Lunar Navigation Satellite System (LNSS) andIts Demonstration Mission
Masaya Murata
Japan Aerospace Exploration Agency
November 14th, 2022

Outline

1. Lunar navigation satellite system (LNSS)
2. Mission and system overview of LNSS
3. Demonstration mission scheduled in 2028
4. Potential collaboration with ESA and NASA
5. Upcoming related lunar programs
6. Conclusions and future works

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Lunar navigation satellite system (LNSS)I GPS-like navigation system for moon designed by JAXA

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Lunar navigation satellite system (LNSS) (cont’d)
I Communication, positioning, navigation, and timing (CPNT)- Radio frequency and optical communication links between themoon surface user, the LNSS satellites, and the earth

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Mission and system overview of LNSS
I Helping our pressurized/exposed rover and EVA mission locate
their own positions in real-time at the lunar South Pole region

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Mission and system overview of LNSS (cont’d)
I LNSS real-time positioning service for the rover

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Mission and system overview of LNSS (cont’d)
I Localization of the rover on moon surface satellite images
taken by, e.g., NASA lunar reconnaissance orbiter (LRO)

7 / 22Requirements of LNSS
I Real-time horizontal positioning accuracy less than 40 meters∗
at the lunar South Pole region at any time
- We need the specific satellite constellation and accurate orbit
and clock determination for the LNSS satellites- Although the nominal operation duration for our pressurized
rover is eight-hour per day, 24 hours (continuous) PNT service
should be kept for contingency cases

I 10 Mbps and more, and hopefully 1 Gbps transmission rate
between the moon and the earth- We use the LNSS satellites as communication relay satellites
using X-band and Ka-band. Optical communication links arealso possible choices∗

may change depending on the NASA’s requirement
8 / 22LNSS satellite constellation
I Eight-satellite constellation with two elliptical lunar frozen
orbits (ELFOs) whose orbital periods are about twelve hours
I This constellation enables high horizontal positioning accuracy
at the South Pole region, as shown in the next few slides

9 / 22LNSS satellite constellation (cont’d)
I Our constellation achieves the low horizontal dilution ofprecision (HDOP) at the lunar South Pole at any time
- For reference, the HDOP of the GPS at the Tsukuba spacecenter in Japan was about 1.2

I We aim for the HDOP of 1.3 and the SISRE of less than 30
meters to meet our positioning accuracy requirement

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Orbit and clock estimation of LNSS satellites
I GNSS navigation using the weak navigation signals

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Orbit and clock estimation of LNSS satellites
I The following graph shows the expected GPS navigation
accuracy for the eight LNSS satellites with space-borne
rubidium atomic clock frequency standard (RAFS) clocks- Each color represents each satellite. The RMSEs after the filter
convergences were 16.5 (orbit) and 1.4 (clock bias) meters

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Communications of LNSS
I Requirement: 10 Mbps and more, and hopefully 1 Gbps
transmission rate between the moon and the earth- 10 Mbps to 1 Gbps from the moon surface to the earth formission data transmission- We use the LNSS satellites as communication relay satellites
using X-band, Ka-band, and possibly optical links too

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Demonstration mission scheduled in 2028
I How accurate PNT do we actually achieve on the lunar
surface? Demonstration mission in real moon environment

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Overview of demonstration mission
I One LNSS satellite and a receiver will be deployed in theELFO and at the South Pole region, respectively
I These satellite and receiver will be launched and delivered tothe moon environment by our rocket and lander

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JAXA proposal for collaboration
I Collaboration with the NASA’s lunar communications relay
and navigation systems (LCRNS) and the ESA’s Moonlight toprove our PNT capability on the lunar surface

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JAXA proposal for collaboration (cont’d)
I We will deploy one LNSS satellite in our ELFO that minimizes
the HDOP at the South Pole region of the collaborative
constellation with the ESA and the NASA

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Proposal of IOC for early Artemis programs
I Artemis surface elements need PNT service as early as
possible. We propose to develop a collaborative constellation
with ESA and NASA for the initial operating capability (IOC)I E.g., there will be at least one LNSS satellite, four Moonlightsatellites, and LCRNS satellites, according to their timelines

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Upcoming related lunar programs
I November 16th, 2022: US Artemis 1
I 2024: NASA Lunar GNSS Receiver Experiment (LuGRE)- GNSS acquisition, navigation, and orbit determination
experiments in cis-lunar and moon environment

I 2024: US Artemis 2I 2024∼: NASA’s LCRNS Initial Operating Capability (IOC)- Providing communication and PNT for moon

I 2025: ESA Lunar Pathfinder- GNSS acquisition, navigation, orbit determination, andcommunication experiments in the ELFO

I 2025: US Artemis 3 and Lunar Gateway19 / 22Upcoming related lunar programs (cont’d)
I 2027: ESA Moonlight Initial Operating Capability (IOC)- 1 large COMM/NAV satellite and 1 NAV-only satellite

I 2029: ESA Moonlight Full Operating Capability (FOC)- Plus 2 NAV-only satellites (4 NAV satellites in total)

I 2028?: US LunaNet Enhanced Operating Capability (EOC)- Full coverage for entire moon surface

I 2028: LNSS demonstration mission- First-ever lunar PNT experiment at South Pole region inconjunction with ESA and NASAI 2029?: LNSS Initial Operating Capability (IOC)- Collaborative satellite constellation with ESA and NASAI 2031?∼: China’s lunar PNT satellite constellation system- For building International Lunar Research Station (ILRS)
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Lunar PNT interoperability
I The interoperability has been one of the key issues in theGNSS community, which has been successful by theinternational efforts
I The interoperability is also the case for the lunar PNTsystems under planning such as the NASA’s LCRNS, ESA’sMoonlight, and our LNSS
I Thanks to the LunaNet interoperability specification, thenavigation signals of the LCRNS, Moonlight, and LNSS all
become the same
I Interoperability recommendation to the ICG-16 “Coordinationof GNSS and lunar PNT systems for lunar operations”
prepared by WG-B Space Use Subgroup (SUSG) was accepted

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Conclusions and future works
I Mission and system overview of our LNSS are presented
I The demonstration mission is currently scheduled in 2028 forwhich JAXA proposes to collaborate with ESA and NASA
I Investigation ongoing on the collaborative constellation,
LNSS-based lander navigation, and feasibility of reference
station at South Pole region
I Combined navigation using LNSS, IMU, digital elevation map(DEM), image, and altimeter becomes also essential

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