Coordinate System?

A range of disparate coordinate systems were used for planetary data from different missions stored in PDS, which makes it difficult to search and correlate data from various instruments. Currently, all products in ODE are stored in planetocentric, positive longitude east, 0 to 360 degrees coordinates. Tables 2-4 illustrate the original coordinate system used in the PDS archive. ODE uses a variety of methods to obtain a location for different products. Most of the data coordinates stored in ODE are acquired from the attached or detached PDS labels. ODE also has data coordinates acquired from the Unified Planetary Coordinates (UPC) database. The method used for a particular product can be found under the product results page, metadata tab, at the bottom under ODE notes. NOTE: coordinates are for searching and display only and may vary in precision. Users should explore and understand the data set to determine how to precisely map the product.

The UPC project was carried out at the U. S. Geological Survey (USGS) and Jet Propulsion Laboratory (JPL). It provides easy access to planetary data in a set of unified, consistent coordinate systems (Becker et al., 2007), which is also consistent with the MRO and MOLA data.

The Planetocentric system has an origin at the center of mass of the body. The planetocentric latitude is the angle between the equatorial plane and a vector connecting the point of interest and the origin of the coordinate system. Latitudes are defined to be positive in the northern hemisphere of the body, where north is in the direction of Earth's angular momentum vector, i.e., pointing toward the hemisphere north of the solar system invariant plane. Planetocentric longitude is measured around the equator of the body from a prime meridian defined and adopted by international agreement. Longitudes increase toward the east making the Planetocentric system right-handed. Radius is the distance from the planetary body’s center of mass to the point of interest.

A spheroid usually approximates well to the shape of planets, because the shape of a rotating body in hydrostatic equilibrium is approximately a spheroid. Mapping parameters for different planetary bodies (Mars, Moon, Mercury, and Venus) are listed in Table 1 (Seidelmann et al., 2002; 2005; Davies et al., 1986). The first column gives the mean radius of the body. The standard errors of the mean radii indicate the accuracy of determination of these parameters due to inaccuracies of the observational data. The second and third columns give equatorial and polar radii for 'best-fit' spheroids. An ellipsoid has been adopted for Mars by the IAU with a polar radius of 3376.2 km and an equatorial radius of 3396.19 km. For Moon, Mercury, and Venus, a sphere is used as the reference surface.

Table 1. Mapping Parameters (unit: km)

Planet	Mean Radius	Equatorial Radius	Polar Radius	Standard
Mars	3389.5±0.2	3396.19±0.1	AVG 3376.2±0.1 N 3373.19±0.1 S 3379.21±0.1	IAU2000
Moon	1737.4±1	1737.4±1	1737.4±1	IAU2000
Mercury	2439.7±1.0	2439.7±1.0	2439.7±1.0	IAU2000
Venus	6051.8±1.0	6051.8±1.0	6051.8±1.0	IAU2000
Venus	6051	6051	6051	IAU1985

Most of the basemaps stored in ODE are provided by USGS. Map projection is based on spheres rather than ellipsoids for these basemaps because of the computational cost and the capabilities of commercial software applications. The adopted projection convention for these basemaps includes Equirectangular (also named Simple Cylindrical) and Polar Stereographic map projections. The global maps are in Equirectangular map projections using the planetocentric coordinate system with east positive longitude. Mars, Mercury and Moon used IAU2000 standard, and Venus used IAU1985 standard. The polar maps are stored in polar stereographic projections.

The Equirectangular projection (Snyder, 1987) is typically used at middle and lower latitudes. With this projection, all lines of latitude are parallel to one another, as is also the case with longitude lines. Parallels of latitude and meridians of longitude are straight lines that are perpendicular to one another. This map projection is centered on the equator. The map resolution is constant throughout the image. The Polar Stereographic projection (Snyder, 1987), ideal for maps covering the polar regions, minimizes scale and shape distortion at high latitudes. This projection is centered on the north or south pole. Lines of longitude extend radially from the pole, and parallels of latitude are concentric circles around the center. For Mars, the Polar Stereographic projection is approximated by adopting a spherical geometry with a polar radius of 3376.2 km.

More information on how to predefine ArcGIS projection files can be found in the USGS Astrogeology Mapping, Remote-sensing, Cartography, Technology, and Research (MRCTR) GIS Lab website. Projection files can be downloaded from the MRCTR and ODE websites.

