DSG-RQMT-001.pdf

DSG-RQMT-001

BASELINE

National Aeronautics and Space Administration RELEASE DATE: JUNE 27, 2019

GATEWAY SYSTEM REQUIREMENTS

Approved for Public Release

This document has been approved for Public Release per DAA #71173 pending organizational review.

Revision: Baseline Document No: DSG-RQMT-001 Release Date: June 27, 2019 Page: 2 of 142 Title: Gateway System Requirements

This document may only be released according to the Destination Control Statement on the front cover.

REVISION AND HISTORY PAGE

Revision No.

Change No.

Description Release Date

Baseline DSG- C0017 Initial Release (Reference DSG-D0017) June 27, 2019

I I

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TABLE OF CONTENTS

1.0 INTRODUCTION

1.1 Scope & Purpose

1.2 Change Authority/Responsibility

1.3 Convention and Notification

1.4 Measurement Units

2.0 DOCUMENTS

2.1 Applicable Documents

2.2 Technical Authority Standards and Requirements

2.3 Reference Documents

2.4 Order of Precedence

3.0 DESCRIPTION AND REQUIREMENTS

3.1 System Descriptions and Design Considerations

3.1.1 System Definition

3.1.2 System Description

3.1.3 Human Rating Certification

3.1.4 Design Considerations

3.1.5 Gateway Functional Diagram

3.1.6 Interface Description

3.2 Requirements

3.2.1 Design Constraints

3.2.2 Mission Design

3.2.3 Integrated Performance

3.2.4 Guidance, Navigation & Control

3.2.5 Propulsion

3.2.6 Communications

3.2.7 Vehicle System Manager

3.2.8 Flight Software

3.2.9 Avionics

3.2.10 Power

3.2.11 Imagery

3.2.12 Environmental Control and Life Support

3.2.13 Thermal

3.2.14 Structures and Mechanisms

3.2.15 Safety

3.2.16 Human Systems

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3.2.17 Crew Systems

3.2.18 Extravehicular Activity

3.2.19 Extravehicular Robotics

3.2.20 Intravehicular Robotics

3.2.21 Utilization

3.2.22 Logistics

3.2.23 Reliability

3.2.24 Maintainability

3.3 Constraints

3.3.1 Environmental Conditions

3.3.2 Design and Construction Standards

3.4 External Interfaces

3.4.1 Visiting Vehicles

3.4.2 Ground Segment

3.5 Internal Interfaces

3.6 Reserved

3.7 Reserved

4.0 VERIFICATION

4.0 Qualification Provisions

4.1 Verification Matrix

4.2 Description and Verifications

4.2.1 Methods

4.2.2 Terminology

APPENDIX A ACRONYMS, AND ABBREVIATIONS AND GLOSSARY OF TERMS

A1.0 ACRONYMS AND ABBREVIATIONS

A2.0 GLOSSARY OF TERMS

APPENDIX B OPEN WORK

B1.0 TO BE DETERMINED

B2.0 TO BE RESOLVED

APPENDIX C ALLOCATION MATRIX

APPENDIX D VERIFICATION MATRIX

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TABLE OF TABLES

TABLE 2.1-1 TYPE 1 APPLICABLE DOCUMENTS

TABLE 2.2-1 TYPE 2 TECHNICAL AUTHORITY DOCUMENTS

TABLE 2.2-2 TYPE 3 TECHNICAL AUTHORITY DOCUMENTS

TABLE 3.2.3-1 GATEWAY MODULE LAUNCH MASSES

TABLE 3.2.6-1 DATA DOWNLOAD VOLUME TO EARTH

TABLE 3.2.10-1 GATEWAY POWER ALLOCATION

TABLE 3.2.10-2 EVR POWER ALLOCATION

TABLE 3.3.2-1 TYPE 2 TECHNICAL STANDARDS <TBR-L2-GW-057>

TABLE 3.3.2-2 TYPE 2 TAILORED TECHNICAL STANDARDS <TBR-L2-GW-058>

TABLE B-1 TO BE DETERMINED

TABLE B-2 TO BE RESOLVED

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1.0 INTRODUCTION

1.1 SCOPE & PURPOSE

This specification establishes the performance and design requirements for the Gateway as allocated from Human Exploration and Operations Directorate Requirements, HEOMD-004.

Requirements in section 3.2 define the performance of the Gateway as a whole. Requirements in sections 3.3 through 3.6 are constraints with which the Gateway must comply. The performance requirements herein are applicable during nominal operations, maintenance, and contingency events. This document is applicable to the assembly and assembly complete stage of the Gateway.

1.2 CHANGE AUTHORITY/RESPONSIBILITY

Proposed changes to this document shall be submitted via a Change Request (CR) to the Gateway Program Control Board (GPCB) for consideration and disposition.

All such, requests will adhere to the Gateway Configuration Management Change Process documented in DSG-PLAN-004.

The appropriate National Aeronautics and Space Administration (NASA) Office of Primary Responsibility (OPR) identified for this document is the Gateway Vehicle Systems Integration (VSIO) Requirements Development Team.

