Initial_Baseline_DSG-CONOP-001_06_2019.docx

DSG-CONOP-001

INITIAL BASELINE

National Aeronautics and Space Administration

RELEASE DATE: 06/01/2019

Gateway Concept of Operations

Date: June 1, 2019 Revision: Initial Baseline

Title: Gateway Concept of Operations

This document contains data within the purview of the United States (U.S.) Export Administration Regulations (EAR), 15 CFR 730-774, and is classified as EAR99/No License Required (NLR). The document may be used only in the International Space Station (ISS) program to fulfill responsibilities of the Parties or of a Cooperating Agency of an ISS Partner in furtherance of the ISS Intergovernmental Agreement. Re-transfer or disclosure to, or use by, any persons other than citizens of ISS Program International Partner countries, or use for any other purpose, requires prior U.S. Government authorization.

NASA and International Partner Internal Use Only • Do Not Distribute This document may only be released according to the Destination Control Statement on the front cover.

Revision and History Page

No.

Date

dated XX/XX/XX) June 1, 2019

Table of Contents Paragraph

Appendix

TAble

Figure

Introduction Background National Aeronautics and Space Administration (NASA) is faced with many challenges associated with building a sustainable presence beyond low Earth orbit. In order to meet some of these challenges, NASA will develop and operate a Gateway in lunar orbit, evolve lander capabilities to deliver payloads, and eventually humans on the lunar surface. To help solve the challenges of deep space exploration, NASA will rely on the knowledge within the agencies as well as reach out to the International Partners and domestic partners to ensure safe human presence. The Gateway will be placed in an area near the Moon, which is known as cislunar space, which offers a true deep space environment to gain experience for human missions to Mars. It offers NASA the ability to return to Earth if needed in days rather than weeks or months required for missions deeper into the solar system. The Gateway will provide NASA with a strategic presence and critical infrastructure in lunar orbit. From there, NASA and its partners will conduct ground breaking science and technology demonstration. This will allow a new era of exploration on the Moon and subsequent translation of that experience to human mission on Mars.

The Gateway is central to advancing and sustaining global human space exploration goals. It will serve as a unifying catalyst in our architecture for human deep space operations, lunar surface access, and missions to Mars.

The Gateway will begin a new era of space science, providing unique options for Earth science, heliophysics, lunar and planetary sciences, life sciences, astrophysics and fundamental physics investigations by allowing extended views of the Earth, Sun, Moon, and space not possible from the Earth's surface or from Earth orbit.

Purpose and Scope The purpose of this Concept of Operations (ConOps) is to define the operational capabilities of the overall Gateway and, in so doing, identify necessary system and module characteristics and functional responsibilities. This information then becomes a source for the development of system and module functions/requirements, which in turn becomes the structure for the design, development, and implementation of the actual spacecraft hardware. In this way, then, the ConOps is both a tool of communication and education but also distinctly a working document.

The scope of this Gateway ConOps is defined as the aggregation, operations, and utilization of the Gateway spacecraft in cislunar space. The Gateway ConOps is informed by HEOMD-005, The Human Exploration Operations Mission Directorate Exploration Design Concept of Operations. This higher-level document provides the umbrella description of the overall concept for human exploration in fulfillment of agency mission objectives. Further, the information in the Gateway ConOps is supplemented by, DSG-ADD-001, Gateway Architecture Definition Document, DSG-ANA-001, Gateway Functional Allocation, and discipline detailed ConOps. The Gateway ConOps will eventually be superseded by operational plans/procedures, and flight rules. Figure 1.2-1, Gateway ConOps Information Flow, represents how the ConOp influences or is supplemented by other products.

Figure 1.2-1 Gateway ConOpS Information Flow Documents Applicable Documents The following documents include specifications, models, standards, guidelines, handbooks, and other special publications. The most current version of the documents listed in this paragraph is applicable to the extent specified herein.

Reference Documents The following documents have been used to inform this ConOps or may serve as useful references for further understanding of the mission, operations, and modules of the proposed Gateway.