Table 2. Reference System Used for Mars Data in Different Missions

Mission	Instrument	Data_Set_ID	Product_Type	Reference System Used in Archive
MRO	CRISM	MRO-M-CRISM-2-EDR-V1.0	EDR	IAU2000 planetocentric reference system with east longitude (0-360ο) being positive
		MRO-M-CRISM-4/6-CDR-V1.0	CDR (contains calibration files used to process EDRs to units of radiance or I/F)
		MRO-M-CRISM-6-DDR-V1.0	DDR
		MRO-M-CRISM-6-LDR-V1.0	LDR
		MRO-M-CRISM-3-RDR-TARGETED-V1.0	TARGETED_RDR (TRDR)
		MRO-M-CRISM-5-RDR-MULTISPECTRAL-V1.0	MAP_PROJECTED_MULTISPECTRAL_RDR (MRDR)
		MRO-M-CRISM-5-RDR-MPTARGETED-V1.0	MTRDR (not available yet)
	CTX	MRO-M-CTX-2-EDR-L0-V1.0	EDR	Image coordinates (Lat, Lon) were computed using NAIF SPICE kernel by MSSS personnel or NAIF
	MARCI	MRO-M-MARCI-2-EDR-L0-V1.0	EDR	Using NAIF SPICE kernel
	HIRISE	MRO-M-HIRISE-2-EDR-V1.0	EDR	N/A
		MRO-M-HIRISE-3-RDR-V1.0	RDR (without the embedded map projection information)	IAU2000 planetocentric
		MRO-M-HIRISE-3-RDR-V1.1	RDRV11 (with the embedded map projection information)
		MRO-M-HIRISE-5-DTM-V1.0	DTM
	MCS	MRO-M-MCS-2-EDR-V1.0	EDR	IAU2000 planetocentric
		MRO-M-MCS-4-RDR-V1.0	RDR	Planetocentric spherical coordinates
		MRO-M-MCS-5-DDR-V1.0	DDR (TBD)	Planetocentric spherical coordinates
	RSS	MRO-M-RSS-1-MAGR-V1.0	EDR	SPK and CKF files can be converted to a wide range of coordinate frames by the NAIF reader routines. Other data types are not dependent on definition of a coordinate system.
		MRO-M-RSS-5-SDP-V1.0	RSDMAP	IAU2000 planetocentric
		MRO-M-RSS-5-SDP-V1.0	SHADR
		MRO-M-RSS-5-SDP-V1.0	SHBDR
	SHARAD	MRO-M-SHARAD-3-EDR-V1.0	EDR	IAU2000 planetocentric reference ellipsoid
	SHARAD	MRO-M-SHARAD-4-RDR-V1.0	RDR	IAU2000 planetocentric reference ellipsoid
Mars Express (MEX)	HRSC	MEX-M-HRSC-3-RDR-V2.0	RDR	Using SPICE kernel
		MEX-M-HRSC-5-REFDR-MAPPROJECTED-V2.0	REFDR (map projected image data)	Planetographic spherical coordinates with east longitude being positive (r = 3396.0 km)
		MEX-M-HRSC-5-REFDR-DTM-V1.0	REFDR_DTM	Planetocentric spherical coordinates with east longitude being positive (r = 3396.0 km)
	SPICAM	MEX-Y/M-SPI-2-IREDR-RAWXCRU/MARS-V1.1	EDR	The SPICAM data products are not projected into any coordinate system
		MEX-M-SPI-2-IREDR-RAWXMARS-EXT1-V1.0	EDR
		MEX-M-SPI-2-IREDR-RAWXMARS-EXT2-V1.0	EDR
		MEX-M-SPI-2-IREDR-RAWXMARS-EXT3-V1.0	EDR
		MEX-Y/M-SPI-2-UVEDR-RAWXCRU/MARS-V1.1	EDR
		MEX-M-SPI-2-UVEDR-RAWXMARS-EXT1-V1.0	EDR
		MEX-M-SPI-2-UVEDR-RAWXMARS-EXT2-V1.0	EDR
		MEX-M-SPI-2-UVEDR-RAWXMARS-EXT3-V1.0	EDR
	MaRS	MEX-M-MRS-1/2/3-NEV-0001-V1.0	Raw data	N/A
		MEX-M-MRS-1/2/3-EXT1-0736-V1.0	RDR	N/A
		MEX-M-MRS-1/2/3-EXT2-1334-V1.0	RDR	N/A
		MEX-M-MRS-5-OCC-9101-V2.0	Reduced occultation data	Planetocentric coordinates
	MARSIS	MEX-M-MARSIS-2-EDR-V1.0	EDR	Planetocentric coordinates