1.3 CONVENTION AND NOTIFICATION

The Gateway Program defines its implementation of requirement verbs as follows:

a. “Shall” – Used to indicate a requirement that is binding, which must be implemented and its implementation verified in the design.

b. “Should” – Used to indicate good practice or a goal which is desirable but not mandatory.

c. “May” – Used to indicate permission.

d. “Will” – Used to indicate a statement of fact or declaration of purpose on the part of the government that is reflective of decisions or realities that exist and are to be taken as a given and not open to debate or discussion.

e. "Is” or “Are” – Used to indicate descriptive material.

Rationales, included for many of the requirements, are intended to provide clarification, justification, purpose, and/or the source of a requirement. In the event that there is an inconsistency between a requirement and its rationale, the requirement always takes precedence.

1.4 MEASUREMENT UNITS

The Gateway Program will utilize NIST SP811, Guide for the Use of the International System of Units (SI) for standardization and conversion of the units of measure.

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2.0 DOCUMENTS

For the purpose of this document, the term ‘document’ can also refer to ‘digital artifacts,’ ‘models,’ or ‘viewpoints’ as needed to convey and exchange configuration managed data or information. An objective of the Gateway Program is to evolve into a digital engineering environment and away from the traditional document-based approach for capturing data, reports and baselines.

2.1 APPLICABLE DOCUMENTS

The following documents may include specifications, models, standards, guidelines, handbooks, and other special publications that are called out in sections 3.2 through 3.6. The documents listed in this paragraph are applicable to the extent specified herein. Designations authorized by the Program Manager and established for applicable documents consist of:

• Type 1 documents or standards are those that contain requirements the Program must meet as written.

• Type 2 documents or standards are those that contain requirements the Program can either choose to adopt or accept an alternate proposal.

• Type 3 documents or standards are those that represent the ‘best practices’ observed by or normally used by NASA over the substantial development history of both human and non-human spaceflight missions. The Program does not need to either formally adopt the documents or recommend an alternate.

TABLE 2.1-1 TYPE 1 APPLICABLE DOCUMENTS

Document Number Revision Document Title CSA-GWY-ID-0001 EVR Interface Requirements and Definition Document DSG-SPEC-VSM-003 Gateway Program Subsystem Specification for

Vehicle System Manager (VSM) DSG-SPEC-CDH-004 Gateway Program Subsystem Specification for

Command and Data Handling (CDH) DSG-SPEC-COMM-005 Gateway Program Subsystem Specification for

Communications DSG-SPEC-CS-006 Gateway Program Subsystem Specification for Crew

Systems DSG-SPEC-ECLS-007 Gateway Program Subsystem Specification for

Environmental Control and Life Support System

(ECLSS)

DSG-IRD-EVA-008 Gateway Program Extravehicular Activity (EVA) Compatibility Interface Requirements

DSG-SPEC-GNC-009 Gateway Program Subsystem Specification for Guidance Navigation and Control (GNC)

DSG-SPEC-CHP-010 Gateway Program Subsystem Specification for Crew Health and Performance (CHP)

DSG-SPEC-PWR-011 Gateway Program Subsystem Specification for Power

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DSG-SPEC-IVR-013 Gateway Program Subsystem Specification for Internal Robotics

DSG-SPEC-FSW-014 Gateway Program Subsystem Specification for Software

DSG-SPEC-THR-015 Gateway Program Subsystem Specification for Thermal

DSG-SPEC-MECH-017 Gateway Program Docking System Specification DSG-SPEC-CHI-018 Gateway Program Subsystem Specification for

Computer Human Interface DSG-SPEC-HTCH-019 Gateway Program Subsystem Specification for

Hatches DSG-SPEC-PQS-020 Gateway Program Electrical Power Quality

Specification Requirements for 120Vdc MPCV 70156 F Cross Program Fluid Procurement and Use Control

Specification SLS-SPEC-159 Cross-Program Specification for Natural Environments

(DSNE)

2.2 TECHNICAL AUTHORITY STANDARDS AND REQUIREMENTS

This section identifies the Technical Authority (TA) Standards and Requirements and designations. The NASA Program Manager and TAs are responsible for determining how these standards and requirements are applied depending on the specified type. There are currently no Type 1 TA Standards and Requirements identified.

Type 2 documents are those that contain requirements the Program can either choose to adopt or accept an alternate proposal.

The Element or Module provider will be allowed to propose alternate requirements within documents that they consider to meet or exceed the intent of the Type 2 designation to the Program Manager. Any ‘Applicable’ document listed in a Type 2 document is also considered to be Type 2 unless specified otherwise. The Element or Module will assess equivalency of the requirements and risk to the Program and present the evidence to the NASA TAs and Program Manager for approval. The process for accepting alternates is defined in DSG-PLAN-007, Gateway Systems Engineering Management Plan, Section 5.5.8 Standards.

Type 3 documents are those that represent the ‘best practices’ observed by or normally used by NASA over the substantial development history of both human and non-human spaceflight missions. The Program does not need to either formally adopt the documents or recommend an alternate.