Interface Definition Document (IDD)

Concept Overview The concept for the Gateway is that it provides a lunar orbiting platform in cis-lunar space with the primary capabilities to:

a) Focus on infrastructure and systems that will allow autonomous vehicle operations aboard the Gateway with robotics, automated systems, advanced communications, and distributed computing.

b) Allow two to four person crew expeditions approximately once per year, although the frequency could increase if additional crew transportation systems become available.

c) Support crew expeditions for a minimum of 30 days, while not precluding increased durations based on augmented system capabilities, logistical capabilities, etc.

d) Transfer the uncrewed Gateway back and forth between Near-Rectilinear Halo Orbit (NRHO) and other lunar orbits in order to provide opportunities for additional technology demonstrations or scientific investigations.

e) Allow delivery of payloads to the Gateway by logistic resupply spacecraft, Gateway modules, or crewed visiting vehicles. Also to allow delivery of lunar samples and scientific experiments to Earth aboard crewed visiting vehicles or reusable logistics resupply spacecraft.

f) Provide unique options for Earth science, heliophysics, lunar and planetary sciences, life sciences, astrophysics and fundamental physics investigations through extended views of the Earth, Sun, Moon, and space.

g) Serve as a platform to demonstrate the necessary capabilities to expand a sustainable human presence into deep space including the surface of the Moon and Mars.

Figure 3.0-1, Gateway ConOps, highlights the various capabilities/operations the Gateway will offer while satisfying the overall mission/utilization objectives.

Figure 3.0-1 Gateway CONOPs Gateway Objectives In preparation for human missions to the lunar surfaces and other deep space destinations, it is essential that the Gateway meet a core set of objectives while providing infrastructure for the next phases of human exploration referenced in HEOMD-001, Human Exploration and Operations Exploration Objectives.

The Gateway objectives are:

a) Support human exploration beyond Earth.

b) Provide a staging point that can be used for multiple missions both to the Moon and beyond, enabling reusable in-space systems.

c) Enable a regular cadence of human crewed missions to cislunar space including capabilities that enable lunar surface mission.

d) Provide capabilities to meet scientific requirements for lunar discovery and exploration, as well as other science objectives, as appropriate.

e) Demonstrate and validate technologies that are enabling for lunar missions and feed forward to Mars as well as other deep space destinations.

f) Demonstrate the systems and operational capabilities required for crewed missions beyond the Earth-Moon system.

Gateway Utilization Gateway utilization is defined as the extent to which the Gateway resources and capabilities are used to achieve objectives, including exploration, science, commercial, and international. The more objectives that are achieved with the Gateway, the more the Gateway is considered to be utilized. The Gateway is designed to support a variety of utilization activities during both crewed and uncrewed periods and is planned for continuous operations throughout its lifetime. These operations include demonstration of key exploration capabilities in a relevant deep space environment, conducting science beyond the influence of Earth, and providing opportunities for Gateway partners and customers for deep space exploration. There may be cases on Gateway where a demonstrated capability becomes part of the nominal operations. Located in cislunar orbit, the Gateway capabilities can be further leveraged to enhance lunar and Mars exploration.

The Gateway will accommodate payloads both internally and externally. A broad range of Gateway resources will be available for use, to include power, thermal, internal and external attachment interfaces, stowage volumes, docking ports, communications, video, data storage, and monitoring through ground control centers. The Gateway will provide adequate resources while the crew is there during a given mission for utilization as well as an architecture that can also support utilization operations while uncrewed. As a result, the Gateway architecture will need to blend crew, flight operations, automation, science airlock, internal/external robotics capabilities, Extravehicular Activity (EVA), and lunar communications. Gateway architecture will support robotic missions and robotic telepresence that are extensible to Mars exploration. The Gateway will support multiple approaches for payload transport to/from the Gateway. These approaches for new payloads include the use of visiting vehicles, logistics modules, and within other Gateway modules. The use of Orion for payloads will require cross program coordination and agreements to establish the capabilities that will be available for this purpose. The allocations available for these resources are defined in Gateway requirements DSG-RQMT-001, Gateway Requirements Document. The availability of the resources and capabilities during Gateway construction are outlined in HEOMD-006, the Exploration Utilization Plan.

The Gateway offers an opportunity to begin a new era of space science, providing unique options for Earth science, heliophysics, lunar & planetary sciences, life sciences, astrophysics and fundamental physics investigations by allowing extended views of the Earth, Sun, Moon, and space that are not possible from the Earth's surface or from Earth orbit. Externally mounted experiments will collect samples and provide important science about cometary material, solar composition, interstellar particles, and near Earth objects. Small satellites can be released from the Gateway <TBR-GTW-CONOP-009>, with the Gateway providing a communications relay. All of these activities greatly expand the scope of science that can be conducted in cislunar space and the number of scientists involved in exploration. The Gateway will simplify missions to collect planetary (i.e. Mars) and asteroid samples, within planetary protection regulation allowing samples, with proper containment, to be returned to the Gateway for transportation back to Earth. NASA and its partners will also develop progressively complex robotic missions to the surface of the Moon, achieving scientific and exploration objectives in advance of a human return to the lunar surface. As part of these activities, astronauts will be able to control robots from the Gateway via near-real-time telepresence, dramatically improving the return from these assets.

