DOI: 10.5066/p14ksanw
title: Lunar Grid Reference System (LGRS) Terrestrial Navigational Training Grids in Artemis Condensed Coordinate (ACC) Format

description: USGS is assessing the feasibility of map projections and grid systems for lunar surface operations. We propose developing a new Lunar Transverse Mercator (LTM), the Lunar Polar Stereographic (LPS), and the Lunar Grid Reference Systems (LGRS). We have also designed additional grids to meet NASA requirements for astronaut navigation, referred to as LGRS in Artemis Condensed Coordinates (ACC). This data release includes LGRS grids finer than 25km (1km, 100m, and 10m) in ACC format for a small number of terrestrial analog sites of interest. The grids contained in this data release are projected in the terrestrial Universal Transverse Mercator (UTM) Projected Coordinate Reference System (PCRS) using the World Geodetic System of 1984 (WGS84) as its reference datum.
 
A small number of geotiffs are provided to relate the linear distortion the UTM and WGS84 systems impose on the analog sites including 1) a clipped USGS Nation Elevation Dataset (NED) Digital Elevation Model (DEM); 2) the grid scale factor of the UTM zone the data is projected in, 3) the height factor based on the USGS NED DEM, 4) the combined factor, and 5) linear distortion calculated in parts-per-million (PPM). Geotiffs are projected from WGS84 in a UTM PCRS zone. Distortion calculations are based on the methods State Plane Coordinate System of 2022. See Dennis (2021; https://www.fig.net/resources/proceedings/fig_proceedings/fig2023/papers/cinema03/CINEMA03_dennis_12044.pdf) for more information.
 
Coarser grids, (>=25km) such as the lunar LTM, LPS, and LGRS grids are not released here but may be acceded from https://doi.org/10.5066/P13YPWQD and displayed using a lunar datum. LTM, LPS, and LGRS are similar in design and use to the Universal Transverse Mercator (UTM), Universal Polar Stereographic (LPS), and Military Grid Reference System (MGRS), but adhere to NASA requirements. LGRS ACC format is similar in design and structure to historic Army Mapping Service Apollo orthotopophoto charts for navigation.
 
Terrestrial Locations and associated LGRS ACC Grids and Files:
 

Projection
	
Location
		
Files




UTM 11N
	
Yucca Flat
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff




UTM 12N
	
Buffalo Park
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff


Cinder Lake
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff


JETT3 Arizona
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff


JETT5 Arizona
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff


Meteor Crater
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff




UTM 13N
	
HAATS
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
1km Grid Shapefile Derby LZ Clip
100m Grid Shapefile Derby LZ Clip
10m Grid Shapefile Derby LZ Clip
1km Grid Shapefile Eagle County Regional Airport KEGE Clip
100m Grid Shapefile Eagle County Regional Airport KEGE Clip
10m Grid Shapefile Eagle County Regional Airport KEGE Clip
1km Grid Shapefile Windy Point LZ Clip
100m Grid Shapefile Windy Point LZ Clip
10m Grid Shapefile Windy Point LZ Clip
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff




UTM 15N
	
Johnson Space Center
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff




UTM 28N
	
JETT2 Icelandic Highlands
		
1km Grid Shapefile
100m Grid Shapefile
10m Grid Shapefile
USGS 1/3" DEM Geotiff
UTM Projection Scale Factor Geotiff
Map Height Factor Geotiff
Map Combined Factor Geotiff
Map Linear Distortion Geotiff





 
The shapefiles and rasters utilize UTM projections. For GIS utilization of grid shapefiles projected in Lunar Latitude and Longitude should utilize a registered PCRS. To select the correct UTM EPSG code, determine the zone based on longitude (zones are 6° wide, numbered 1–60 from 180°W) and hemisphere (Northern Hemisphere uses EPSG:326XX; Southern Hemisphere uses EPSG:327XX), where XX is the zone number. For display in display in latitude and longitude, select a correct WGS84 EPSG code, such as EPSG:4326.
 
Note:
The Lunar Transverse Mercator (LTM) projection system is a globalized set of lunar map projections that divides the Moon into zones to provide a uniform coordinate system for accurate spatial representation. It uses a Transverse Mercator projection, which maps the Moon into 45 transverse Mercator strips, each 8°, longitude, wide. These Transverse Mercator strips are subdivided at the lunar equator for a total of 90 zones. Forty-five in the northern hemisphere and forty-five in the south. LTM specifies a topocentric, rectangular, coordinate system (easting and northing coordinates) for spatial referencing. This projection is commonly used in GIS and surveying for its ability to represent large areas with high positional accuracy while maintaining consistent scale.
 
The Lunar Polar Stereographic (LPS) projection system contains projection specifications for the Moon’s polar regions. It uses a polar stereographic projection, which maps the polar regions onto an azimuthal plane. The LPS system contains 2 zones, each zone is located at the northern and southern poles and is referred to as the LPS northern or LPS southern zone. LPS, like its equatorial counterpart LTM, specifies a topocentric, rectangular, coordinate system (easting and northing coordinates) for spatial referencing. This projection is commonly used in GIS and surveying for its ability to represent large polar areas with high positional accuracy while maintaining consistent scale across the map region.
 
LGRS is a globalized grid system for lunar navigation supported by the LTM and LPS projections. LGRS provides an alphanumeric grid coordinate structure for both the LTM and LPS systems. This labeling structure is utilized similarly to MGRS. LGRS defines a global area grid based on latitude and longitude and a 25×25 km grid based on LTM and LPS coordinate values. Two implementations of LGRS are used as polar areas require an LPS projection and equatorial areas a Transverse Mercator. We describe the differences in the techniques and methods reported in this data release. Request McClernan et. al. (in-press) for more information. ACC is a method of simplifying LGRS coordinates and is similar in use to the Army Mapping Service Apollo orthotopophoto charts for navigation. These grids are designed to condense a full LGRS coordinate to a relative coordinate of 6 characters in length.
 
LGRS in ACC format is completed by imposing a 1km grid within the LGRS 25km grid, then truncating the grid precision to 10m. To me the character limit, a coordinate is reported as a relative value to the lower-left corner of the 25km LGRS zone without the zone information; However, zone information can be reported. As implemented, and 25km^2 area on the lunar surface will have a set of a unique set of ACC coordinates to report locations The shape files provided in this data release are projected in the LTM or LPS PCRSs and must utilize these projections to be dimensioned correctly.