月版GNSS（Lunar
Augmented Navigation
Service）における欧米日の連携と実証ミッションについて
村田眞哉（JAXA）

Lunar Comm&Nav (CPNT) systems by US, Europe, Japan
ESA Moonlight
LCNS(2027～)

JAXA LNSS(2028～)

NASA LCRNS(2025～)

LCNS:
Lunar Communications
Navigation Services

LCRNS:
Lunar Communications Relayand Navigation Systems
LNSS:
Lunar Navigation Satellite System

Towards the establishment of the Moon GNSS (LANS)
The concept of the Moon GNSS called the Lunar Augmented Navigation Service (LANS)
Augmented
Forward Signal(AFS)

Augmented
Forward Signal(AFS)
All broadcast thestandardized AFS toform LANSJAXA LNSSsatellite
NASA LCRNS satellites
ESA Moonlight(LCNS) satelliteThis figure was copied from the LunaNet Interoperability Specification (LNIS)※LNIS is the standardization document for the LunaNet

ESA’s plan

ESA’s plan

⇒launch in Q4 2025

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ESA’s plan

6

ESA’s plan

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NASA’s plan

Initial Capability for LCRNS▪ IOC phase will begin late 2025 with IOC-Alpha
with a minimum of one Augmented Forward Signal(AFS) broadcast over the South Pole region.
▪ IOC-Bravo is expected by 2027 with a minimumof two AFS over the same South Pole region.
▪ Service continues over an expanded South Pole
volume with IOC-Charlie broadcasting a minimumof four AFS, also meeting a requirement for GDOP
for a limited portion of an Earth day.
▪ The LCRNS AFS will comply with the LunaNet
Interoperability Specification.
▪ LCRNS orbit(s) will be defined by the service
provider and are expected to meet the Signal-inSpace-Error.
Rorbe▪ It is expected that LCRNS will be capable ofproviding two-way measurements from Peer-toPeer signals.
▪ Service delivery is reliant on defined lunar
geodetic system and lunar time.

tSweeney_AI88

JAXA’s plan

LNSS is GPS-like satellite constellation for the Moon designed by JAXA

Target:South Poleregion

LNSS satellite
also functioning
as a data relay
satellite to theearth

LNSS satellite
broadcasting oneway navigation
signal9

JAXA’s plan

LNSS contribution towards the establishment of Moon GNSS (LANS)※ ESA Moonlight and NASA LCRNS orbits are notional in figures below
In 2031 and laterIn 2028

Our first navigation
satellite will be deployedin the ELFO. The LNSS andLANS IOC accuracy will beboth evaluated

Our second LNSS Com&Nav
satellite will perform theoptical communication
experiment between Moon
and Earth10

JAXA’s plan
GNSS navigation (real-time OD) for LNSS satellites, making the lunar PNT autonomous

GNSS satellites

Cis-lunar
space

JAXA LNSS
satellite

weak signal

SISE of about
20m (RMS) after
filter convergence

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LNSS single point positioning (SSP) accuracy for a fixed station at the South PoleOur LNSS was designed
to achieve the high 2D・Average SSP errors:(horizontal) PNT accuracy
3D position 37.7m,
2D position 13.8m,
Vertical 32.8m,
Clock bias 6.6E-08s
Error (m)Time (s)Less than 40m formost of the epochs
12LNSS navigation accuracy for a moving object at the South Pole regionmAssumed movement:
circular movementwith velocity of 3
m/s at south altitudeof 85 degrees

Average 2D positioning ≒ 12.9m

Epoch-wise SPP results

Time (s)Applying sequential measurement filtering (EKF)

Navigation results (SISE vel of about 2cm/s)secm<< 15m 3D positioning accuracy<< 10m 2D positioning accuracy
after filter convergenceTime (s)< 20 ns clock estimation accuracy
after filter convergence

Time (s)13Collaboration with ESA and NASA and
LunaNet Interoperability Specification(LNIS)

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LunaNet Interoperability Specification (LNIS) in which the LANS is defined

The LNIS includes:
・Concept of the LANS, message format of the AFS,
signal frequency, power, etc.
・LANS Initial Operations Capability (IOC) andEnhanced Operations Capability (EOC)・Signal-In-Space-Error (SISE) definition for the
LunaNet Service Providers (LNSPs)
Published by NASA and ESA・Lunar Reference System and Lunar Time System
Standard

Draft Version 5 – August 2023

The JAXA LNSS complies with the LNIS and will be
designed to become interoperable and comparablewith the other LNSPs such as ESA and NASA
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LANS South Pole service coverage and performance volume
Signal-In-Space-Error (SISE) requirement

LANS South
Pole service
coverage

Both SISEs are based on lunar
reference frame and time, which
will be defined in the LNIS
applicable documents called Lunar
Reference System and Lunar TimeSystem Standard17