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TABLE 2.2-1 TYPE 2 TECHNICAL AUTHORITY DOCUMENTS

Document Number Revision Document Title

AIAA S-111 2005 Qualification and Quality Requirements for Space Solar Cells

AIAA-S-112 A-2013 Qualification and Quality Requirements for Space Solar Panels

AIAA S-113 A-2016 Criteria for Explosive Systems and Devices on Space and Launch Vehicles

ANSI/AIAA-S-080 A-2018

Space Systems – Metallic Pressure Vessels, Pressurized Structures, and Pressure Components

ANSI/AIAA-S-081 B-2018 Space Systems—Composite Overwrapped Pressure Vessels

ANSI/ESD S20.20

For the Development of an Electrostatic Discharge Control Program for - Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices)

DSG-PLAN-016 Gateway Program Modeling and Simulation Plan DSG-RQMT-002 Gateway Human Systems Requirements

DSG-RQMT-004 Gateway Electromagnetic Environmental Effects (E3) Requirements Document

DSG-RQMT-005 Gateway Structural Design Requirements and Factors of Safety for Spaceflight Hardware.

DSG-RQMT-006 Gateway Loads and Structural Dynamics Requirements for Spaceflight Hardware

DSG-RQMT-007

Gateway Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment Document

DSG-RQMT-008 Gateway Design and Development Requirements for Mechanisms

DSG-RQMT-009 Gateway Requirements for Threaded Fastening Systems in Spaceflight Hardware

DSG-RQMT-011 Gateway Hazard Analysis Requirements

DSG-RQMT-019 Gateway Fracture Control Requirements For Spaceflight Hardware

DSG-RQMT-021 Gateway Requirements for Thin Walled Flexible Pressure Boundary (TWFPB) Hardware Items

GRC-AES-AMPS-

DOC-006 Modular Electronics Standard for Space Power

Systems

GSDO-RQMT-1080 Cross-Program Contamination Control Requirements

IEC 61000-4-2

Electromagnetic Compatibility (EMC) Testing and Measurement Techniques-Electrostatic Discharge Immunity Test for Human Body Model (HBM)

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subassemblies, assemblies and equipment discharge levels

IPC-2220 Series Family of Printed Board Design Documents IPC-6010 Series Family of Printed Board Performance Documents

IPC-CM-770 E Component Mounting Guidelines for Printed Boards

IPC J-STD-001GS G

Space and Military Applications Electronic Hardware Addendum to IPC J-STD-001G Requirements for Soldered Electrical and Electronic Assemblies

IPC J-STD-001G/

Amendment 1

G (10/2017)

Amendment 1 (9/2018)

Requirements for Soldered Electrical and Electronic Assemblies

JSC 20584 Spacecraft Maximum Allowable Concentrations for Airborne Contaminants

JSC 20793 Crewed Space Vehicle Battery Safety Requirements

JSC 62809 Human Rated Spacecraft Pyrotechnic Specification

MIL-STD-981 C + Change 2 (7 August 2015)

Design, Manufacturing and Quality Standards for Custom Electromagnetic Devices for Space Applications

NASA-STD-4003 A + Change 1 Electrical Bonding For NASA Launch Vehicles, Spacecraft, Payloads, And Flight Equipment

NASA-STD-5012 Strength and Life Assessment Requirements For Liquid-Fueled Space Propulsion System Engines

NASA-STD-5018

Strength Design and Verification Criteria for Glass, Ceramics, and Windows in Human Spaceflight Applications

NASA-STD-6001 B Flammability, Offgassing and Compatibility Requirements and Test Procedures

NASA-STD-6016 A Standard Materials and Processes Requirements for Spacecraft

NASA-STD-8719.14 B Process for Limiting Orbital Debris

NASA-STD-I-6030 Standard for Additive Manufactured Spaceflight Hardware for Crewed Vehicles

NPR 8715.6 B

NASA Procedural Requirements for Limiting Orbital Debris and Evaluating the Meteoroid and Orbital Debris Environments

SMC-S-010

Space and Missile Systems Center Standard, Parts, Materials, and Processes Technical Requirements for Space and Launch Vehicles

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TABLE 2.2-2 TYPE 3 TECHNICAL AUTHORITY DOCUMENTS

Document Number Revision Document Title AA AC 20-136B Protection of Aircraft Electrical/Electronic Systems

Against the Indirect Effects of Lightning ACGIH TLVs® and BEIs®

2001 American Conference of Governmental Industrial Hygienists (ACGIH) standard for “Threshold Limit Values (TLVs®) and Biological Exposure Indices (BEIs®),” sections Infrasound and Low-Frequency Sound, Light and Near-Infrared Radiation, and Ultraviolet Radiation

ANSI S12 65-2006 American National Standard for Rating Noise with Respect to Speech Interference

ASME Y14.100 Engineering Drawing Practices ASTM F1192 Guideline for measuring single-event phenomena induced by heavy ions Ionizing Radiation Displacement Damage references

"Proton Effects and Test issues for Satellite Designers:

Displacement Effects”, 1999 NSREC Short Course

IPC-2152 Standard for Determining Current Carrying Capacity in Printed circuit Board Design

ITU P.863 Perceptual Objective Listening Quality Assessment JEDEC JESD57 Test Procedures for the Measurement of SEE in

Semiconductor Devices from Heavy-Ion Irradiation JSC 22538 Flight Crew Health Stabilization Program JSC 26895 Guidelines for Assessing the Toxic Hazard of

