LCRNS SRD.pdf

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05/17/2022

Jaime Esper Date Project Manager, LCRNS NASA Goddard Space Flight Center iii

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Preface

This is the NASA LCRNS Lunar Relay Service Requirements Document.

This document is controlled by the LCRNS Project Configuration Control Board (CCB). This document will be updated by Documentation Change Notice (DCN) or complete revision.

An uncontrolled copy of this document may be downloaded from the NASA LCRNS Web Page at: Lunar Communications Relay and Navigation Systems | ESC Public Site (nasa.gov) v

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Table of Contents

Section 1. Introduction

1.1 Threshold Relay Capabilities by Phase (IOC)

1.2 Document Convention and Notation

1.3 Configuration Control

Section 2. Documentation

2.1 Applicable Documents

2.2 Reference Documents

Section 3. Lunar Relay Service Requirements

3.1 Lunar Relay Service Functional Requirements

3.2 Service Performance Requirements

3.2.1 Communications Requirements

3.2.2 Space Internetworking Data Service Requirements

3.2.3 Position, Navigation, and Timing (PNT) Services

3.2.4 Lunar Search and Rescue (LunarSAR) Services

3.2.5 Lunar Relay Service On-orbit Validation Capabilities

3.2.6 Lunar Relay Cybersecurity

Appendix A. SRD Requirements Summary

Appendix B. User Mission Specific Information and Timeline Reference

3.3 User- Level Assumptions

3.3.1 Communications System Characteristics

3.3.2 PNT System Characteristics

3.3.3 User Timelines

3.3.4 Reference Trajectories for Descent and Ascent

Appendix C. LunaNet Interoperability Compliance Matrix

Appendix D. Glossary and Acronym List vi

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List of Figures

Figure B-1 NASA Reference Trajectory for HLS Landing Figure B-2 NASA Reference Trajectory for HLS Departure

List of Tables

Table 2-1 Applicable Documents Table 2-2 Reference Documents Table 3-1 Lunar Relay Frequency Band Requirements Table 3-2 Lunar Relay Real-Time Data Rate Recommendations Table 3-3 Artemis Data Rate Service Requirements Table 3-4 Artemis Data Volume Service Requirements Table 3-5 Aggregate Artemis Data Rate Service Requirements Table 3-6 Aggregate Artemis Data Volume Service Requirements Table 3-7 Representative User Scenario PNT Performance Reqs. - IOC Table 3-8 Representative User Scenario PNT Performance Reqs. - EOC Table 3-9 Service Lunar Orbit and Time Requirements Table 3-10 Lunar Relay PNT Reference Signal Source Requirements Table A-1 Requirements Summary Table Table B-1 User System Performance Table B-2 Artemis III Table B-3 Artemis IV Table B-4 Artemis V Table B-5 Non-Crewed Artemis mission estimated support Table C-1 Interoperability Specification Compliance Matrix for IOC

ESC-LCRNS-REQ-0090.

Section 1. Introduction

The NASA Lunar Communications Relay and Navigation Systems (LCRNS) Project has defined a set of requirements for Lunar Orbiting Relay Services by LunaNet Service Providers (LNSP) to support Artemis missions and assets (Human Landing System, Orion, Lunar Terrain Vehicle, Extravehicular Activities, etc.), NASA payloads utilizing the Commercial Lunar Payload Services (CLPS) program, and other NASA science and technology missions in the lunar regime. The service is expected to initially include a few relays in lunar orbit in what is referred as the Initial Operating Capability (IOC) covering the 2024 through 2027 timeframe. A more complex network will grow to meet expanding needs during the Enhanced Operating Capability (EOC), starting in 2028 and beyond.

This Lunar Relay Services Requirements Document (SRD) covers end-to-end communication and navigation services from users in the lunar proximity to Earth and from Earth to lunar users via relay links. In addition, it covers lunar users communicating and navigating within the lunar proximity independent of Earth. Key interface requirements to NASA reference lunar vehicles (i.e., HLS, CLPS, etc.) are included in this document as well as interfaces between the flight and ground systems for scheduling, command and telemetry, and earth station compatibility. The companion and applicable LunaNet Interoperability Specification (LN-IS Baseline V.0200) provides a specific set of Interoperability Specifications (appendix C) that must be met by all operators. It is expected this document will evolve over the next year as element designs and concepts of operation mature.

1.1 Threshold Relay Capabilities by Phase (IOC)

IOC capabilities form the set of threshold requirements that shall be met by a LNSP. EOC capabilities can be implemented initially but are not part of the threshold set. Other NASA documentation may refer to the IOC capability as “sortie,” and the EOC capability as “Artemis Base Camp (ABC).”