		MEX-M-MARSIS-2-EDR-EXT1-V1.0	EDR	Planetocentric coordinates
		MEX-M-MARSIS-3-RDR-SS-V1.0	RDR (MEX MARS MARSIS REDUCED DATA RECORD SUBSURFACE V1.0)	Planetocentric coordinates
		MEX-M-MARSIS-3-RDR-AIS-V1.0	RDR (MEX MARS MARSIS RDR ACTIVE IONOSPHERE SOUNDING V1.0	Measurements of wave electric fields, which are presented as detected by the sensors and are not rotated into any other coordinate system.
		MEX-M-MARSIS-3-RDR-AIS-EXT1-V1.0	RDR
		MEX-M-MARSIS-3-RDR-AIS-EXT2-V1.0	RDR
		MEX-M-MARSIS-3-RDR-AIS-EXT3-V1.0	RDR
	OMEGA	MEX-M-OMEGA-2-EDR-FLIGHT-V1.0	EDR	IAU2000 planetocentric
		MEX-M-OMEGA-2-EDR-FLIGHT-EXT1-V1.0	EDR
		MEX-M-OMEGA-2-EDR-FLIGHT-EXT2-V1.0	EDR
	PFS	MEX-M-PFS-2-EDR-NOMINAL-V1.0	EDR	planetocentric coordinates system
		MEX-M-PFS-2-EDR-EXT1-V1.0	EDR
		MEX-M-PFS-2-EDR-EXT2-V1.0	EDR
		MEX-M-PFS-2-EDR-EXT3-V1.0	EDR
Mars Odyssey	GRS	ODY-M-GRS-2-EDR-V1.0	EDR	IAU2000 planetocentric
		ODY-M-GRS-5-AHD-V1.0	AVERAGED_HEND_DATA (AHD)
		ODY-M-GRS-5-AND-V1.0	AVERAGED_NEUTRON_DATA (AND)
		ODY-M-GRS-5-SGS-V1.0	SUMMED_GAMMA_SPECTRA (SGS)
		ODY-M-GRS-4-DHD-V1.0	DERIVED_HEND_DATA (DHD)
		ODY-M-GRS-4-DND-V1.0	DERIVED_NEUTRON_DATA (DND)
		ODY-M-GRS-4-CGS-V1.0	CORRECTED_GAMMA_SPECTRA (CGS)
		ODY-M-GRS-5-ELEMENTS-V1.0	ELEMTS - Element Concentrations	N/A
	THEMIS		VIS-EDR; IR-EDR; VIS-RDR; IR-RDR; VIS-ABR; IR-BTR	IAU2000 planetocentric
	MARIE	ODY-M-MAR-2-REDR-RAW-DATA-V1.0	REDRs	MARIE's internal coordinate system is defined by the geometry of the detector. The PSDs have their own coordinate system in the sense that each strip (corresponding to a row or a column) is assigned a sequential number from 1 to 24. These values are not referenced to any other coordinate system, as the primary purpose of the PSDs is to calculate the angle at which incident particles traverse the silicon detectors.
	MARIE	ODY-M-MAR-3-RDR-CALIBRATED-DATA-V1.0	RDRs
	Radio Science	ODY-M-RSS-1-RAW-V1.0	AGK/ion/ODF/opt/sak/sff/soe/spk/tck/tnf/tro/wea	SPK, TCK, and SAK files can be converted to a wide range of coordinate frames by the NAIF reader routines. Other data types are not dependent on definition of a coordinate system.
	Accelerometer	TBD
Mars Global Surveyor (MGS)	MOC-NA / MOC-WA	MGS-M-MOC-NA/WA-2-DSDP-L0-V1.0	NADSDP / WADSDP	IAU1994 planetographic reference system (re = 3397.0 km; rp = 3375.0 km)
	MOC-NA / MOC-WA	MGS-M-MOC-NA/WA-2-SDP-L0-V1.0	NASDP / WASDP
	MOLA	MGS-M-MOLA-3-PEDR-L1A-V1.0	PEDR	IAU2000 planetocentric (r = 3396.0 km)
		MGS-M-MOLA-5-MEGDR-L3-V1.0	MEGDR - Mission Experiment Gridded Data Record	IAU2000 planetocentric (Davies et al., 1994; Duxbury et al., 2001; Seidelmann et al., 2002)
		MGS-M-MOLA-5-SHADR-V1.0	SHADR	IAU 1991(Davies et al., 1992), planetocentric, with longitudes measured positive east.
		MGS-M-MOLA-3-PRDR-L1A-V1.0	PRDR	IAU2000 planetocentric

