urn:nasa:pds:mgs_mola_topography_derived:data_shadr:gtm090aa 1.0 1.23.0.0 Product_Observational 2000 This file contains coefficients and related data for a spherical harmonic model of the shape of Mars. Input data are from the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor (MGS) spacecraft. Producer Greg Neumann Goddard Space Flight Center, MOLA Team DataCurator Madison N. Hughes Washtington University in St. Louis 2026-08-25 1.0 Initial PDS4 version 1997-09-15T19:10:00.000Z 1999-12-31T23:59:59.000Z Mars Global Surveyor Mission urn:nasa:pds:context:investigation:mission.mars_global_surveyor data_to_investigation MOLA MARS GLOBAL SURVEYOR Host urn:nasa:pds:context:instrument_host:spacecraft.mgs is_instrument_host MARS ORBITER LASER ALTIMETER for MGS Instrument urn:nasa:pds:context:instrument:mgs.mola is_instrument Mars Planet urn:nasa:pds:context:target:planet.mars data_to_target gtm090aa.sha 2000-11-16T00:00:00 This file contains coefficients and related data for a spherical harmonic model of the shape of Mars. Input data are from the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor (MGS) spacecraft. Coordinate system is IAU 1991 (Davies et al., Celestial Mechanics and Dynamical Astronomy, 53, 377-397, 1992), areocentric, with longitudes measured positive east. When evaluated, the model gives absolute radius from Mars center of mass in meters. The model is a numerical transform of planetary radius values from the MOLA 0.5-degree gridded data set DATA_SET_ID = 'MGS-M-MOLA-5-IEGDR-L3-V2.0' PRODUCT_ID = 'MOLA-IEG0062R.IMG' into spherical harmonics using Simpson's Rule quadrature. The gridded data set included all MOLA nadir observations from the Orbit Insertion phase, plus Mapping Phase nadir observations from the beginning of mapping through the end of December 1999. Additionally, off-nadir observations of the north pole were included from 87 N latitude and northward, taken during the spring of 1998, and of both poles taken in July of 1999, from 87 N and S to the poles. Orbits 355 and 358 of the Orbit Insertion Phase and parts of orbits 10709 through 10716, inclusive, of the Mapping Phase were excluded because solutions for these orbits were deemed to be poor. (Note: subtract 10000 from a MOLA mapping phase orbit number to determine the equivalent MGS Project orbit number.) Also excluded were shots more than 1 degree off-nadir except as noted above), channel 4 returns, and any returns not classified as ground returns, e.g. clouds or noise, according to the SHOT_CLASSIFICATION_CODE. A total of approximately 123 million observations are represented. Further improvements to the model are expected as additional MGS data are incorporated. This product is a set of two ASCII tables: a header table and a coefficients table. Definitions of the tables follow. This Mars topography model was produced under the direction of D.E. Smith of the MGS MOLA Team. shadr_header_table 0 1 The SHADR header includes descriptive information about the spherical harmonic coefficients which follow in SHADR_COEFFICIENTS_TABLE. The header consists of a single record of eight (delimited) data columns requiring 137 bytes, a pad of 105 unspecified ASCII characters, an ASCII carriage-return, and an ASCII line-feed. Carriage-Return Line-Feed 8 0 244 reference radius 1 ASCII_Real 23 kilometer A nominal value for the equatorial radius. The model gives absolute radius directly, so REFERENCE RADIUS is not needed when using the model. constant 25 ASCII_Real 23 For a gravity field model the assumed gravitational constant GM in km cubed per seconds squared for the planet. For a topography model, set to 1. uncertainty in constant 49 ASCII_Real 23 For a gravity field model the uncertainty in the gravitational constant GM in km cubed per seconds squared for the planet (or, set to 0 if not known). For a topography model, set to 0. degree of field 73 ASCII_Integer 5 Degree of the model field. order of field 79 ASCII_Integer 5 Order of the model field. normalization state 85 ASCII_Integer 5 The normalization indicator. For gravity field: 0 coefficients are unnormalized 1 coefficients are normalized 2 other. reference longitude 91 ASCII_Real 23 degree The reference longitude for the spherical harmonic expansion; normally 0. reference latitude 115 ASCII_Real 23 degree The reference latitude for the spherical harmonic expansion; normally 0. shadr_coefficients_table 244 4186 The SHADR coefficients table contains the coefficients for the spherical harmonic model. Each row in the table contains the degree index m, the order index n, the coefficients Cmn and Smn, and the uncertainties in Cmn and Smn. The (delimited) data require 107 ASCII characters; these are followed by a pad of 13 unspecified ASCII characters, an ASCII carriage-return, and an ASCII line-feed. When evaluated, the model gives absolute radius from Mars center of mass in meters. Carriage-Return Line-Feed 6 0 122 COEFFICIENT DEGREE 1 ASCII_Integer 5 The degree index m of the C and S coefficients in this record. COEFFICIENT ORDER 7 ASCII_Integer 5 The order index n of the C and S coefficients in this record. C 13 ASCII_Real 23 The coefficient Cmn for this spherical harmonic model. S 37 ASCII_Real 23 The coefficient Smn for this spherical harmonic model. C UNCERTAINTY 61 ASCII_Real 23 The uncertainty in the coefficient Cmn for this spherical harmonic model. S UNCERTAINTY 85 ASCII_Real 23 The uncertainty in the coefficient Smn for this spherical harmonic model. gtm090aa.lbl 0 PDS3 Original PDS3 label. Carriage-Return Line-Feed