) Building at Kennedy, technicians will install the spacecraft’s solar array wings before performing final checkouts. EGS will begin Orion ground processing and stacking activities later in the year. The team will process and fuel Orion in the Multi-Purpose Processing Facility then transfer it over to the Launch Abort System Facility where engineers will attach the launch abort system. Orion will then roll out to the VAB for inspections before stacking Orion on top of the SLS rocket.
In its early processing stages, the Artemis II crew module milestones inside the O&C include propulsion tank installation, a pressure test and subsystems installations in the spring. The initial power-on of the crew module will occur in early fall. The heat shield that will protect the first crewed mission of Orion will be completed and installed by the end of the year. Processing and testing of the crew module adapter – the ring that connects to the European Service Module – for Artemis II will happen in the first half of the year prior to the arrival of the European Service Module in the fall.
SLS (Space Launch System)
Training activities with pathfinders, or full-scale replicas, of the SLS core stage and booster segments occurred in 2019, and more training with various pathfinder segments and hardware will continue. In 2020, training will involve stacking inert booster segments on the mobile launcher in the VAB.
Hardware for SLS will continue to arrive for processing and integration in various Kennedy facilities. This year all ten of the solid propellant booster segments will arrive by train from their Northrop Grumman manufacturing facility in Promontory, Utah. The launch vehicle stage adapter, which will connect the SLS core stage to the interim cryogenic propulsion stage, will arrive by barge. The booster aft skirts – which contain the thrust vector control system that steers the rocket – will trek from the Booster Fabrication Facility to the Rotation, Processing and Surge Facility where they will be attached to the aft exit cones. The exit cones are attached to the bottommost part of each of the twin boosters to provide extra thrust to the boosters and protect the aft skirts from the thermal environment during launch.
The core stage of the SLS rocket will undergo a Green Run test campaign over several months in the B-2 test stand at the agency’s Stennis Space Center in Mississippi. Following Green Run completion, the 225,000-pound core stage will leave Stennis and arrive at Kennedy on the Pegasus barge. The core stage and solid rocket boosters will then be integrated inside the VAB.
Mobile Launcher 2
In 2019, NASA awarded a contract for Mobile Launcher 2 to Bechtel National Inc. of Reston, Virginia. The ground structure that will be used to assemble, process and launch the second and more powerful configuration of the SLS rocket, called Block 1B, is in its early stages of design and development and will be ready for Artemis-4.
Artemis-1 will be the first in a series of increasingly challenging missions that will enable human exploration to the Moon and Mars. In 2020, the mission will truly begin to take shape as hardware arrives and stacking operations begin inside the VAB.
“The operations team is writing procedures, training, and preparing for flight hardware processing,” Bolger said. “When the SLS and Orion are turned over to EGS later this year, Kennedy will be ready!”
Future Artemis missions will establish a sustainable presence at the Moon for decades to come, and Kennedy teams will move forward in 2020 to build the infrastructure and make those missions possible.
• December 17, 2019: Europe will power the NASA spacecraft that take astronauts to a new international outpost and forward to the Moon, following decisions made by ESA Member States at Space19+ in Seville, Spain. 23)
- The decision by Member States show a strong commitment to progressing Europe’s exploration of the Solar System and will see ESA play a key role in Artemis missions by providing European Service Modules for Orion spacecraft three and four.
- The Orion spacecraft is built by NASA with ESA providing the service module. The arrangement stems from the international partnership for the International Space Station. NASA’s decision to cooperate with ESA on a critical element for the mission is a strong sign of trust and confidence in ESA’s capabilities.
- More than 20 companies around Europe are now building the European Service Module as NASA works on Orion and the Space Launch System.
- ESA is already providing the European Service Modules that will power missions one and two. The first Artemis mission will see Orion fly without astronauts around the Moon, with the second mission flying with astronauts on a direct return trajectory around the Moon.
- Under current Artemis planning, the third and fourth missions will see NASA’s Orion spacecraft bring astronauts to the Gateway and on to a landing on the lunar surface.
- The news confirms that humankind’s return to the Moon will be truly international, strengthening the collaboration between NASA and ESA on Orion, Artemis and much more.
- Space19+ results also give ESA mandate to start procuring ‘long-lead items’ that require more time to develop and build – allowing industrial partners to prepare early equipment needed for a fifth and sixth European Service Module.
- The first European Service Module is currently at NASA’s Plum Brook Station in Ohio, USA, coupled to the Crew Module and Service Module Adapter for thermal-vacuum and electromagnetic tests on the complete Orion spacecraft.
- The second European Service Module is being built in Bremen, Germany, by prime contractor Airbus. The structure is complete and technicians are working round the clock to complete the module, starting with integration of 11 km of wiring.
- NASA is committed to landing on the Moon by 2024 and Europe is now a trusted lunar partner, supplying the modules to propel Orion and support the astronauts with energy and consumables en route.
Figure 31: Exploration Mission-1 step-by-step. Orion is NASA’s next spacecraft to send humans into space. It is designed to send astronauts farther into space than ever before, beyond the Moon to asteroids and even Mars. ESA has designed and is overseeing the development of Orion’s service module, the part of the spacecraft that supplies air, electricity and propulsion. Much like a train engine pulls passenger carriages and supplies power, the European Service Module will take the Orion capsule to its destination and back (image credit: ESA–K. Oldenburg)
• December 4, 2019: Here at NASA’s Plum Brook Station in Ohio, USA, Orion is being put into a thermal cage in preparation of getting its first feel of space in the world’s largest thermal vacuum chamber. 24)
Figure 32: The Orion spacecraft with European Service Module at NASA’s Plum Brook Station. The first Orion will fly farther from Earth on the Artemis I mission than any human-rated vehicle has ever flown before – but first it will undergo testing to ensure the spacecraft withstands the extremes of spaceflight. In this figure, Orion is being placed in a cage, called the Thermal Enclosure Structure (TES), that will radiate infrared heat during the tests inside the vacuum chamber (image credit: ESA, S. Corvaja)
- Orion will be subjected to temperatures at Plum Brook ranging from –115°C to 75°C in vacuum for over two months non-stop – the same temperatures it will experience in direct sunlight or in the shadow of Earth or the Moon while flying in space.
- The tests that will be run over the next few months will show that the spacecraft works as planned and adheres to the strictest safety regulations for human spaceflight. The European Service Module has 33 thrusters, 11 km of electrical wiring, four propellant and two pressurization tanks that all work together to supply propulsion and everything needed to keep astronauts alive far from Earth – there is no room for error.
• November 27, 2019: Plum Brook Station is a remote test facility for the NASA Glenn Research Center in Cleveland, Ohio. Plum Brook is home to the world’s largest and most powerful space environment simulation facilities including the Space Simulation Vacuum Chamber. 25)
Figure 33: The Reverberant Acoustic Test Facility is the world's most powerful spacecraft acoustic test chamber, which can simulate the noise of a spacecraft launch up to 163 decibels or as loud as the thrust of 20 jet engines. The Mechanical Vibration Facility is the world's highest capacity and most powerful spacecraft shaker system, subjecting test articles to the rigorous conditions of launch. The Orion spacecraft and its European Service Module is tested here to ensure it will withstand the extremes of spaceflight (image credit: NASA)