Note

CRISM: Compact Reconnaissance Imaging Spectrometers for Mars
CTX: Context Camera
GRS: Gamma Ray Spectrometer
HiRISE: High Resolution Imaging Science Experiment
HRSC: High Resolution Stereo Camera
MARCI: Mars Color Imager
MARIE: Martian Radiation Environment Experiment
MARSIS: Mars Advanced Radar for Subsurface and Ionosphere Sounding
MCS: Mars Climate Sounder
MOC: Mars Orbiter Camera
MOLA: Mars Orbiter Laser Altimeter
MRO: Mars Reconnaissance Orbiter
MaRS: Mars Express Orbiter Radio Science
OMEGA: Observatoire Mineralogie, Eau, Glaces, Activite
PFS: Planetary Fourier Spectrometer
RSS: Radio Science Subsystem
SHARAD: Shallow Radar
SPICAM: Spectroscopy for the Investigation of Characteristics of the Atmosphere of Mars
THEMIS: The Thermal Emission Imaging System

Table 3. Reference System Used for Moon Data in Different Missions

Mission	Instrument	Data_Set_ID	Product_Type	Reference System Used in Archive
Clementine	HIRES	CLEM1-L-H-5-DIM-HIRES-V1.0	MDIM	Planetographic spherical coordinates with r = 1737.4 km
	HIRES/LWIR/NIR/UVVIS/A-STAR/B-STAR	CLEM1-L/E/Y-A/B/U/H/L/N-2-EDR-V1.0	EDR	Planetocentric
	UVVIS	CLEM1-L-U-5-DIM-BASEMAP-V1.0	MDIM 5-Band Mosaic	Planetographic spherical coordinates with r = 1737.4 km
	UVVIS	CLEM1-L-U-5-DIM-UVVIS-V1.0	MDIM Global Basemap Mosaic	Planetographic spherical coordinates with r = 1737.4 km
	LIDAR	CLEM1-L-LIDAR-3-TOPO-V1.0	TOPO Raw Data	N/A
	LIDAR	CLEM1-L-LIDAR-5-TOPO-V1.0	TOPO	Planetocentric (Williams et al., 1993; Dickey et al., 1994)
	RSS	CLEM1-L-RSS-1-BSR-V1.0	Raw Data Record	SPK ephemeris files and CK attitude files are produced for the J2000 inertial reference frame. SPICE reader routines may be used to convert these to other coordinate systems. Other data types are not dependent on definition of a coordinate system.
		CLEM1-L-RSS-5-BSR-V1.0	RDR	Planetocentric system with positive east longitude (r = 1737.4 km)
		CLEM1-L-RSS-5-GRAVITY-V1.0	GRAVITY	Planetocentric (Davies et al., 1992)
	LWIR	CLEM1-L-LWIR-3-RDR-V1.0	RDR	Planetocentric
Lunar Prospector (LP)	{GRS, NS, APS, MAG, ER}	LP-L-ENG/GRS/NS/APS/MAG/ER-1-MDR-V1.0	MDR	Selenocentric/selenographic
	GRS	LP-L-GRS-3-RDR-V1.0	RDR	N/A
	NS	LP-L-NS-3-RDR-V1.0	RDR	N/A
	RSS	LP-L-RSS-5-GRAVITY-V1.0	GRAVITY	Planetocentric system with positive east longitude (r = 1738.0 km) (Newhall and Williams, 1997)
	RSS	LP-L-RSS-5-LOS-V1.0	LOS	Planetocentric system (Newhall and Williams, 1997)
	MAG	LP-L-MAG-4-SUMM-LUNARCRDS-5SEC-V1.0	Magnetic field data from LP MAG	in two different coordinate systems: selenocentric solar ecliptic (SSE) and body-fixed selenographic (SEL)
		LP-L-MAG-4-LUNAR-FIELD-TS-V1.0	LP MAG Level 2 Data (CODMAC Level 4): Lunar Magnetic Field Time Series V1.0	in two coordinate systems: selenographic (SG) coordinates; and east, north, and radial (ENR) coordinates
		LP-L-MAG-5-LUNAR-FIELD-BINS-V1.0	LP MAG Level 3 Data (CODMAC Level 5): Lunar Magnetic Field Bins V1.0	Measurements in east, north, and radial (ENR) coordinates
		LP-L-MAG-5-SURFACE-FIELD-MAP-V1.0	LP MAG Level 4 Data (CODMAC Level 5): Surface Magnetic Field Maps V1.0	Selenographic with mean lunar radius (1738 km)
	ER	LP-L-ER-4-SUMM-OMNIDIRELEFLUX-V1.0	low resolution data from LP ER	N/A
		LP-L-ER-3-RDR-HIGHRESFLUX-V1.0	high resolution data from LP ER	N/A
		LP-L-ER-3-RDR-3DELEFLUX-80SEC-V1.0	3-D spectrum data from LP ER	in ''despun spacecraft'' (SCD) coordinates, closely related to GSE coordinates. (https://starbrite.jpl.nasa.gov/pds/viewProfile.jsp?dsid=LP-L-ER-3-RDR-3DELEFLUX-80SEC-V1.0)
		LP-L-ER-4-ELECTRON-DATA-V1.0	LP ER Level 2 Data (CODMAC Level 4)	N/A
LRO	All LRO data products including LROC, LOLA, LAMP GDR, LEND, DIVINER and Mini-RF use a common Lunar Coordinate System unless being specified in the SIS document. See LRO Project and LGCWG White Paper. The planetocentric coordinates were used, which are compatible with the one used within the PDS for Clementine data.
LRO	Exceptions: No coordinate system applicable for data sets: Diviner EDR/PRP, LEND EDR/RDR, LAMP EDR/RDR, Mini-RF CDR, LOLA EDR/SHA, and LROC SDRPHO. See product SIS documents.
ISRO’s Chandrayaan-1	Mini-RF and M3 use the planetocentric coordinate system, which is the same as the LRO instrument.