Spacecraft Chemicals and Test Materials JSC 63414 Spacecraft Water Exposure Guidelines (SWEG) JSC 63555 Nutrition requirements, Standards, and Operating

Bands for Exploration Missions JSC 63557 Net Habitable Volume Verification Method JSC-HDBK-07-0001 High Energy/LET Radiation EEE Parts Certification

Handbook JSC JPR 8080.5, E22 JSC Design and Procedural Standards MIL-STD-130 Department of Defense Standard Practice, Identification Marking of U.S. Military Property MIL-STD-883 Microcircuits TM 1017: Neutron irradiation

TM 1019: Ionizing radiation (total dose) test procedure MIL-STD-1474 E Department of Defense Design Criteria Standard, Noise Limits MSFC-STD-3716 Standard for Additively Manufactured Spaceflight

Hardware by Laser Powder Bed Fusion in Metals MSFC-SPEC-3717 Specification for Control and qualification of Laser

Powder Bed Fusion Metallurgical Process NASA/SP-2010-3407 Human Integration Design Handbook NASA/SP-2015-3709 Human Systems Integration (HSI) Practitioner’s Guide

NASA/TM-2015-

218564

Minimum Acceptable Net Habitable Volume for Long- Duration Exploration Missions

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NASA/TP-2014-

218556

Human Interface Design Process

NPD 8900.5 B NASA Health and Medical Policy for Human Space Exploration

SAE ARP 5414A Aircraft Lightning Zoning SAE ARP 5577 Aircraft Lightning Direct Effects Certification SAE ARP 5412B Aircraft Lightning Environment and Related Test

Waveforms SAE EIA-649B Configuration Management Standard

2.3 REFERENCE DOCUMENTS

The following documents contain supplemental information to guide the user in the application of this document. These may be called out in section 3.2 rationale or other areas of the document.

Document Number Document Revision Document Title

DSG-DDD-002 Gateway Mission Design Document DSG-GRA-004 Cross Program Groundrules and Assumptions (GR&As) for

Analysis and Development DSG-PLAN-002 Gateway Margin Plan DSG-PLAN-XXX The Gateway Program Subsystem Specification for Command and

Handling TTE Network DSG-RQMT-004 Gateway Electromagnetic Environmental Effects (E3)

Requirements Document DSG-RQMT-007 Gateway Requirements for the Control of Electromagnetic

Interference Characteristics of Subsystems and Equipment Document

HEOMD-004 Human Exploration Requirements

IEST-STD-

CC1246E

E Product Cleanliness Levels - Applications, Requirements, and Determination

Rec. ITU-R RA.479-

Protection of Frequencies for Radioastronomical Measurements in the Shielded Zone of the Moon

NASA-STD-3001 NASA Space Flight Human-System Standard

NASA TM-2009-

214785

Handbook for Designing Micrometeoroid and Orbital Debris (MMOD) Protection

NASA TM-2015-

218214

NASA Meteoroid Engineering Model Release 2.0

NASA TM-2015-

218592

NASA Orbital Debris Engineering Model

NASA TP-2015-

219290

NASA Orbital Debris Engineering Model (ORDEM) 3.0 - Verification and Validation

NASA TM-2017-

219290

Interpolation of NASA-STD-3001 Levels of Care for Exploration Medical System Development

NASA STD-8729.1A Maintainability Objective 4.A.2.D

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NPR 8705.2C Human-Rating Requirements for Space Systems SN-C-0005 Space Shuttle: Contamination Control Requirements SSP 30426 Space Station External Contamination Control Requirements SSP 30573 Space Station Fluid Procurement and Use Control Specification V2 6009 DCS Treatment Capability V2 1103 LEA Suited DCS Prevention Capability

2.4 ORDER OF PRECEDENCE

In the event of a conflict between the text of this specification and the references cited herein, the text of this specification takes precedence. Nothing in this specification, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

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3.0 DESCRIPTION AND REQUIREMENTS

3.1 SYSTEM DESCRIPTIONS AND DESIGN CONSIDERATIONS

The purpose of the Gateway is to fulfill NASA's Human Exploration and Operations Exploration Objectives for Cislunar Demonstration of Exploration Systems, as described in HEOMD-

001. These objectives are part of the NASA implementation of Space Policy Directive 1:

SPD-1: Reinvigorating America's Human Space Exploration Program:

"Lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system and to bring back to Earth new knowledge and opportunities.

Beginning with missions beyond low-Earth orbit, the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations."

The Gateway is a reusable and sustainable command center in Lunar orbit, providing a safe location for crew transition to a lunar landing vehicle after checkout. The Gateway also provides a location for deep space human and systems testing as a stepping stone to Mars exploration.

Mission phasing has been implemented to characterize which requirements are critical to enable Boots-On-The-Moon in 2024.

Phase 1 – Initial complement of modules needed to support BOTM 2024, Power Propulsion Element, Minimum Habitation Capability & Logistics Module.

Phase 2 – Remaining elements of the architecture to support longer duration missions and greater utilization capability, International Habitat, US-Habitat, Airlock and Extravehicular Robotics.