The Gateway will provide opportunities for both United States (U.S.) Commercial and International Partners to participate in exploration beyond Earth. Opportunities could range from the supply of utilization payloads and/or logistics to the provision of entire modules of the Gateway. International partnerships have been a vital component of space exploration, allowing partners to target individual objectives while working together to achieve greater and more collaborative goals. Following the commercial model that the agency pioneered in low-Earth orbit for space station resupply, NASA plans to resupply the Gateway through commercial cargo missions and internationally contributed cargo missions. Commercial spacecraft could also dock to the Gateway between crewed missions to conduct other activities. Additional potential exists for a commercially-provided crew to visit the Gateway. The Gateway will be designed with standard interfaces, encouraging all partners to leverage its capabilities and improves competition for the benefit of space exploration.

Additional utilization details can be found in <TBD-GTW-CONOP-006>, Gateway Utilization Concept of Operations.

Gateway Architecture The concept of the Gateway architecture is an assembly that is composed of several modules developed as shown in Figure 3.3-1, Gateway Architecture. These modules are launched either as co-manifested payloads on the Space Launch System (SLS) along with the Orion crew vehicle or on Commercial Launch Vehicles (CLV)s. The modules combined into the Gateway architecture represent a meaningful series of demonstration steps in the direction of enabling a more extensive exploration effort in the future.

Figure 3.3-1 Gateway Architecture To maximize Gateway interoperability, consistent with the staggered, incremental assembly sequence, and enable effective response to any real time on-orbit anomalies and/or failures, the Gateway architecture will allow sharing of resources (such as: integrated power distribution/management; integrated vehicle system health and status monitoring/data processing and systems management; thermal control; command and data handling; communications; and Environmental Control and Life Support System (ECLSS) for pressurized modules) across module interfaces. Each module will have its own Module System Manager at the same hierarchical level under overall supervision of the Gateway Vehicle System Manager. A series of Subsystem Interoperability Standards have been generated to improve consistency amongst the Gateway modules and other compliant deep space vehicles. The Gateway modules will also provide common mechanical, power, data, and communication interfaces to support attached, external equipment and payloads, as well as contingency EVA maintenance and repair operations. The crew will be able to perform, either directly or remotely, from within Gateway habitable modules: command/control and communication functions, external robotic system operations; as well as nominal and off-nominal control of life support, thermal control, and other system functions necessary for safe operations. Safe operations for Gateway are consistent with NASA human-rating policy and HEOMD requirements. Cross strapping capability will exist as part of the nominal configuration on the internal thermal control systems for the habitation modules that are connected across the module interfaces (via NDS/IDSS). However, this capability will be used only for contingency cases by opening a normally closed valve to provide inter-module fluid flow. Two adjacent modules will have the capability to share thermal resources, but each module will only provide that function to a single adjacent module at any one time.

Additional capability details for the individual and combined modules are provided through out this ConOps, primarily in the assembly operation sections describing when the module is added to the Gateway stack.

For a full summary of the Gateway architecture details (and individual modules) see DSG-ADD-001, a brief summary of the Gateway module capabilities are listed below:

Power and Propulsion Element The Power and Propulsion Element (PPE) provides the capability to generate power for the Gateway, transport Gateway between cislunar orbits, perform orbital maintenance, provide attitude control for the Gateway in multiple configurations, provide communication (to and from Earth, space to space communication, space to lunar communication, and relay EVA communication to Earth), and accommodations for external utilization.

European Space Agency System Providing Refueling Infrastructure and Telecommunications/U.S. Utilization Module The European System Providing Refueling Infrastructure and Telecommunications (ESPRIT)/United States-Utilization Module (US-UM) are two modules that are integrated as one launch package as the ESPRIT/US-UM or (E/UM).