1.2 Document Convention and Notation

This document uses the term service for all exchange of data with the user mission platform, as well as information derived from the data exchange and radio signals received from celestial objects (for PNT services). This term is inclusive of all transmit, receive, radiometric, science and calibration services. The lunar relay does not perform telemetry and command processing functions for the purpose of controlling users, only providing a data pass-through. Data rates are given as the bit rate after framing. Any additional rate capability needed to accommodate encoding or modulation must be accounted for.

Due to the potential operational scenario of having multiple crewed in-space command centers, such as inhabited lunar orbiting stations and inhabited surface stations, the general terms of forward and return are defined based on end users and the point of origin of the starting transmission. For example, forward could refer to the signal sent from a crewed lander on the lunar surface (starting transmission) to a station in lunar orbit, and return would be the opposite. Likewise, forward could refer to the data transfer from a user on Earth (starting transmission), to a user in Lunar space, and return would be the opposite. In addition, Direct-to-Earth or DTE refers to the geometric line-of-sight visibility of relays or users in the lunar vicinity, and not to a directional (“to”) reference. Hence, DTE communications can refer to a transmission originating from the lunar vicinity, as well as a transmission originating from Earth. Directionality is qualified by the forward or return link nomenclature.

Hence for a transmission originating on Earth, a forward DTE link can be established with a user in lunar space. Proximity links are used to refer to user-relay, or user-user links in the lunar vicinity, whether forward or return. Finally, cross-links are used for communications between relays.

A requirement is preceded by a shall. This document follows the formatting style of the document template defined by the SCaN Program Configuration Management Office. In some cases, the values of quantities included in this document are not certain and are designated as to be reviewed (TBR), to be determined (TBD), or to be supplied (TBS). Where approximate values of such quantities are known and provide useful guides for development, these are shown along with the TBR notation.

Where no value is yet known, a TBD is included. Where a value is known but has not been supplied to the SRD book manager, a TBS is included. Appendix C (TBR) includes a summary of the TBRs, TBDs, and TBSs noted in this document.

1.3 Configuration Control

Changes to this requirements document shall be controlled using procedures set forth in the NASA LCRNS Configuration Control Board documentation.

Section 3. Lunar Relay Service Requirements

3.1 Lunar Relay Service Functional Requirements

LCRNS.3.0010 Interoperability The Lunar Relay service shall comply with the interfaces specified in the LunaNet Interoperability Specification LN-IS Baseline V.2 per the compliance matrix in Appendix C.

Rationale: Lunar relay nodes function within the LunaNet architecture, which specifies a set of standard interfaces enabling interoperability between systems including operation between lunar and earth elements that contribute to the network. Appendix C provides the compliance matrix for the subset of requirements within this specification for each phase of missions.

Phase: IOC, EOC

LCRNS.3.0020 Lunar Relay Communications Function The Lunar Relay Service shall provide key operational support to lunar systems.

Rationale: Providing key operational support implies the existence of a robust design, including failure tolerance or functional redundancies as well as high-quality design standards. Lunar systems include HLS, EVA, LTV, Habitat, ISRU, Robotic Systems.

Phase: IOC, EOC

LCRNS.3.0030 Lunar Relay Ubiquitous Signal for Position, Navigation, and Timing and Broadcast Messaging Service The Lunar Relay service shall provide Augmented Forward Signals (AFS) with broadcast messaging.

Rationale: This signal will enable users’ in-situ autonomous lunar orbiting and surface asset navigation, time knowledge, and situational awareness to meet their mission requirements. Crewed, uncrewed, and robotic assets in the lunar space volume region and on the lunar surface need to navigate and have lunar-centric situational awareness independent of Earth-assets (e.g., DSN, NSN, Commercial Stations). The lunar relay provision of signals structured to provide pseudorange, Doppler, and time transfer, with associated message content, enables a lunar-relative and inertially-tied navigation/positioning/time solution to meet their operational requirements for PNT, network knowledge, and alerts. Drivers for PNT accuracy and timeliness include HLS landing accuracy, EVA, and surface mobility asset(s) position knowledge, ISRU for science-related needs and geographic location, and utilization payload positioning.

Phase: IOC, EOC

LCRNS.3.0040 Lunar Relay Position Navigation and Timing Function The Lunar Relay service shall provide functionality via dedicated service for in-situ autonomous lunar orbiting and surface asset navigation and time knowledge.

Rationale: Users unable to benefit from the functionality described in LCRNS.3.0030, require PNT services provided via dedicated links. Crewed, uncrewed, and robotic assets in the lunar space volume region and on the lunar surface need to navigate independent of Earth-assets (e.g., DSN, NSN). The lunar relay provision of signals structured to provide pseudorange, Doppler, and time transfer, with associated message content, enables a lunar-relative and inertially-tied navigation / positioning / time solution to meet their operational requirements.