3.1.1 System Definition

The Gateway is comprised of the following modules:

a. Power and Propulsion Element (PPE)

b. Minimum Habitation Capability (MHC)

c. Habitation Modules (HABs)

d. Logistics Modules (LM)

e. Extravehicular Robotics (EVR)

f. Airlock

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3.1.2 System Description

The Gateway is a lunar orbiting facility, which is supported with consumables, maintenance items, and experiments. The Orion spacecraft will bring crews to the Gateway and return them to Earth once the mission is completed. The Gateway will employ radio-frequency (RF) links with Earth based networks for audio, video, data, and command communications. The Gateway functional breakdown is described below.

3.1.2.1 Power and Propulsion Element

The PPE provides the capability to generate power for the Gateway, transport Gateway between cis-lunar 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 also provides accommodations for external utilization.

3.1.2.2 Minimum Habitation Capability

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

3.1.2.3 Extravehicular Robotics (Phase 2)

The EVR provides the capability to deploy and retrieve external utilization payloads, utilize the science airlock to retrieve/deploy payloads, deploy free-flying payloads, inspect the Gateway system, capture and berth/unberth of robotic spacecraft, berth and unberth modules to support assembly and reconfiguration if needed, support lunar and planetary missions by assembling spacecraft and transferring equipment, perform scheduled and contingency maintenance including by transferring ORUs to the interior via the science airlock, support self-maintenance of robotic components and support EVA crewmembers.

The EVR nominally performs its tasks autonomously so that it can operate any time that it is required, without crew presence, without a guaranteed ground downlink and without real-time ground supervision.

The EVR 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 External Robotics will have the capability to translate along the Gateway infrastructure, by walking to grapple fixtures placed externally along the Gateway modules.

3.1.2.4 International Habitat (Phase 2)

The HABs 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 MHC and two HABs. The Gateway will have two HAB modules: an International HAB (I-HAB) and a U.S. HAB (US-HAB). Each HAB

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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), IVR and EVR command and control system) to be accomplished using LMs.

I-HAB will be the habitation element provided by the International Partners. Allocations of the habitability functions between the pressurized volumes will be adjusted as the architecture matures.

3.1.2.5 United States Habitat (Phase 2)

The US-HAB will be the U.S.-provided habitation element that, together with the I-HAB, provides the primary habitability functions for the Gateway.

3.1.2.6 Airlock (Phase 2)

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

3.1.2.7 Logistics Module

The 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. When provided as a commercial resupply service, LM's are expected to be fully independent spacecraft with their own propulsion, power, thermal control, GN&C, and communications systems during undocked mission phases. When docked at Gateway, LMs extend specific Gateway functions to support crew systems, integration with the Gateway command and control systems, communication, and habitation, but still retain some independence for power generation, thermal control, and spacecraft systems management.

3.1.2.8 Visiting Vehicle

Potential visiting vehicles, other than LM, are being defined at this time but could conceivably include robotic and human lunar landers (HLLs) as well as crewed vehicles built by NASA and International Partners.

3.1.2.9 Human Lander System

TBD

3.1.3 Human Rating Certification

The NASA Procedural Requirements (NPR) 8705.2C, Human-Rating Requirements for Space Systems, defines the requirements, standards and certification package contents that will be used to certify crewed deep space systems, and provides guidance for Gateway to achieve

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Human Rating compliance. The requirements contained within the NPR prescribe that a human-rated system accommodates human needs, effectively utilizes human capabilities, controls hazards with sufficient certainty to be considered safe for human operations, and provides, to the maximum extent practical, the capability to safely recover the crew from hazardous situations. Formal Human Rating certification will be obtained for each integrated architecture/mission (including Gateway Modules and the docked crewed vehicle) prior to each crewed flight. Per the NPR: “Each independent element is not required to obtain a Human- Rating Certification – the certification is for the entire crewed space system.” The Human Rating Certification Package (HRCP) is the documentation of compliance/evidence for the NPR 8705.2C. Also included in the HRCP is the development of future mission-specific annexes that outline human rating progress and compliance that will occur at various stages of maturation as the Gateway is assembled (content in the annexes will not be part of the endorsed/certified package; it is informational only). Lastly, the HRCP will include the NPR requirements trace and applicability matrix, by mission. The status of the HRCP will be provided at key Gateway milestones with its content and format evolving along the way. Deliverable expectations (for the HRCP as well as those products owed to the HRCP by Programs and Elements) will be provided along with progress of each deliverable. The actual HRCP document will not be complete and ready for endorsement until all compliance evidence expected for assessment is received.

3.1.4 Design Considerations

This section provides general design considerations and descriptions for the Gateway. The content contained within this section is not formally verified, but in many cases it is complementary to and influenced by verifiable requirements found in Section 3.2 of this document, and other Level 2 requirements. The considerations are derived from the unique mission of the Gateway and the unique natural and induced environments the Gateway will experience. Adherence to these considerations and ground rules are important to ensure the Gateway can perform the intended mission and endure the expected lifetime while providing a habitable productive environment for the crew. In the case of any apparent conflicts between content in Section 3.1 and requirements housed in Section 3.2 or other requirements documents, requirements shall supersede Section 3.1 content.