The ESPRIT is an International Partner contribution to the Gateway that provides the capabilities of fuel storage and refueling (xenon and hydrazine propellant) for PPE, a science airlock to facilitate experiments in deep space, direct Lunar communication to/from lunar surface, backup communication to Earth for the Gateway, and external utilization accommodations.

The US-UM provides the capabilities for early habitable utilization of the Gateway, internal and external payload accommodations, external robotic interfaces, power and thermal control, oxygen/nitrogen supply and air circulation, and logistics storage for crew consumables.

Habitation Modules The Habitation Modules (HAB) are where the astronauts will live and work. With the intention of using the Gateway as a technology demonstration activity to enable future, more ambitious missions, the HABs provide life support for the crew to perform science/utilization, maintain and conduct crew health and performance/medical operations, as well as pressurized cargo and logistics stowage.

Habitation functionality will be distributed across the US-UM and two HABs. The Gateway will have two HAB modules an International Partner Habitation Module (I-HAB) and a United States-Habitation Module (US-HAB). Each HAB can provide core capabilities (primary distributed systems and externally mounted hardware), with additional outfitting (laptops, portable equipment, crew support systems (medical, exercise, crew quarters, toilet), Intravehicular Robotics (IVR) and Extravehicular Robotics (EVR) command and control system) to be accomplished using Logistics Modules.

Logistics Module The Logistics Module (LM) provides the capability to deliver pressurized and unpressurized cargo to the Gateway enabling extended crew mission durations, science utilization, exploration technology demonstrations, potential commercial utilization, system outfitting and other necessary supplies. LMs may or may not be permanent fixtures of the Gateway and will depend on individual module configurations. LM deliveries will be driven by mission needs.

Deep Space Exploration Robot The EVR provides the capability to deploy and retrieve external utilization payloads, utilize the science airlock to retrieve/deploy payloads, inspect the Gateway system, berth of robotic spacecraft, support contingency maintenance, support self-maintenance of robotic components in the science airlock, and support EVA crewmembers.

The EVR, is provided by Canadian Space Agency, that will be delivered on a LM and be able to be activated and walk off onto Gateway by remote ground commanding and without EVA assistance. The robotic arm will have the capability to translate along the Gateway infrastructure, by walking to grapple fixtures placed externally along the Gateway modules.

Airlock The Airlock provides the capability to enable crewed EVAs, accommodate EVA suit/tool storage, accommodate pre-EVA checkout and preparations to include prebreathe protocols, accommodate post-EVA activities, as well as accommodate demonstration of future EVA technologies.

Associated Capabilities In order to make the Gateway possible, there are a number of necessary associated capabilities and services to get the Gateway architecture pieces from Earth into the target orbit, support crew visits, and allow remote operations. These capabilities and services include ground processing, launch facilities, launch vehicles, crew vehicles, and flight operation centers. Details of the specific interfaces between the Gateway and these associated capabilities are summarized in DSG-PLAN-014, Gateway Interface Management Plan and specific interface documents.

Ground Systems Ground Systems provide common infrastructure and services to perform preflight processing, launch, and recovery of flight elements, flight crew, payloads and/or cargo. Gateway modules and payload teams would reach out to different ground systems organizations for the following capabilities to support Gateway module/launch vehicle integration: receiving, ground processing, integration, integrated and interface testing, vehicle servicing, and launch operations.

Standalone processing activities include all final preparations and tests done at the launch site prior to turnover for integration to the launch vehicle. These will be performed by Gateway Element teams and will typically occur at Kennedy Space Center’s (KSC) Space Station Processing Facility (SSPF) utilizing the services of the Gateway Payload Processing Integrated Product Team.

For Gateway modules that will utilize NASA's Exploration Ground Systems (EGS) located at the Kennedy Space Center in Florida, a detailed description of the ground processing capabilities as well as the ground ConOps can be found in GSDO-ACO-1010, Ground Systems Development and Operations Program Architectures and Concept of Operations Document.

For Gateway modules that utilize a commercial ground system, a detailed description of the ground processing capabilities as well as the ground ConOps can be found from the specific commercial provider documentation.

Plans for launch site processing and packing of cargo, utilization payloads, consumables, supplies, spares, etc. are <TBD-GTW-CONOP-008>.

Launch Vehicles Launch vehicles provide the capabilities and services that get the Gateway modules from Earth to a designated space orbit. The launch vehicle service will integrate the Gateway modules as a payload into the launch vehicle and provide adapters, fairings, separation systems, and provide the agreed to capabilities (power, thermal, communication, etc.) between the payload (Gateway module) and the launch vehicle from launch to the designated orbit.