Drivers for PNT accuracy and timeliness include HLS landing accuracy, EVA, and surface mobility asset(s) position knowledge, ISRU for science-related needs and geographic location, and utilization payload positioning as listed in section 3.2.3.

Phase: IOC, EOC

LCRNS.3.0050 Lunar Relay Real-time Functionality The Lunar Relay Service shall provide a lunar communications relay capable of real-time data relay services between Earth and Lunar Users.

Rationale: The lunar communications network is a critical piece to enable mission execution during all mission phases. This requirement defines the capability required to support the initial crewed missions to the lunar surface. Realtime is defined as data flow through the relay with the minimum latency achievable. This service requires all links between the sender and the receiver to be available.

Phase: IOC, EOC

LCRNS.3.0060 Lunar Relay Non-Real-Time Functionality The Lunar Relay Service shall provide a lunar communications relay capable of store-and-forward data relay services between Earth and Lunar Users.

Rationale: A store-and-forward capability is needed to increase the amount of data that the network can return to Earth and allows coverage of far-side assets when orbital mechanics preclude direct contact with Earth.

Phase: IOC, EOC

LCRNS.3.0070 Relay between Lunar Users (Real-Time) The Lunar Relay Service shall provide a lunar communications relay capable of real-time data relay services between Lunar Users.

Rationale: Communication and commanding between lunar platforms without routing to Earth will be necessary to execute a sustained lunar presence.

Phase: EOC

LCRNS.3.0080 Relay between Lunar Users (Non-Real-Time) The Lunar Relay service shall provide a lunar communications relay capable of store-and-forward data relay services between Lunar Users.

Rationale: Communication and commanding between lunar platforms without routing to Earth will be necessary to execute a sustained lunar presence.

Phase: EOC

LCRNS.3.0090 Communications Relay Network Availability The Lunar Relay Service shall achieve an inherent availability of at least 95% normal, 98% critical ops for data and PNT services to/from lunar proximity.

Rationale: The lunar communications network is a critical piece to enable mission execution during all mission phases. To rely on these communications for critical mission events, the service capability needs to be available/reliable to the greatest extent possible. Inherent availability (Ai) is defined as availability of a system with respect only to operating time and corrective maintenance. It can be calculated as Ai = MTBF ÷ (MTBF + MTTR). Critical mission events are normally associated with dynamic events, including maneuvers, or human operational activities identified as such. MTBF=Mean Time Between Failure. MTTR= Mean Time to Recover.

Proficiency based on SCAN SRD/PCA requirements.

Phase: IOC, EOC

LCRNS.3.0100 High-rate Data Services Relay Network Coverage The Lunar Relay Service shall provide high data rate communications coverage to/from the lunar south pole (80° - 90° South) of at least 75% of every Earth day (TBR) at IOC, and 90% of every Earth day at EOC (TBR).

Rationale: The high-rate data service requires Ka links, driving cost and schedule to implement. All Artemis landing sites considered are within 80-90deg south latitude.

Phase: IOC, EOC

LCRNS.3.0110 General Relay Network Coverage The Lunar Relay Service shall provide dedicated link low data rate coverage to/from the lunar south pole (80° - 90° South) of at least 90% of every Earth day.

Rationale: Health and status and PNT services can be met with more available and mature S and X systems. Availability of these services can be increased without undue burden on the development effort.

Phase: IOC, EOC

LCRNS.3.0115 Dedicated PNT Services Coverage The Lunar Relay Service shall provide dedicated PNT services coverage to/from the lunar south pole (80° - 90° South) of at least 98% (TBR) of every Earth day.

Rationale: PNT services can be met with more available and mature S and X systems. Dedicated PNT coverage is needed for Artemis vehicle autonomy in lunar space. Availability of these services can be increased without undue burden on the development effort.

Phase: IOC, EOC

LCRNS.3.0120 Lunar Augmented Navigation System (LANS) Service The Lunar Relay Service shall provide Lunar Augmented Navigation System (LANS) services for 98% of any operational service period covering the lunar south pole (80° - 90° South).

Rationale: Availability of these services will be targeted to support initial IOC missions, with full lunar coverage attained in EOC. The LANS consists of more than one AFS signal.

Phase: IOC

LCRNS.3.0130 Lunar LANS Service Geometric Dilution of Precision (GDOP) The Lunar Relay Service shall provide LANS services with Geometric Dilution of Precision (GDOP) 2 (TBR) globally over the moon 98% (TBR) of the time.

Rationale: GDOP is fundamental in achieving performance, in terms of knowledge and timeliness to meet user needs. Note that “time” refers to all time, as it is expected there will always be some user (human or robotic) to service during

EOC.