Note

CRaTER: Cosmic Ray Telescope for the Effects of Radiation
DIVINER: Diviner Lunar Radiometer Experiment
HIRES: High Resolution Camera
LAMP: Lyman-Alpha Mapping Project
LEND: Lunar Exploration Neutron Detector
LGCWG: Lunar Geodesy and Cartography Working Group
LIDAR: Laser Image Detection and Ranging
LOLA: Lunar Orbiter Laser Altimeter
LROC: Lunar Reconnaissance Orbiter Camera
LWIR: Long Wavelength Infrared
M3: Moon Mineralogy Mapper
Mini-RF: Miniaturized Radio Frequency
Mini-SAR: Miniature Synthetic Aperture Radar, also called Forerunner
NIR: Near-Infrared
UVVIS: Ultraviolet/Visible

Table 4. Reference System Used for Mercury Data in Different Missions

Mission	Reference System Used in Archive
MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging)	There are two general coordinate systems in use for the MESSENGER project: • The celestial reference system used for target and spacecraft position and velocity vectors and camera pointing. • The planetary coordinate system for geometry vectors and target location. The celestial coordinate system is J2000 (Mean of Earth equator and equinox of J2000). The planetary coordinate system is planetocentric system with east longitude being positive.

Mission

Reference System Used in Archive

MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging)

There are two general coordinate systems in use for the MESSENGER project:

• The celestial reference system used for target and spacecraft position and velocity vectors and camera pointing.

• The planetary coordinate system for geometry vectors and target location.

The celestial coordinate system is J2000 (Mean of Earth equator and equinox of J2000). The planetary coordinate system is planetocentric system with east longitude being positive.

Table 5. Reference System Used for Venus Data in Different Missions

Mission	Reference System Used in Archive
MESSENGER at Venus	There are two general coordinate systems in use for the MESSENGER project: • The celestial reference system used for target and spacecraft position and velocity vectors and camera pointing. • The planetary coordinate system for geometry vectors and target location. The celestial coordinate system is J2000 (Mean of Earth equator and equinox of J2000). The planetary coordinate system is planetocentric system with east longitude being positive.
Magellan Mission	The ALTIMETRIC AND RADIOMETRIC Global products shall adopt the J2000 coordinate system for all inertial values, i.e. those that define the motion of the spacecraft relative to celestial objects. Locations on the Venus surface shall be expressed in a Venus body-fixed reference frame (Davies et al., 1992B).