3.1.4.1 Modules

Each Gateway module should be capable of storing power, receiving/distributing power, controlling temperature, and providing Command and Data Handling (C&DH) independent of other elements. Gateway should have a system architecture that allows sharing of resources (to include power, thermal control, C&DH, and Environmental Control and Life Support (ECLS) for pressurized modules) across module interfaces.

Rationale: The Gateway will be assembled in cis-lunar space at a planned cadence of one flight per year. Therefore, each Module should be as self-contained as practical and each on-orbit stage must result in a sustainable spacecraft. In addition, power storage and temperature control will be needed by the module from launch to activation to keep the module within allowable temperature limits. The purpose of independence and sharing resources provides the capability to respond to real time on-orbit anomalies and failures. Independence may be needed to protect crew and recover the spacecraft in the event of a loss of pressure in an adjacent

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module. Sharing of resources may be needed to recover from a loss or diminished resources in one module being supplied from an adjacent module.

3.1.4.2 Gateway Station Assembly

Gateway modules should be designed to be assembled primarily by automated docking with automated deployable mechanisms. External robotics will be used for external payload installation and removal.

Rationale: Initial assembly missions may not have crew available to support assembly tasks while external robotics capability is also not expected to be available for early missions. EVA capability is reserved for contingency maintenance and will not be available until late in the assembly timeframe.

3.1.4.3 Communications Line-of-Sight

The Gateway should be designed with the –Z surface clear of structure, including planned Visiting Vehicles (VV), to avoid communication blockage.

Rationale: Based on the initial Gateway reference architecture, the planned Near-Rectilinear Halo Orbit (NRHO), and the planned Solar Pressure Equilibrium Attitude (SPEA), the –Z surface of the Gateway is the optimal location for High Gain Antennas to support lunar and Earth communications. This assumes the –Z axis is nominally directed towards ecliptic north. Placing additional primary structure or secondary structure on the existing configuration could result in structural blockage of the communication line-of-sight. Refer to coordinate system in the figure below. The origin is located at the center of the PPE forward docking interface at the center of the docking mechanism Hard Capture Surface (HCS).

3.1.4.4 Thermal Flight Attitude Independence

Active and Passive thermal systems should be designed with enough robustness and capacity to allow Gateway to fly in attitudes that are driven/support operations for extended periods.

Rationale: To maximize the Gateway's flexibility to support visiting vehicles, maintain Earth to Lunar communication coverage and minimize propellant demand the Gateway thermal system

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should be attitude independent. This is achievable using body mounted radiators if there is enough surface area for the required radiators. Radiators are most effective in rejecting heat when pointed towards deep space because they are not subjected to the heat radiated from the Moon or Earth. In the NRHO at the SPEA orientation, the surface area of Gateway that is facing deep space and the surface area facing radiation from the Moon and/or Earth changes over time. Therefore, to meet the thermal attitude independence, the Gateway will need radiators on each face of the external surface. Window(s) and secondary structure for other systems, such as Low Profile Grapple Fixtures (LPGFs), Small Orbital Replacement Unit (ORU) Interfaces (SORIs), EVA translation aids, GNC sensors, batteries, propellant lines, etc. will all likely have location constraints. In determining the location of external secondary structure, preservation of surface area for thermal radiators should be considered.

3.1.4.5 Autonomy

Gateway should be designed to accommodate autonomy (as implemented by Vehicle System Manager (VSM), Intravehicular Robotics (IVR) and Extravehicular Robotics (EVR) systems) to the greatest extent practical.

Rationale: The Gateway will operate in cis-lunar space with infrequent, short periods of on-orbit crew. The Gateway has a requirement to sustain a period of uncrewed operations for three years and then return to a state ready for resumed crew operations. EVR, IVR, and VSM will provide unique capabilities that provide reduced Earth reliance for future missions. EVR and IVR services can be utilized during all phases (crewed, non-crewed) and will support operations, maintenance, and utilization. Gateway will largely be an uncrewed vehicle, making robotics essential systems for utilization.

3.1.4.6 Dust Mitigation Strategy

The Gateway design should be resilient to contamination from lunar regolith.

Rationale: The Gateway dust mitigation strategy will be to limit dust from arriving at Gateway by placing constraints on lunar excursion vehicles. However, it is anticipated that dust cannot be completely eliminated, so Gateway should protect for meeting performance requirements when exposed to lunar dust. As the lunar enterprise campaign continues, the Gateway Program will develop quantitative requirements for the expected induced environment on Gateway and corollary requirements to levy on visiting vehicles to constrain the amount of dust that enters the Gateway environment. At that time, this design consideration will be replaced with quantitative requirements.

3.1.4.7 Internal Architecture

Internal Architecture is the methodology and design for outfitting a habitable volume to accommodate systems and humans while meeting mission objectives.

A consistent, well-planned architecture will maximize volume efficiency, enable and enhance crew health and performance, and promote the extensibility of the spacecraft to meet future capabilities and mission requirements.

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A successful approach will employ commonality in orientation across pressurized elements, lighting techniques that enhance the living space, and clear and unencumbered translation paths to optimize movement.

The architecture must provide solutions for securing equipment and stowage, so that crew can interact with it. These solutions should anticipate reconfiguration and growth and provide a development strategy that protects the quality of the architecture as the space evolves. For example, a crew workstation may be initially hosted in I-HAB and might be moved at a later stage or supplemented by additional workstations in US-Hab.