Phase: EOC

LCRNS.3.0140 Lunar Service Situational Awareness The Lunar Relay Service shall share relay ephemeris knowledge with other providers.

Rationale: NASA seeks an interoperable network with national and international participants. The ability to share relay information with respect to their orbital ephemerides enables a true navigation network, prevents collisions, and allows scheduling of assets without ground intervention. In IOC ephemeris sharing can be done indirectly through an Earth facility.

Phase: IOC, EOC

LCRNS.3.0150 Time Synchronization The Lunar Relay Service shall synchronize time with an external common reference timing source shared with other providers.

Rationale: NASA seeks an interoperable network, per the LunaNet Interoperability Specification, with national and international participants. The ability to share relay information with respect to their orbital ephemerides enables a true navigation network, prevents collisions, and allows scheduling of assets without ground intervention.

Phase: IOC, EOC

LCRNS.3.0160 Provider to Provider Message Exchange The Lunar Relay Service shall support messaging services between different providers, enabling exchange of navigation, schedule and space situational awareness information.

Rationale: NASA seeks an interoperable network with national and international participants. The ability to share relay information with respect to their orbital ephemerides enables a true navigation network, prevents collisions, and allows scheduling of assets without ground intervention.

LCRNS.3.0170 Dynamic Phases The Lunar Relay Service shall cover dynamic events such as lunar vehicle descent and ascent, lunar orbiting vehicles, and mobility surface vehicles and personnel.

Rationale: The dynamic environment of lunar systems will require sufficient coverage to support precise navigation, DTE communications blockage, and search and rescue operations. Descent to the lunar surface includes landing;

ascent includes lift-off from the lunar surface.

Phase: IOC, EOC

LCRNS.3.0180 Dynamic Coverage (HLS) – Low Lunar Orbit (LLO) The Lunar Relay service shall provide communications and PNT services to HLS in a low lunar orbit.

Rationale: The relay must be able to provide service while tracking user spacecraft in motion relative to the lunar surface. A low lunar orbit generally refers to 100 kilometers (TBR) altitude and below.

Phase: IOC, EOC

LCRNS.3.0190 Dynamic Coverage (HLS) – Descent The Lunar Relay Service shall provide continuous communications and PNT services to HLS while descending to the lunar surface from LLO.

Rationale: The LCRNS Relay must be able to provide service while tracking user spacecraft in motion relative to the lunar surface. Descent to the lunar surface includes landing.

Phase: IOC, EOC

LCRNS.3.0200 Dynamic Coverage (HLS) – Ascent The Lunar Relay Service shall provide continuous communications and PNT services to HLS while in ascent from the lunar surface to LLO.

Rationale: The LCRNS Relay must be able to provide service while tracking user spacecraft in motion relative to the lunar surface. Ascent includes lift-off from the lunar surface.

Phase: IOC, EOC

LCRNS.3.0210 Surface User Operations The Lunar Relay Service shall provide communications and PNT services to users while on the lunar surface.

Rationale: The LCRNS Relay must be able to provide service on the lunar surface.

Phase: IOC, EOC

LCRNS.3.0220 EVA surface operations The Lunar Relay Service shall provide communications and PNT services to the EVA users.

Rationale: EVA users while out of line of sight of the HLS, LTV, or other mobile communications platforms will rely on lunar relay services (not UHF) for communication and PNT services. Coverage to EVA directly is possible if suits are so equipped.

Phase: IOC, EOC

LCRNS.3.0230 EVA surface extended Operations Duration The Lunar Relay Service shall provide navigation services such that the NASA human spaceflight architecture on the lunar surface can meet a minimum of 24 hours of cumulative surface EVA time per crewmember per 7 Earth-day period during surface stays greater than or equal to 14 Earth-days.

Rationale: The primary goal of Lunar Relay is to enable communication between the crew and mobility assets on the lunar surface and the Earth. EVA elements will be able to use Lunar Relay Services for specific operational needs.

Phase: EOC

LCRNS.3.0240 EVA surface initial Operations Duration The Lunar Relay Service shall provide PNT services so that the initial Artemis systems can be capable of supporting at least two lunar surface extra-vehicular activities (EVA), each lasting at least four hours nominally with a one-hour contingency.

Rationale: The lunar relay service needs to cover the entirety of EVA operations as relayed through the HLS lander (IOC). This will both cover instances where DTE is not available and provides a backup to DTE if it is available.

Phase: IOC, EOC

LCRNS.3.0250 LTV surface operations The Lunar Relay Service shall provide communications and PNT services to the

LTV.

Rationale: The LTV, while out of line of sight of the HLS or DTE, will rely on Lunar relay services for communication and PNT services.