SLS Launch Vehicle NASA's SLS vehicle Block 1B configurations, shown in Figure 3.4.2.11, SLS Launch Vehicle, will be used for delivering several of the Gateway modules.

Figure 3.4.2.1-1 SLS Launch Vehicle

SLS Block 1B will support the ability to launch a crewed Orion with a co-manifested payload (Gateway module). SLS Blocks 1B will utilize an Exploration Upper Stage (EUS) to deliver the Co-Manifested Payload (CPL) (Gateway module) to cislunar Orbit. Details of the SLS payload accommodations, that define the boundary conditions for the CPL, can be found in ESD 30000, SLS Mission Planning Guideline, and details of SLS mission can be found in the SLS-PLAN-020-02, Space Launch System Program (SLSP) Concept of Operations (ConOps) Volume 2: Block 1B Vehicle.

Commercial Launch Vehicle For Gateway modules that utilize a CLV, a detailed description of the launch vehicle capabilities can be found from the specific commercial provider documentation.

Crewed Visiting Vehicle Crewed visiting vehicles provide the capability to transport crewmembers from Earth to the Gateway and return to Earth. The crewed visiting vehicle will also provide the capabilities to protect the crew during launch or inflight aborts, emergency termination of the mission, and limited reaction to contingency and emergency situations.

During assembly, if Gateway modules are a CPL on SLS then the Orion crewed vehicle will specifically be used to transport the crew and Gateway modules to the Gateway stack. During the transport, Orion will provide some basic services like power, data, and communication (for health/status, and Rendezvous Proximity Operations and Docking (RPOD)) for the Gateway module. The Orion Multi-Purpose Crew Vehicle (MPCV), as shown in Figure 3.4.3-1, Orion Crew Vehicle, is a pressurized vehicle that transports up to four crewmembers, from the Earth's surface to their destination and brings the crewmembers safely back to the Earth's surface at the end of a mission. Note: Figure 3.4.3-1, shows the full Orion system that is launched.

Figure 3.4.3-1 Orion Crew Vehicle The Orion consists of a Crew Module that provides habitable pressurized volume to support crewmembers and cargo, a Service Module that provides propulsion, consumables storage, heat rejection and power generation, a Spacecraft Adaptor and a Launch Abort System. The Orion, independently, provides all the necessary support for the crewmembers for up to twenty-one day missions. Additional details of Orion can be found in MPCV 72093, Multi-Purpose Crew Vehicle (MPCV) Program Concept of Operations (ConOps)Document.

Other commercial or international crewed visiting vehicles may be utilized to transport crew from Earth to Gateway, but must provide similar attributes as Orion in order to comply with human rating for the integrated Gateway-visiting vehicle system.

The Orion crewed vehicle is the only visiting vehicle planned to be used during assembly operations to conduct in-Space transit for Gateway modules, from launch vehicle extraction to docking with the Gateway stack. Detailed definitions, characteristics, and constraints of the interface with Orion is captured in MPCV 72633, Orion Multi-Purpose Crew Vehicle (MPCV) Interface Definition Document (IDD).

Flight Operations The Flight Operations support is a scalable, evolvable capability to perform flight operations for all exploration flight elements. Flight Operations provides the functions necessary to enable mission execution, develop mission timelines, procedures, flight rules, Launch Commit Criteria inputs, etc., train flight controllers and crews, and command/control/track/monitor vehicle systems and navigation during flight operations. The Mission Control Center (MCC), located at the Johnson Space Center in Texas, has the capability to conduct flight operations including command, control, planning, reconfiguration and coordination with external interfaces (e.g. Department of Defense elements, Space/Ground Networks, International Space Station (ISS)). International and Commercial partners may establish other control centers with the same functionalities or a subset thereof, according to the ground segment concept jointly developed by the partners.

Payload Operations The Payload Operations support is a scalable, evolvable capability to perform science operations for all Gateway utilization experiments. Payload Operations provides the functions necessary to integrate experiments, perform payload interface testing, plan utilization, train payload flight controllers and crews, as well as command, control, track, and monitor payload systems and experiments during flight operations. A Payload Operations and Integration Center, located at the Marshall Space Flight Center in Alabama, has the capability to conduct payload operations including experiment command, control, planning, reconfiguration and data/imagery/video distribution to remote researchers (e.g. telescience centers or other researcher facilities). International and Commercial partners may establish other payload operation centers or solutions to interact with their payloads if not utilizing the Payload Operations and Integration Center in Alabama.

