I. Introduction

NASA’s Artemis missions will return humanity 

to the Moon, establishing a long-term presence 

there and opening more of the lunar surface to 

exploration than ever before. This rapid growth 

of lunar activity requires robust and resilient 

communications, navigation, and networking 

capabilities for crew safety, command and 

control of spacecraft, return of science data, 

and precise maneuvering of assets in space and 

on the lunar surface.

Within the Moon to Mars Architecture,[1] the 

Communications, Position, Navigation, and 

Timing (CPNT) sub-architecture details the 

specific CPNT systems, functions, and use 

cases required to meet the NASA’s Moon to 

Mars Objectives throughout each segment of 

the architecture. The CPNT sub-architecture 

through the Human Lunar Return segment — 

approximately through Artemis V — is detailed 

here. 

The architecture development effort utilizes 

an objectives-based approach that focuses on 

the ultimate goals of human exploration of the 

Moon, Mars, and beyond.[2] The three objectives 

most fundamental to the CPNT sub-architecture 

are: 

• Develop a lunar surface, orbital, and Moonto-Earth communications architecture 

that scales to support long-term science, 

exploration, and industrial needs.

• Develop a lunar position, navigation, and 

timing (PNT) architecture that also scales to 

support long term science, exploration, and 

industrial needs. 

• Preserve and protect representative 

features of special interest, including the 

shielded zone of the Moon. 

II. Lunar Communications Architecture

The CPNT sub-architecure enables 

communication and navigation on the lunar 

surface, in cislunar space, and with Earth. Use 

cases allocated to the CPNT sub-architecture 

include: 

• Crew voice and data communications.

• Video for scientific data collection, public 

outreach, and crew safety.

• Science data transmissions across:

» Direct-to-Earth communications. 

» Communications among surface 

assets, orbiting relays, and Gateway, 

NASA’s lunar-orbitting space station. 

» Lunar surface-to-surface 

communications. 

PNT use cases include providing position and 

timing of lunar samples, to crew navigating the 

surface, for landings and ascents, and to other 

cislunar assets. NASA will lead a distributed 

team of government, commercial, and 

international partners to implement the CPNT 

sub-architecture on Earth, in cislunar space, 

and on the lunar surface. 

Cooperation among multiple service providers 

and users across government, industry, and 

international partners requires coordination 

and planning through established and new 

interface and operations standards. This will 

enable a long-term, scalable, and interoperable 

architecture that provides communications 

services across all the assets.

Beginning with the initial Human Lunar Return 

segment of the architecture, a variety of 

interface standards will enable interoperability. 

These include the LunaNet Interoperability 

Specification, the International Communication 

Systems Interoperability Standard, terrestrial 

wireless cellular standards, and other similar 

coordination with industry and international 

partners.[3,4,5]

LunaNet is an internationally coordinated 

framework for lunar interoperability, envisioned 

as a set of cooperating networks providing 

communications, navigation, and other services 

for users on and around the Moon. The LunaNet 

concept is based on a structure of mutually 

agreed-upon standards, protocols, and interface 

requirements that enable interoperability. 

National Aeronautics and

Space Administration

2023 Moon to Mars Architecture Concept Review 1white paper 2023 Moon to Mars Architecture

NASA’s Lunar Communications 

and Navigation Architecture
2023 Moon to Mars Architecture Concept Review 2

The International Communication Systems Interoperability Standard was developed to enable collaborative 

operations. These systems provide end-to-end compatibility and interoperability between a cislunar space platform, 

visiting spacecraft, lunar systems, and Earth. 

Figure 1 illustrates the principal CPNT architecture during early exploration segments, including Human Lunar Return.

[6] Ground stations from multiple providers offer connectivity direct to the lunar surface and to communications relays 

or assets in lunar orbit. Surface communications occur between crew and landing vehicles using a wireless network. 

Equipped surface assets communicate with Gateway and via orbital relays to Earth.