Phase: IOC, EOC

LCRNS.3.0260 User Data Security The Lunar Relay Service shall maintain user provided encryption sent to and from the lunar relays and Earth ground stations.

Rationale: Lunar relays will maintain user data encryption as it moves to and from endpoints – no decryption of user data through the relay path will be provided (TBR for EOC capabilities).

Phase: IOC, EOC

LCRNS.3.0270 Earth Independent Services The Lunar Relay Service shall provide services between endpoints in the lunar vicinity without routing data to and from Earth.

Rationale: Routing data to and from Earth increases Earth-station usage, raises latency, and reduces throughput, versus routing data entirely in the lunar domain.

LCRNS.3.0280 Real-time Data Latency The Lunar Relay Service node shall limit the time between receiving real-time data and transmitting that data to less than 1.0 (TBR) seconds.

Rationale: Each relay node must limit on board processing of real-time data (voice, video, telemetry) to the minimum needed so as not to be disruptive to end-user operation. The current estimate is 5 seconds end-to-end from users on earth to users on the lunar surface. Each relay node is allocated 1.0 second. Does not include light time delays.

Phase: IOC, EOC

LCRNS.3.0310 Earth Forward or Return Latency The Lunar Relay Service shall limit the time between receiving/transmitting real-time data from a user to the less than 3.0 (TBR) seconds each way.

Rationale: Command data is related to the real-time health and safety of the user mission platform and must be delivered to the mission platform quickly.

Phase: IOC, EOC

LCRNS.3.0320 Concurrency of Operations The Lunar Relay Service shall provide concurrent operations of relay services for lunar communications, data operations, PNT services, and search and rescue

(SAR).

Rationale: The lunar relay service needs to provide concurrent communications, real-time, store and forward data, and PNT services with one or more lunar users while maintaining high data rate and low latency operations.

Phase: IOC (all but Lunar SAR, which is EOC), EOC

LCRNS.3.0330 Lunar Relay Function Compatibility The Lunar Relay Service shall interface with Lunar User Systems and provide communication and PNT services within an interoperable framework.

Rationale: The primary goal of lunar relay is to enable communication and PNT services between the crew and mobility assets on the lunar surface and the Earth.

Artemis elements will be able to use lunar relay, Gateway or other assets interchangeably depending on specific needs.

Phase: IOC, EOC

LCRNS.3.0340 Ground Station (commercial or government) Interface to the

NSN

The Lunar Relay Service shall interface with the NSN demarcation point in the Cloud.

Rationale: An interoperable network will need a way to deconflict data services to/from users on Earth and in lunar space. The NSN provides a central hub where multiple providers are deconflicted and appropriate services selected. Assumes service provider has a mission operations center to manage and control the relay service nodes and includes the information necessary for its own flight operations.

LCRNS.3.0421 Forward Signal Acquisition The Lunar Relay Service shall provide a swept unmodulated carrier during forward acquisition.

Rationale: This is a service that modern ground stations provide, and spacecraft missions have come to expect- does not include AFS service.

Phase: IOC, EOC

LCRNS.3.0422 Return Signal Acquisition The Lunar Relay Service shall be capable of locking onto a modulated carrier during return acquisition.

Rationale: It is commonplace to put the burden of acquisition on the network side in order to reduce complexity of the user mission. This is a capability that modern ground stations have.

Phase: IOC, EOC

LCRNS.3.0430 Service Simultaneity The Lunar Relay Service shall be capable of simultaneously providing all the data rate services (high-rate forward, high-rate return, low-rate forward, low-rate return) to a single user.

Rationale: This will allow back-up monitoring of spacecraft telemetry while providing a high-rate link for video transmissions.

Phase: IOC, EOC

LCRNS.3.0440 Simultaneous User Coverage (Low Rate) The Lunar Relay Service shall be capable of providing a bidirectional high-rate service to one user while simultaneously providing a bidirectional low-rate service to another user.

Rationale: This will allow monitoring of spacecraft telemetry for one user while providing a high-rate link for video transmissions to another. It may be assumed that both users are within close proximity to one another.

Phase: IOC, EOC

LCRNS.3.0450 Simultaneous User Coverage (High Rate) The Lunar Relay Service shall be capable of providing a bidirectional high-rate service to one user while simultaneously providing a bidirectional high-rate service to another user.

Rationale: It may be assumed that both users are within close proximity to one another.

Phase: IOC, EOC

LCRNS.3.0470 Dynamic Signal The Lunar Relay Service shall be capable of maintaining the communication and navigation links through the dynamic mission reference trajectories shown in Appendix B [TBR].

Rationale: This requirement implies tracking loop requirements (doppler) and antenna slewing or beamforming requirements to support HLS descent and ascent.