Communication Network(s) The communications architecture for human space exploration is driven by specific operations, concepts and required mission capabilities. Functional drivers include real-time mission command/imagery/telemetry, downlink of recorded data/video to support operations, system health status, catastrophic failure analysis, recovery needs, education and public outreach objectives, individual crewmember engagement, crewmember health and medical status, and flight certification of modules. Exploration modules will utilize the Space Communication and Navigation (SCaN) Networks to provide the key communications capabilities: Near Earth Network (NEN), Space Network (SN), Deep Space Network (DSN) as well as augment coverage with other commercial and international partner ground stations as needed. Details of the Gateway communications are found in section 5.3.

Cislunar Orbit Location The Gateway will operate in a cislunar halo orbit that, in operation, functions like a high orbit in the Earth-Moon system. The established reference orbit for the Gateway is a NRHO in the Earth-Moon system. The NRHO meets the needs of the initial reference mission to provide habitat conditions (thermal, propulsion and power requirements, and communications), access by crewed and logistics launches (including considerations for aborts), and potential access to the lunar surface, demonstrated that the NRHO met the needs for the initial reference for the mission. Other orbits such as Distant Retrograde Orbits (DRO), L1 or L2 Halo Orbits were also assessed.

Figure 3.5-1, Gateway NRHO, is an illustration showing the NRHO for Gateway. The NRHO (L2 South) dashed line in the left-hand image represents the spacecraft orbit while the solid Earth/Moon line show trajectories of entry and departure from the NRHO. The right-hand image shows that there are actually four potential NRHOs from which to choose. Gateway primary orbit is the L2 South NRHO, as the reference orbit described in DSG-ADD-005, Gateway Integrated Performance Assessment and supporting analysis information in DSG-DDD-002, Gateway Mission Design Document.

Figure 3.5-1 Gateway NRHO In order to be solar neutral, the x-axis of the stack needs to be pointed either towards the sun or away from the sun as shown in Figure 3.5-2, Gateway Orientation. This solar-neutral attitude is described as a Solar Pressure Equilibrium Attitude (SPEA). The preferred SPEA direction for Gateway is +x to sun. This also positions crewed visiting vehicle tail-to-sun to minimize crewed visiting vehicle thermal issues, and maximize time crewed visiting vehicle solar arrays are sun pointing.

Figure 3.5-2 Gateway Orientation

Use of SPEA in an NRHO places constraints on the Earth high-gain antenna to track Earth's relative location with respect to the sun. Potential stack blockages can be addressed through a combination of pitch and roll maneuvers. The Gateway design concept for thermal management is agnostic to flight attitude. During orbit transfers SPEA may need to be adjusted in order to orient the electric propulsion engine in the required direction. In that scenario, use of vehicle roll and array gimbaling will be used to provide adequate power and maintain attitude control. In summary, SPEA has been identified as a favorable reference attitude for Gateway in the NRHO and for coasting arcs during orbit transfers.

Gateway Design Reference Missions SLS Block 1B Orion Crewed Module Transport to the Gateway (Crewed Cislunar Operations (Orion dependent CPL)) This Design Reference Mission (DRM) is a crewed mission using a SLS Block 1B to deliver Orion and a dependent co-manifested Gateway element to the Gateway destination orbit. The representative CPL chosen for this DRM is a Gateway HAB. For the purposes of this DRM, a HAB module represents a boundary-case class of payloads that could be flown to develop capabilities and information for future exploration missions.

Launch, ascent, and proximity operations with a dependent CPL are covered in subsections of section 4.1. During transit, the HAB provides thermal control for itself, using power from its own storage and power from Orion. Orion also provides attitude control and translational capability for the combined Orion/HAB stack. Orion, docked with the HAB, performs a translational burn to accomplish a powered lunar flyby gravity assist maneuver that targets the NRHO. At NRHO arrival, Orion then performs a translation burn to establish the NRHO orbit as part of the maneuvers to enable the Orion/HAB to rendezvous with the Gateway, which is already in the NRHO.