A. Direct-to-Earth Communications

For users near the lunar South Pole, communications 

with Earth are complicated by the orbital geometry of the 

Earth-Moon system. The Moon’s orbital inclination — the 

tilt of its orbit around Earth — and obliquity — the tilt of its 

rotational axis — cause Earth to be visible from the lunar 

South Pole for only about half of every sidereal month, 

the time it takes the Moon to orbit once around Earth 

(approximately 14 days). This will require deployment of 

orbiting relays to maintain continuous communications. 

Furthermore, the topography of the polar regions is 

unlike the lunar maria, the large plains visited by the 

Apollo missions, or any region on Earth. For example, 

Shackleton Crater — a dominant feature of the lunar 

South Pole — is over two times deeper than the Grand 

Canyon. Nearby regions of interest are challenging for 

rovers and astronauts to traverse and safely navigate 

while maintaining reliable communications. 

Additionally, when Earth is visible from the lunar South 

Pole, it is always seen near the Moon’s horizon. The lunar 

terrain can also adversely affect communications signals 

traveling over it.[7]

Direct-to-Earth communications for Gateway and lunar 

missions will be supported by NASA’s Deep Space 

Network facilities, NASA’s Near Space Network’s future 

Lunar Exploration Ground Systems, the European Space 

Agency’s European Space Tracking (ESTRACK) network, 

and commercial ground assets. Together, these will 

provide near-continuous coverage to Gateway and the 

lunar South Pole when in Earth’s view. 

Projected communication needs beyond Human Lunar 

Return are expected to exceed the planned radio 

frequency communications capacity. Future optical 

communications capabilities, which use infrared lasers to 

provide higher data throughput, will accommodate the 

increased data volume at the Moon. 

B. Orbiting Communication Relays

To close the gaps in direct-to-Earth communications, 

NASA is pursuing commercial satellite services to provide 

connectivity for missions on the lunar surface and in

cislunar space. These providers will employ lunar-orbiting 

relay satellites with downlinks to commercial ground 

stations on Earth. Additionally, Gateway will provide

Figure 1. The CPNT Architecture for Early Lunar Exploration
2023 Moon to Mars Architecture Concept Review 3

communication links and limited PNT functions for 

surface and in-orbit users. International space agencies 

are also considering lunar communications relays, which 

may hold potential for collaboration.

The Lunar Communications Relay and Navigation Services 

project will provide consistent availability, visibility, and 

higher data rates for surface users. With multiple relays 

incrementally launched, the project can offer phased and 

incremental coverage of the South Pole region.[3] Early 

implementations will also offer preliminary PNT services 

as a stepping stone to a more robust, dedicated capability 

beyond the Human Lunar Return segment. 

C. Surface Communications

NASA is pursuing trade studies on different approaches 

to lunar surface networking to select implementations 

that best meet the exploration requirements. These 

potential approaches include: 

• Adapting NASA’s Space-to-Space Communication 

System — a two-way communications system 

designed to provide voice and telemetry data between 

the space shuttle orbiter, the International Space 

Station, and the Extra Vehicular Activity Mobility Unit 

— at ultra-high frequency for voice communications.

• Using Wi-Fi for close-proximity high-rate video 

communications.

• Leveraging terrestrial wireless cellular standards for 

scalable, longer range, high-throughput connectivity 

with PNT services.[8] Such a network could enhance 

exploration range and mobility and the aggregation 

of data between a variety of science users. 

Figure 2 illustrates the anticipated excursion ranges (e.g., 

a 2km extravehicular activity range) with different surface 

networking implementations, compared to exploration 

distances of Apollo 17.[9] Specific communications range 

distances can extend beyond those illustrated in the figure 

with varying data throughput. These ranges will also vary 

by system design choices and other considerations. 

The combination of proposed approaches should 

meet exploration requirements. Range needs will vary 

by mission, driven by exploration objectives, crew 

mobility capabilities, and landing site considerations 

and constraints, such as terrain, slope, and regolith 

displacement due to landing. 