LCRNS.3.0480 Multiple Access Return Signal The Lunar Relay Service shall implement Multiple Access Return Signal per the LunaNet Interoperability Specification for low-rate S-band only.

Rationale: Needed to support EVA and LunarSAR for more than one user at a time.

Phase: EOC

LCRNS.3.0490 Cross-Link Capability The Lunar Relay Service shall provide interoperable cross link support between its own nodes and those nodes of other service providers per the LunaNet Interoperability Specification to provide for communication, data services, and intersatellite PNT.

Rationale: Assumes multiple providers working together within one lunar communications and navigation network. Providers are expected to develop capabilities to measure intersatellite range and Doppler, exchange and synchronize time, and exchange position and velocity as well navigation sources in compliance with the LunaNet interoperability specification among their own nodes and with other providers independent from Earth.

Phase: EOC

3.2.2 Space Internetworking Data Service Requirements

The network requirements are the aggregation of requirements for all data flows between all sources and destinations flowing through lunar relays.

LCRNS.3.0500 Data Service Capabilities The Lunar Relay services shall support the following data service capabilities: (a) real-time data services, (b) store-and-forward data services.

Rationale: Users requesting data service from lunar relays need to understand which nodes support their desired data service capabilities. The lunar relay service needs to provide real-time service for those users having specific low latency requirements and provide store and forward service to those users with flexible latency requirements.

Phase: IOC, EOC

LCRNS.3.0510 Protocol Configuration The Lunar Relay Service shall be able to configure their protocol to communicate with all compatible user missions.

Rationale: Users requesting data service from lunar relays need to understand which nodes support the unique protocol configurations and constraints of their configurations which must be followed when connecting to various relay nodes.

Phase: IOC, EOC

LCRNS.3.0520 Store and Forward/Disruption Tolerant Network (DTN) The Lunar Relay Service shall implement DTN BPv7 with custody transfer to provide store and forward data transfers.

Rationale: DTN is the most effective means of ensuring data delivery when disruptions to signal path occur and are extensible to the entire solar system.

Phase: IOC, EOC

LCRNS.3.0530 DTN Reliability The Lunar Relay Service DTN shall provide reliable delivery of bundles at or exceeding 95% (TBR) successful delivery.

Rationale: User missions rely on the lunar relay services to provide consistent and dependable service to receive and distribute mission data. Reliable delivery of bundle service is dependent on the availability of the overall lunar relay network.

Phase: IOC, EOC

LCRNS.3.0540 DTN Routing Rate The Lunar Relay DTN Service shall provide a minimum bundle generation and throughput rate no less than the maximum relay data rates as defined in this document.

Rationale: DTN service data ingest, processing, storage, and output rates must not be a bottleneck in data throughput, and so must process inbound and outbound data as fast as or faster than the maximum aggregate input and output rates of all communications channels that use DTN, and consistent with available per-minute contact times.

Phase: IOC, EOC

LCRNS.3.0550 DTN Storage Accounting The Lunar Relay DTN Service shall maintain a centralized storage of service accounting and network and node status information and make this accessible for accounting purposes.

Rationale: The NSN will need to collect, store and account for user data to meet user needs and required QOS metrics.

Phase: IOC, EOC

LCRNS.3.0560 Intermediate DTN Bundle Storage The Lunar Relay DTN Services shall be capable of storing bundles at intermediate relay nodes during bundle routing.

Rationale: The relays will need to provide sufficient intermediate storage of data to meet mission requirements and provide accounting information for such data to satisfy user data accounting needs.

Phase: IOC, EOC

3.2.3 Position, Navigation, and Timing (PNT) Services

The lunar communications and navigation service shall provide functionality for in-situ autonomous lunar orbiting and surface asset navigation and time knowledge to meet their mission requirements. PNT services support human and robotic spacecraft and astronauts, particularly during dynamic phases (low-lunar orbit, during descent and ascent, and during long EVAs). Table 3-7 and Table 3-8 describe representative user scenarios and their associated PNT performance requirements for IOC and EOC respectively. PNT performance in these tables include position and velocity knowledge, time for first fix, time delay to meet knowledge update and time knowledge. All position and velocity numbers are given as RSS values of position and velocity component errors, except for the landing scenario which is specified for position as a landing radius on the surface and a velocity requirement per axis. Time to first fix is defined as the time it takes to get an initial fix in the scenario environment or recover the position knowledge after a propulsive maneuver (except landing).

Time delay to meet knowledge is the time it takes to update position knowledge (when relays are in view) and this includes landing scenario radiometric update rate.