3.1.4.8 Habitability

Habitability is the extent to which a space is suitable for human life and it should be a prime consideration in the design of all vehicles, habitats, and hardware used by a crew. Habitable volumes will provide an atmosphere for the crew for all nominal missions.

3.1.4.9 Function Allocation

Functional allocation is the distribution of tasks, capabilities, and volumes within a habitable element or set of habitable elements. This distribution drives the flow of traffic, which can dramatically affect the architecture. Complimentary tasks should be co-located and antagonistic tasks should be separated. Functional areas should be separated for tasks that could degrade emergency response or safety, or that produce environmental conditions detrimental to mission performance or habitability (for example, glare, noise, vibrations, heat, odors, etc.). The relationship between tasks should be examined with respect to suitable compatibility, cleanliness, visual and auditory privacy, resource needs, and translation.

3.1.4.10 Orientation

Gateway should establish a human-based frame of reference across the entire vehicle that enables the crew and ground to identify and communicate about locations within the system at any given time.

3.1.4.11 Living Space

The internal living space should provide adequate habitable volume to perform the expected functions and to translate through the space. A clear, unencumbered translation path should be defined and maintained to facilitate the performance of mission tasks. Working and living spaces intended for crew occupancy should be intuitive and aesthetically pleasing to facilitate human productivity and mission productivity.

Colors, textures and lighting provisions should be chosen to support the functions intended for each working or living space, and, when used to provide visual orientation cues, should be capable of consistent throughout all habitable areas.

3.1.4.12 Internal Lighting and Acoustics

Lighting is an essential element of architecture that should be leveraged to help crew use the space. It should be designed to complement the architecture. It should also be designed to

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promote crew health and performance through circadian cycling, proper task lighting, and a high degree of controllability.

Acoustics should be managed to reduce hearing problems or annoyance, minimize unnecessary disruption to crew work and habitation functions, not inhibit speech communications, and ensure the detection and appropriate conveyance of urgency of auditory cautions, warnings, and alerts.

3.1.4.13 Outfitting

Outfitting refers to hardware and soft goods installed in the pressurized elements. All mechanical systems outfitted for launch should be accessible and maintainable by the crew.

The need for secondary structure should be minimized in order to reduce element mass.

The outfitting approach should be modular to accommodate reconfiguration and interoperability between elements, and it should be extensible to accommodate growth in equipment, systems, and stowage. Growth, including the addition of stowage and outfitting, should not compromise the clear and unencumbered translation path and living space. Spacecraft scalability should consider non-obstructive cable/hose routing so as to maintain translation paths that are free of entrapment (tangles, snags, catches, etc.).

The design of the interior should have features that manage the addition of equipment cables and hoses without intruding on the living and translation space.

For hardware that can restrain or restrict the crew, that hardware should allow for quick (guideline of 30 seconds) and sufficient crew egress from that apparatus such that the crewmember can don an emergency breathing apparatus and/or an emergency entry suit if required.

All outfitting required to be installed on orbit, removed for return or disposal, or transferred between elements should be designed to fit through the smallest corridor.

Payload and stowage mounting and resource interfaces should be standardized across all elements allocated those functions.

3.1.4.14 Window

TBD

3.1.4.15 Radiation Protection

Radiation exposure should be mitigated by vehicle design and operational approaches. During radiation events, if thresholds are reached, crewmembers would seek shelter in higher shielded locations of Gateway in order to minimize exposure. Design considerations should be given to providing the radiation safe haven protection as part of the habitable volume, ideally as part of the crew quarters location.

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3.1.4.16 Supportability and Maintainability

The Gateway should include supportability and maintainability as part of the system's design characteristics. Designing for supportability and maintainability assists in ensuring system life-cycle availability and affordability. To assist with supportability, Gateway should strive for highly reliable systems to minimize maintenance. When external maintenance is required, the Gateway strategy is to use robotic capability first, while crewed and uncrewed, and use contingency EVA capability as a backup. The Gateway should have modular hardware designs that reduce hardware to smallest replaceable unit and utilizes common component/system interfaces that allow items to be interchangeable between modules/elements. Modularity requirements early in design will pay off in life cycle by reducing resupply weight and enabling commonality across modules at the lowest level practical in each system. Interchangeable elements will minimize the number of unique spares required.

The Gateway should be maintainable and reconfigurable on-orbit using a minimum set of tools and fasteners that are as common as feasible with the other systems. It is understood that exploration missions beyond LEO will be particularly mass and volume limited. There will not be the ability to provide a tool kit that consists of over 500 unique tools like on the ISS.

Additionally, common tools reduce the training and support requirements for the system. For those reason, providers of spacecraft, spacesuits, EVA tools, scientific payloads, IVR and other hardware will need to design their hardware to be maintained by a smaller set of common tools. Under this Common Tools umbrella are two parts: the IVA Tools and EVA Tools. There would be an IVA Tool Kit with a limited set of tools to perform maintenance on any hardware inside the habitable volume and will drive IVR end effectors. This includes maintenance of the spacesuit, EVA Tools, payloads, replacing spares, hatch operations or anything else that is stowed or brought into the habitable volume. There would also be a limited set of EVA Tools designated to be used for maintenance on any hardware outside of the habitable volume, such as an external antenna, solar arrays, a rover, or an external science payload.