During the Human Lunar Return segment, initial CPNT 

infrastructure concepts, capability, and hardware 

elements will be demonstrated through technology 

demonstrations and initial operational support. The 

expansion to longer term, sustainable implementation 

of a lunar surface network will occur during subsequent 

segments, incorporating advancements and lessons 

learned from technology demonstrations.

Figure 2. A Comparison of Estimated Ranges for Several Surface Network Implementations, 

Plotted against the Longest Apollo-era Traverses with the Lunar Roving Vehicle during Apollo 17.
III. Lunar Position, Navigation, 

and Timing Architecture

The lunar PNT architecture provides core functions to 

users on the Moon and in cislunar space. PNT capabilities 

allow lunar assets to know their current position, velocity, 

and time, and to navigate safely in lunar orbit and on the 

Moon’s surface. Real-time, precise PNT services benefit the 

breadth of lunar users and scenarios, including orbiters, 

landers, surface exploration, and image and science 

collection. PNT needs vary from a Human Landing System 

accuracy requirement of within 100 meters of a planned 

landing site, surface position accuracy requirement of 

within 50 meters, and surface sample location marking 

accuracy requirement of within 10 meters. 

There are a number of challenges associated with PNT on 

the lunar surface. Traditional methods of tracking by Earth 

networks will be difficult, if not impossible, during surface 

operations on the South Pole when users have limited 

or no line of sight to Earth. Use of GPS at the Moon is 

limited by the weakness of GPS signals at lunar distances, 

GPS satellite geometry, and occultation, where Earth 

blocks GPS signals from reaching the Moon. The variable 

lighting environment and challenging terrain conditions 

will make it difficult for the crew to use orienteering or 

camera-based approaches. 

NASA’s navigation architecture is comprised of both 

infrastructure and user capabilities. Infrastructure 

includes critical reference system components and 

radionavigation sources provided via communications 

and network assets. User-side capabilities include the 

onboard navigation systems that collect, process, and 

filter the data required to successfully navigate. 

A. Infrastructure

Radio frequency (radiometric) sources are the most 

traditional means of navigation for spacecraft from 

near-Earth to deep space. At the Moon, these sources 

will include ground stations on Earth, satellites in orbit 

around Earth and the Moon, and assets on the lunar 

surface. 

Earth-based Global Navigation Satellite System (GNSS) 

PNT services, like those provided by the U.S. Global 

Positioning System (GPS) constellation, can extend to 

the lunar regime in certain circumstances. These GNSS 

signals can aid the data diversity for resilient navigation 

when combined with traditional deep space signal 

tracking methods. 

Communications relays in lunar orbit will provide cislunar 

and surface PNT services by broadcasting reference 

signals. One such approach, an augmented forward 

signal, combines navigation information with broadcast 

data messaging.

During the Human Lunar Return timeframe, NASA will roll 

out PNT capabilities across the early Artemis missions. 

This will begin with PNT provided by Earth-based tracking 

and surface elements, and expand to services provided 

by an initial relay satellite in luanr orbit. Subsequent 

to the Human Lunar Return segment, additional relay 

satellites could be supplied for a GNSS-like PNT capability 

that covers the global lunar service volume. 

B. User Capabilities

In addition to using radiometric measurements from 

Earth, lunar orbit, and surface assets, lunar users will 

employ any number of other navigation data sources. 

These could include cameras and optical sensors, light 

detection and ranging (lidar) payloads, solar compasses, 

and inertial measurement units, which can use a 

combination of accelerometers, gyroscopes, and other 

tools to determine specific force, angular rate, and 

orientation. 

During the Human Lunar Return phase, NASA will plan 

surface operations during well-illuminated conditions, 

allowing missions to rely largely on orienteering with use 

of maps, solar compass, and inertial measurement units. 