There are currently seven user scenarios defined for PNT. The first scenario represents an asset in low lunar orbit (≤ 100 km from the lunar surface). The navigation solution in that case can either be accomplished on the ground or on-board, depending on the user’s operational concept. The second scenario describes lander type missions at the time prior to starting their powered descent to the surface (e.g., at 15 km from the lunar surface). The state and time knowledge in that user scenario is primarily envisioned to initialize an on-board full 6-DOF solution. The landing user case addresses the knowledge portion of a given landing touchdown, assuming that the lander is equipped with hazard and detection capabilities. The remaining four user cases relate to PVT knowledge during surface activities: general case while static on the lunar surface, instance of a traversing user on the surface (e.g., 2 km/h walking speed), sample-collecting activities and installation of science instruments or localization of in-situ resources. For the EOC phase, a lunar rover is envisioned as part of the surface traversing user case with higher speeds (e.g., 10 km/h moving speed). Note that while these are representative of the user landscape in IOC and beyond, it is expected that providers will work with future individual users to further refine and capture their navigation needs.

Rationale: The lunar relays shall be capable of providing 2-way measurements, especially for users that do not accommodate the use of reference signals.

Phase: IOC, EOC

LCRNS.3.0620 Interoperability of PNT Services The Lunar Relay Service shall have the ability to provide the messages defined in the LunaNet Interoperability Specification, commensurate with Table 3-9 and Table 3-10.

Rationale: Service interoperability is essential to behave as a single functional network composed of contributions from multiple LNSPs.

Phase: IOC, EOC

3.2.4 Lunar Search and Rescue (LunarSAR) Services

LCRNS.3.0630 LunarSAR Emitter Probability of Detection The Lunar Relay Service shall provide a probability of detection of 99% within 5 minutes [TBR] of activation, for a LunarSAR beacon transmitting a LunarSAR-compliant message at 35 dBm [TBR] EIRP.

Rationale: High probability of detection is required to ensure timely distress rescue coordination and response for future governmental, commercial, and private lunar exploration efforts utilizing internationally standardized LunarSAR message formatting and transmission EIRP requirements.

Phase: EOC

LCRNS.3.0640 LunarSAR Detection Dissemination The Lunar Relay Service shall notify Relay users of LunarSAR beacon detection within 5 minutes [TBR] of beacon activation.

Rationale: Distress event dissemination is a key cornerstone of SAR operations, and consequent lunar surface actions.

Phase: EOC

LCRNS.3.0650 LunarSAR Service Availability The Lunar Relay Service shall provide LunarSAR Service availability of 99% (TBR) during scheduled EVA periods.

Rationale: High availability rates are required to ensure timely distress rescue coordination and response for future governmental, commercial, and private lunar exploration efforts utilizing internationally standardized LunarSAR message formatting and transmission EIRP requirements. High coverage percentages are paced with the development of the overall lunar concept of operations, i.e., as Artemis focuses on lunar south pole activities, LunarSAR service availability will evolve in the lunar south pole. Lunar Relay Service and EVA schedules may be coordinated to meet this requirement.

LCRNS.3.0660 LunarSAR Message Relay Timeline The Lunar Relay Service shall relay the entire beacon message(s), beacon encoded position(s), and timestamps to Earth and selected lunar surface locations within 5 minutes [TBR] of beacon activation.

Rationale: The timeline between LunarSAR beacon activation and reception/processing of LunarSAR data drives response timeframes and ability to successfully perform crewmember rescue operations over extended EVA walk-back distances. Future SAR cases may involve a mixed ecosystem of commercial, international, and governmental users requiring timely coordination and ability to disseminate information.

Phase: EOC

LCRNS.3.0670 LunarSAR Independent Location Probability The Lunar Relay Service shall provide a probability of independent location (not relying on LunarSAR beacon-provided location data) of 95% within 10 minutes [TBR] of activation, for a LunarSAR beacon transmitting at 35 [TBR] dBm EIRP.

Rationale: As a future capability, the relay constellations should provide “reverse GPS” for disadvantaged users in potentially PNT-degraded environments (i.e., PNT signal terrain masking or other terrain features causing multipath propagation effects). This aligns with current terrestrial satellite-aided search and rescue (SARSAT) principles for those in potentially degraded GNSS environments.

Phase: EOC

LCRNS.3.0680 LunarSAR Independent Location Accuracy The Lunar Relay Service shall locate an emergency beacon within the Lunar South Pole region with an accuracy of 50 meters [TBR], without reliance on the beacon’s self-reported position for a LunarSAR beacon transmitting at 35 [TBR] dBm EIRP.

Rationale: As a future capability, The LCRNS relay constellations should provide “reverse Global Positioning System (GPS)” for disadvantaged users in potentially PNT-degraded environments (i.e., PNT signal terrain masking or other terrain features causing multipath propagation effects). This aligns with current terrestrial satellite-aided search and rescue (SARSAT) principles for those in potentially degraded GNSS environments.