Plan of LANS interoperability
demonstration mission
targeting in 2028

Launching and deploying our first LNSS satellite and LANS receivers to the moon

JAXA
first LNSS
satellite

JAXA H3rocket

JAXA smalllander called
LEAD carrying
LANS receivers

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Proposing the first-ever ESA-NASA-JAXA LANS interoperability and PNT demonstration
GNSS satellite

JAXA LNSS
satellite

weak signal

LANS receivers andlaser retroreflector
placed at South
Pole region

All broadcast thestandardized AFS
to form LANS

weak signal

ESA Moonlight(LCNS) satellite

NASA LCRNS
satellites
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Proposing the first-ever ESA-NASA-JAXA LANS interoperability and PNT demonstration
GNSS satellite

JAXA LNSSsatellite

weak signal

LANS receivers andlaser retroreflector
placed at South
Pole region

And PNT evaluation
based on precise
position and clock
information of theLANS receivers

weak signal

ESA Moonlight(LCNS) satellite

NASA LCRNS
satellites
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LANS interoperability and PNT demonstration – concept of operation
 Three major steps for the demonstration
1.

Mission data acquisition in Moon environment

2.

Ground-truth data calculation by Earth stations

3.

SISE and PNT evaluation by comparing the mission data with the ground-truth dataMoon

2. Ground-truth
data calculation

GNSS satellites(GPS, Galileo, QZSS)

1. Mission dataacquisition
3. PNT evaluation

3. SISE evaluation
EarthLANS satellites(NASA LCRNS, ESA LCNS, JAXA LNSS)
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Mission data acquisition and ground-truth data calculation
Weak signals

GNSS
Earth stations

LANS satellites(NASA LCRNS, ESA LCNS, JAXA LNSS)

Data downlink
LANS satellites(NASA LCRNS, ESA LCNS, JAXA LNSS)

X-band ranging,DDORAFSs

Data downlink

Earth stations

Surface receiver asset※data transmission via JAXA lander

GNSS weak signal and LANS AFSacquisition in actual Moon environment

Earth stations
X-band ranging,DDOR, laser ranging
Surface receiver asset※Laser retroreflector (LRR) is also placed

Precise satellite orbit, receiver position, andclock determination using earth stations

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SISE and PNT evaluation
 The SISE evaluation procedure①

Calculate true pseudo ranges based on the ground-truth data and compare them with the actual
pseudo ranges to evaluate unknown error caused by hardware and moon environmental delays②

Evaluate errors in the satellite ephemerides (orbit and clock prediction errors) by comparing theephemerides with the ground-truth data③

The SISE is assessed by adding the ephemeris error and the identified unknown error, based on
which the moon surface positioning accuracy is evaluated by multiplying with the LANS DOPs
Moon
2. Ground-truth
data calculation

GNSS satellites(GPS, Galileo, QZSS)

1. Mission data acquisition

3. PNT evaluation by comparing
with the ground-truth receiver data

3. SISE evaluation
EarthLANS satellites(NASA LCRNS, ESA LCNS, JAXA LNSS)

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International lunar PNT activities

International Organizations Currently Involved in Lunar PNTLunaNet Interoperability
Specification
development

Lunar PNT/GNSS
interoperability,compatibility, availability

Reference system andtime systemrecommendations

LNIS
WG

Space agency lunar PNT
governance coordination

Space frequency
coordination

Exploration mission roadmaps
and performance needs

26This year’s ICG (International Committee on GNSS) just concluded

・Lunar PNT presentations were made by NASA, ESA, JAXA, China, and India. As of now,these five countries seem the active lunar PNT system developers
・Joint statement on encouraging interoperability and compatibility among the respective
lunar PNT systems adopted
・Recommendation on holding joint ICG-IOAG multilateral workshop on cislunar PNTadopted. JAXA will show a key role in the workshop organization and planning27

まとめ・欧米が月測位を牽引する中、JAXAもLNSSの検討を進めており、欧米日の共同で月版GNSSに相当するLANSを構築する予定である。LANSの定義やAFSの仕様はLNISに記載されており、現在Version 5の制定に向けた作業が国際的に進んでいる

・JAXAはLANSの相互運用性・月測位の実証ミッションを2028年に実施することで検討を進めており、ESA・NASAとの共同実証を目指して調整を進めている。ESA・
NASAとの共同で本実証を成功させることにより、2030年代以降にさらに活発になる国際的な月測位の枠組みに貢献していく
・本実証ミッションでは月の南極域に設置するLANS受信機の精密位置決定のためにLaser retroreflectorも設置する計画である。このレーザーレンジングのデータは月の座標系であるLunar Reference System（LRS）の高精度化といった国際貢献にも資するものである
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