Additional sensors such as cameras or light beacons from 

a lunar lander will also be considered.

IV. Conclusion

The Moon to Mars CPNT sub-architecture defines the 

relevant functions necessary to achieve high availability, 

high throughput communications, and accurate PNT to 

enable the safe command and control of spacecraft, the 

return of science data, and precision maneuvering of 

assets. Together, these functions will enable the longterm goals laid out in NASA’s Moon to Mars Objectives. 

Through the Human Lunar Return segment, CPNT subarchitecture needs will be met through a combination 

of direct-to-Earth, space-based relay, surface-to-surface 

communications, navigation assets, and in-situ sensors. 

Deep Space Network facilities, upgraded to support 

additional Ka-band frequencies, and the Near Space 

Network’s Lunar Exploration Ground Systems will provide 

near-continuous coverage of the lunar South Pole when 

in view from Earth and to Gateway. The European Space 

Agency’s ESTRACK network will provide support for 

Gateway alongside potential commercial services from 

ground stations and lunar relay satellites, which could 

also support other cislunar and surface users. 

Commercial and international partnerships will be 

key to developing a robust CPNT sub-architecture. 

During the Human Lunar Return segment, incremental 

improvements will facilitate more efficient network 

scheduling and utilization as a first step toward a more 

robust network management framework. These efforts 

are intended to meet the needs of near-term exploration 

and scale to support the increasing complexity of longterm lunar science and exploration.

2023 Moon to Mars Architecture Concept Review 4
2023 Moon to Mars Architecture Concept Review 5

References

1. “Moon to Mars Objectives,” National Aeronautics and Space Administration, Washington, DC, 2022.

2. S. Li, P. Lucey, R. Milliken, P. Hayne, E. Fisher, W. Jean-Pierre, D. Hurley and R. Elphic, “Direct Evidence of Surface 

Exposed Water Ice in the Lunar Polar Regions,” Proceedings of the National Academy of Sciences, vol. 115, no. 

36, pp. 8907-8912, 2018. 

3. “LunaNet Interoperabilty Specification,” National Aeronautics and Space Administration, Washington, DC, 2022.

4. “International Communication System Interoperability Standards,” National Aeronautics and Space 

Administration, Washington, DC, 2020.

5. “Communication and Positioning, Navigation, and Timing Frequency Allocations and Sharing in the Lunar 

Region,” Space Frequency Coordination Group, 2022.

6. P. A. Baldwin, G. W. Heckler, A. Petro, J. Schier, J. Berner, W. Evans and E. Weir, “Space Communications in 

Support of the Artemis Program,” in 16th International Conference on Space Operations, Cape Town, South 

Africa, 2021. 

7. N. Rodriguez-Alvarez, M. Net, D. Kahan and D. Morabito, “Multipath Measurements at the Lunar South Pole from 

Opportunistic Ground-based Observations - Part II: Experiment Results,” IPN Progress Report 42-226, 2021. 

8. B. Edwards, R. Wagner, M. Zemba, W. Millard, S. Braham, K. Gifford and O. Somerlock, “3GPP Mobile 

Telecommunications Technology,” in IEEE Aerospace Conference, Big Sky, 2023.

9. Technical University Berlin, German Aerospace Center (DLR) LROC Team, “Moon Apollo 17 LROC NAC Landing 

Site Orthomosaic 50cm v1”, USGS Astrogeology Center. August 2018, 2010. [Online]. Available: https://

astrogeology.usgs.gov/search/map/Moon/Apollo/Traverse/Apollo17/Apollo17_landing_site_map_scale15000. 

[Accessed 2023].

Contributing Authors

• Michael Zemba, NASA’s Glenn Research Center

• Karl Vaden, NASA’s Glenn Research Center

• Richard Reinhart, NASA’s Glenn Research Center

• Cheryl Gramling, NASA’s Goddard Space Flight Center

• Greg Heckler, NASA Headquarters