Phase: EOC

3.2.5 Lunar Relay Service On-orbit Validation Capabilities

LCRNS.3.0690 On-board self and built-in service testing Each Lunar Relay service node shall have internal built-in test and verification capability.

Rationale: Unlike typical earth communication relays, the lunar relay nodes will be performing other services to route, store and forward user data and provide accurate location and position information with lunar user elements. Some method of verifying these services (or degraded services) must be internal to the relay to validate prior to operational certification with the possibility there may not be lunar users available to test services. This includes verifying its operation after recovery from critical faults on-orbit.

Phase: IOC, EOC

3.2.6 Lunar Relay Cybersecurity

LCRNS.3.0700 Command Data Encryption Each Lunar Relay service node shall use FIPS 140-3 certified encryption for all spacecraft commands.

Rationale: Command data must be protected to ensure that only authorized users have access to the system and all services are available during critical events. This must be verified against the NIST FIPS 140-3 Cryptographic Module Validation Program and the communication path must be tested to ensure compatibility between ground infrastructure and space segment prior to launch.

Phase: IOC, EOC

LCRNS.3.0710 Information System Authorization The lunar relay providers ground system shall be assessed and authorized as a HIGH system in accordance with the Federal Information System Management Act of 2014 using NIST Special Publication 800-53, Revision 5.

Rationale: All systems processing data for or on behalf of NASA are required to follow the NIST Risk Management Framework and conduct regular assessments and perform continuous monitoring activities.

Phase: IOC, EOC

LCRNS.3.0720 Project Protection Plan The lunar relay provider shall complete and update a Project Protection Plan (PPP) to identify known threats and response plans to mitigate associated risks.

Rationale: NASA requires each flight system to complete and maintain a PPP that addresses known risks identified in NASA-STD-1006.

Phase: IOC, EOC

LCRNS.3.0730 Service Authentication The lunar relay PNT service shall have the capability to provide authentication to users.

Rationale: The use of authentication will provide resistance to spoofing and ensure that PNT data is coming from a legitimate source.

Phase: IOC, EOC

LCRNS.3.0740 Service Availability Protection The lunar relay system shall have anti-jamming capabilities to prevent denial of service via Radio Frequency Interference (RFI) or other electronic attack.

Rationale: The inclusion of anti-jamming capabilities will help ensure that events could not be intentionally disrupted by a malicious actor.

observables are used to estimate user Position, Velocity and Time (PVT). However, in IOC there may be a need for the user to supplement the set of observables from relay(s) with other data sources, such as DTE (Earth to lunar user). The relays shall provide messages with all the information content related to the network that is required by the user to perform their PVT solution.

The user terminal is expected to have the capability to receive signals from multiple relays simultaneously and process the metric tracking observables and message content to obtain a PVT solution.

3.3.3 User Timelines

The following list is a general reference of expected NASA users requiring relay service in lunar space starting in 2024.

• HLS Test Mission: as early as June 2024

• NASA payloads on first Far Side CLPS mission: as early as October 2024

(Schrodinger Basin)

• Artemis III HLS Mission: as early as July 2025 (South Pole region)

• Lunar Terrain Vehicle: as early as 2026 (South Pole region)

• Subsequent Artemis HLS missions: up to one per year beginning as early as in 2026 (South Pole region)

• NASA payloads on subsequent CLPS missions potentially requiring relay service

- up to one South Pole region mission per year beginning as early as 2025

- up to one Far Side mission every two years beginning as early as 2026

During Artemis missions, communication demand will also impact NASA’s ability to provide DTE communication services to science missions. LNSP support will help “offload” NASA’s DTE communication services via allocated LNSP lunar relay-Earth ground station assets.

In addition, baseline support to lunar science missions is also anticipated. These science missions include Lunar orbiting and lunar surface missions. A key surface mission on the lunar far side would have no way of returning its science data to Earth without a lunar relay. Other surface science missions could include missions near the Lunar south pole, and other locations including various locations near the lunar equator.

The following tables represent a summary of anticipated mission demand over the course of each Artemis mission. This table is based on many assumptions which will change as Artemis and other missions provide initially their concept of operations and later detailed flight operations over their development lifecycle. The purpose of this section is to provide insight on the current tentative picture of the stressing relay communication support to be fulfilled. Lunar orbit refers to any orbit around the moon.

3.3.4 Reference Trajectories for Descent and Ascent

Figure B-1 gives the NASA reference trajectory for HLS landing to the lunar surface.

Figure B-2 gives the reference ascent trajectory. These are given for specific dates and may be used to scope the dynamic service coverage for landing human systems.

Figure B-1 NASA Reference Trajectory for HLS Landing

Figure B-2 NASA Reference Trajectory for HLS Departure