Prior to arriving at the NRHO, Orion and Flight Operations determine the HAB is ready for ingress. Orion conducts rendezvous, proximity, and docking operations as the chaser vehicle with the target Gateway. Orion maneuvers the HAB to the conditions required for docking with the Gateway and the Orion/HAB completes the docking operations between the HAB and the Gateway. After docking the HAB to the Gateway, the crew then sequentially equalizes pressures between Orion and the HAB, and opens hatches for ingress to the HAB. Gateway provides ECLSS functions for the joint volume (including consumables) and Gateway provides a fan for air exchange between the Orion and Gateway. The pressure equalization and ingress process is repeated between the HAB and the Gateway.

Gateway performs attitude control of the docked stack.

Orion spends several days docked to the Gateway at the NRHO. As the end of the docked mission is reached, the crew prepares the Gateway for uncrewed operations. Deep space systems are reconfigured as needed to enable commanding from flight operations in the absence of crew, as well as monitoring of experiments and observations which continue after the crew departs. At the conclusion of the docked mission, Orion undocks from the HAB and separates from the Gateway. Orion then executes a departure burn, which targets the RPF conditions to send the vehicle on a transit back to Earth.

An overview of the Crewed Cislunar Operations with the co-manifested HAB Module DRM is shown in Figure 3.6.1-1, Dependent CPL DRM.

Figure 3.6.1-1 Dependent CPL DRM International Partner-Provided or U.S. Commercial Launch Vehicle Autonomous Module Delivery DRM This DRM is a launch of LM on a launch vehicle other than SLS. The LM has its own power, propulsion, communication, and navigation system so it makes the journey to cislunar orbit using its own systems. This DRM may apply to other robotic autonomous elements of similar mass, volume, and flight capability. Logistics modules may be launched on International Partner provided or U.S. commercial launch vehicles and perform autonomous flight to rendezvous with the Gateway in cislunar orbit. Launch and analysis of the trajectory from an external provider would be the responsibility of the module supplier. However, upon arrival in the vicinity of the Gateway flight operations would assume the responsibility for integrated operations to support rendezvous, proximity operations, and docking or berthing. Once attached, the initial activation of the module includes checkout of the systems, communication capability, and avionics interfaces. To drive in-space performance requirements, this DRM assumes a ballistic lunar transfer such that the launch, ascent, and transit to destination would take on the order of 150 to 200 days for missions to NRHO; other mission-specific trajectories are possible, but this is likely an upper-bound of transit duration. During this time, the LM is controlled and monitored from the ground via a compatible network.

Prior to docking, checkout of the Automated Rendezvous and Docking systems is performed from the ground. The docking mechanism is exercised by issuing commands through each redundant string to perform checkout of the various system components.

After the transit to the target orbit maneuvers have taken place, the LM reaches the orbit insertion location within approximately 100 km of the target spacecraft. The LM and target spacecraft perform rendezvous and complete the docking operations. The crew and/or IVR configure the LM for docked operations. New supplies are offloaded from the LM to the Gateway by EVR, IVR, or crew from a later crewed visiting vehicle. Items to be discarded from the Gateway are stowed in the LM. When ready for disposal, the crew and/or IVR prepare the LM for jettison operations.

When ready for jettison, the LM is commanded, by flight operations, to undock followed by execution of a safe disposal.

An overview of the Commercial Launch Vehicle Operations with the Logistic Module DRM is shown in Figure 3.6.2-1, Commercial DRM <TBD-GTW-CONOP-010>.

Figure 3.6.2-1 Commercial DRM <TBD-GTW-CONOP-010> Uncrewed Transfer of Gateway Trajectory between Cislunar Orbits DRM The Gateway destination orbit is the NRHO. During uncrewed periods, the Gateway may embark on orbit transfers from the NRHO to other cislunar orbits. This DRM describes a set of candidate orbit transfer options that have been analyzed for transfer from NRHO to the following orbits:

a) DRO

b) EML 2

c) NRHO S to NRHO N The three cislunar transfer trajectories presented in these sections are summarized in Table 3.6.31, Transfer Trajectories. Note that values in Table 3.6.3-1 assume a 24.5 ton stack. These are included here for context and not intended to be indicative of specific requirements. As design and mission evolution occurs and these values and transit durations vary.

Table 3.6.3-1 Transfer Trajectory One-Way Transfer

26.6 kW power to the EP system

Distant Retrograde Orbit Target Orbit One target orbit considered as a potential target orbit for Gateway transfers in cislunar space is a DRO with a radius of about 70,000 km. Considered long term stable on the order of >100 years with only small variations in its orbit over time, this orbit could be considered as a candidate disposal orbit for Gateway.