As a goal, Gateways should design all components and assemblies to utilize the Common Tools and Fasteners lists identified in the DSG-SPEC-CS-006, Gateway Program Subsystem Specification for Crew Systems for IVA tools/fasteners and the DSG-IRD-EVA-008, Gateway Program EVA Compatibility IRD for EVA tools/fasteners, though it is understood that it will not be practical 100% of the time. However, the intent of this requirement is that all planned maintenance and contingency tasks must be carried out using this Common Tools Kit. Any designs that create the need for an additional tool outside of this set of tools should be routed through the appropriate Program Control Boards for approval.

3.1.4.17 Upgradeability

The Gateway should provide for upgradeability which should allow technology infusion as well as address obsolescence issues. Upgradeability will be necessary in the future to support exploration needs such as Lunar and Mars exploration activities. Upgrades should be considered through initial and follow-on phases of the program and include commonality to identify and recommend potential supportability enhancements such as identical interfaces, interchangeable parts, common tools, and interoperable items that can be used in different modules.

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3.1.4.18 System Operational Availability

The Gateway should establish operational availability consistent with mission objectives.

Operational availability (Ao) is achieved by implementing highly reliable systems and incorporating common and modular hardware designs that consider ease of maintenance. For Gateway, there will be times when operational availability is required to be at the highest possible level for manned operations (for example, to support surface operations) and perhaps to a lesser degree for unmanned operations.

Note: Operational availability (Ao) typically relies on allocation of hardware reliability for inherent availability (Ai), reliability centered maintenance (RCM) (or preventative maintenance) for achieved availability (Aa), and the logistics/maintenance support infrastructure to achieve the designated requirement for Ao. Additional detail is captured in the Gateway Integrated Logistics Support Plan (ILSP), DSG-PLAN-020.

3.1.5 Gateway Functional Diagram

3.1.6 Interface Description

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3.2 REQUIREMENTS

3.2.1 Design Constraints

L2-GW-0161 Launch Vehicle Capability

The Gateway shall be capable of launching modules on a commercial launch vehicle or as a Co-manifested Payloads (CPL) on the Space Launch System (SLS).

Rationale: Having a commercial launch vehicle & SLS, keeps trade space open for a robust assembly sequence, and protects for development issues with co-manifesting, extended flight suspension of SLS or Orion, etc. SLS CPLs are available beginning with Block 1B. The Gateway modules will be launched to assemble the Gateway in Cis-Lunar Space.

L2-GW-0166 Gateway Standard Docking Port

The Gateway shall use docking systems compliant with the DSG-SPEC-MECH-017 Gateway Program Docking System Specification.

Rationale: All docking ports shall utilize common design to support interoperability.

L2-GW-0160 Gateway Docking Ports

The Gateway shall have a minimum of four Gateway Docking System compliant docking ports available for non-permanent use in any combination of radial or axial configurations.

Rationale: Accommodations include allocation of ports to the PPE and to support habitation, logistics resupply, airlock capability, extensibility options, and crewed vehicle contingency docking. These modules will deliver supplies and utilization systems to the Gateway, as well as the capability to resupply, refuel, and dispose of trash. Pressurized and unpressurized logistics should be accommodated. It could also include docking of a HLL or additional HABs providing communications, thermal, power, orbit maintenance and attitude control. As required, assessments will be performed for each new module. Implementation of the DSG-SPEC-MECH-017, Gateway Docking System Interface Definition Document will ensure interoperability of docking systems for all modules regardless of module provider.

L2-GW-0164 Solar Electric Propulsion (SEP)

The Gateway shall use SEP.

Rationale: A SEP system that is extensible to future human deep space exploration missions will be demonstrated on the Gateway.

3.2.2 Mission Design

L2-GW-0163 NRHO Orbit

The Gateway shall be placed and operate in a NRHO.

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Rationale: Orbit trade studies, cited in DSG-DDD-002 Gateway Mission Design Document (MDD), identified a Near-Rectilinear Halo Orbit (NRHO) as optimal for minimal energy orbit maintenance, and accessibility to multiple deep space destinations. Specifically, an L2 orbit in a 9:2 resonance with the lunar synodic period with apolune over the South Pole was selected for extended lunar communications with surface assets at the South Pole. The NRHO is described in detail in the MDD.

L2-GW-0029 Single Orbit Transfer

The Gateway shall be capable of performing a single round trip transfer to Distant Retrograde Orbit (DRO) and back within 11 months.

Rationale: A series of robust uncrewed capabilities, in diverse cis-lunar orbits, will reduce risk, maximize closure of knowledge gaps, and prepare for operations beyond the Earth- Moon system. 11 months includes transit time plus stay at destination orbit and supports a yearly crew mission of at least 30 days. The transfer is assumed to occur with a fully-constructed stack, not including logistics modules, crew visiting vehicles, or lander elements (IAC-3 configuration 14). The targeted DRO will remain stable for 3 months for cislunar transfer applications. The DRO will remain stable for 100 years for Gateway End-of-Life applications.

L2-GW-0026 Propulsion System Capability

The Gateway shall…