This trajectory is shown in Figure 3.6.3.1-1, NHRO to DRO One-Way Representative Transfer Orbit. The NRHO starting orbit is colored in green, and the final DRO is shown in red.

Figure 3.6.3.1-1 NHRO to DRO One-Way Representative Transfer Orbit With an initial low thrust propulsion burn lasting 3.4 days, the PPE stack departs the NRHO and leaves the immediate lunar vicinity. During its transit around the Earth the PPE performs three additional low thrust propulsion burns. A majority of the time spent away from the moon is spent coasting. Upon return to near lunar vicinity, the trajectory performs two close lunar flybys before a 10.9 day low thrust propulsion burn to capture into the DRO. A summary of the burn and coast durations during this transfer is provided in Table 3.6.3.1-1, Trajectory Details for NRHO to DRO Transfers.

Table 3.6.3.1-1 Trajectory Details for NRHO to DRO Transfers

MISSION SEGMENT DURATION (DAYS)

EML2 Target Orbit Another target orbit considered as a cislunar transfer destination is a halo orbit about the Earth-Moon Lagrange Point L2 (EML2). There are several families of halo orbits about the EML2. The one targeted in this analysis is described as flat with respect to the Earth’s ecliptic plane. The flat L2 halos are chosen for their attractiveness as a staging orbit to other destinations. Because they are unstable orbits, they have stable and unstable manifold trajectories that can provide low-cost transfers to Earth, other orbits in Cislunar space, and beyond.

This trajectory is shown in Figure 3.6.3.2-1, Transfer from NRHO to EML2. The NRHO starting orbit is colored in green, and the final EML2 halo orbit is shown in red.

Figure 3.6.3.2-1 Transfer from NRHO to EML2 For the cislunar transfer to the flat EML2 halo orbit, a small low thrust propulsion burn lasting only 0.6 days is done by the PPE to escape the NRHO. Due to the flatness of this halo orbit with respect to the Earth-Moon rotating frame, in order to align itself for a minimum △V capture, the PPE stack makes several transits around the earth prior to the EML2 capture burn. To accomplish this re-alignment the PPE stack performs three low thrust propulsion burns prior to a 2.8 day low thrust propulsion burn to capture into the EML2 halo orbit. A summary of the burn and coast durations during this transfer is provided in Table 3.6.3.2-2, Trajectory Details for NRHO to Flat EML2 Transfer.

Table 3.6.3.2-2 Trajectory Details for NRHO to Flat EML2 Transfer Mission Segment Duration (days)

NRHO S to NRHO N This cislunar transfer, takes a total of 72 days, with 23 days of thrust and 49 days of coast. The trajectory is shown in Figure 3.6.3.3-1. Transfer From NRHO South to NRHO North.

Figure 3.6.3.3-1 Transfer From NRHO South to NRHO North Gateway-Supported Robotic & Human Lunar Surface Operations

<TBD-HEOMD-005-038>

Uncrewed Gateway Maintenance

<TBD-GTW-CONOP-001>

Extensibility The Gateway provides standard interfaces and complies with Interoperability Standards therefore allowing the capability for Gateway to extend beyond its assembly complete architecture and vision. If visiting vehicles comply with the interface and interoperability standards also then they can be utilized to extend the Gateway capabilities. For instance the Gateway could provide resources through the applicable interface for Sample Return Vehicles that bring back samples from the Moon.

Design reference mission details are found in section 3.6 Gateway Design Reference Missions Human Lunar Lander Extensibility The Gateway is capable of being an aggregation and staging platform for a human lunar lander vehicle and crew. The Gateway can provide resources before, during, and between lunar missions based on available ports, to allow the staging for a human lunar lander vehicle as long as the human lunar lander vehicle complies with IDSS compliant docking interface and interoperability standards.

Gateway can support the human lunar lander vehicle with the following capabilities:

a) Provide a node to transfer of crew and logistics to and from the human lunar lander vehicle.

b) Provide interface resources while docked (power and data).

c) Provide available docking port(s).

d) Provide communication between Gateway and the human lunar lander vehicle during the mission.

e) Provide EVR inspection

f) Provide EVR relocation and berthing Robotic Lunar Lander Extensibility The Gateway is capable of being an aggregation and staging platform for a robotic lunar lander vehicle.