urn:nasa:pds:mgs-rss:data-sha:ggm50a01 1.0 1.22.0.0 Product_Observational 2025 MGS RSS This file contains coefficients and related data for the spherical harmonic model Baseline (IAU 1988) of the Mars gravity field. Input data are from radio tracking of the Mariner and Viking spacecrafts. There no data from Mars Global Surveyor in this model, though the model serves as a baseline for future MGS models which will eventually be dominated by MGS. The data cover 1971-11-14T00:00:00Z to 1980-08-07T23:59:59Z. David Smith 1 Goddard Space Flight Center https://ror.org/0171mag52 2025-02-25 1.0 This product, GGM50A01.SHA, was originally released as part of the PDS3 MGS-M-RSS-5-SDP-V1.0 data set. The metadata have been migrated to PDS4. The data themselves are unchanged. 1971-11-14T00:00:00Z 1980-08-07T23:59:59Z Science Derived Mars Global Surveyor Spherical Harmonic Model ASCII Data Mars Global Surveyor Mission urn:nasa:pds:context:investigation:mission.mars_global_surveyor data_to_investigation Mars Global Surveyor Host urn:nasa:pds:context:instrument_host:spacecraft.mgs is_instrument_host Mariner 9 Host urn:nasa:pds:context:instrument_host:spacecraft.mr9 is_instrument_host Viking Orbiter 1 Host urn:nasa:pds:context:instrument_host:spacecraft.vo1 is_instrument_host Viking Orbiter 2 Host urn:nasa:pds:context:instrument_host:spacecraft.vo2 is_instrument_host Radio Science Subsystem (RSS) Instrument urn:nasa:pds:context:instrument:mgs.rss is_instrument Radio Science Subsystem (RSS) Instrument urn:nasa:pds:context:instrument:rss.mr9 is_instrument Radio Science Subsystem (RSS) Instrument urn:nasa:pds:context:instrument:rss.vo1 is_instrument Radio Science Subsystem (RSS) Instrument urn:nasa:pds:context:instrument:rss.vo2 is_instrument Mars Planet urn:nasa:pds:context:target:planet.mars data_to_target 10.1007/BF00051818 Davies, M. E., V. K. Abalakin, A. Brahic, M. Bursa, B.H. Chovitz, J. H. Lieske, P. K. Seidelmann, A. T. Sinclair, Y. S. Tjuflin, Report of the IAU/IAG/COSPAR Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites: 1991, Celestial Mechanics and Dynamical Astronomy, 53, 377-397, 1992. For each arc certain parameters were determined: the spacecraft state (position and velocity), a solar radiation pressure coefficient, Doppler biases for each station over the arc to account for frequency biases, and (for the 300 km periapsis altitude arcs) a drag coefficient was adjusted on each day. The a priori force model that was used included a preliminary gravity solution obtained from the analysis of these data, a 50 x 50 solution designated mgm0340. In addition, third body perturbations were modeled, the solar radiation pressure perturbation was applied, and the appropriate relativistic perturbations in the measurement model, and the force model were included. The JPL DE-96 set of planetary and lunar ephemerides was used in these analyses. The planet orientation model was based on the 1988 IAU system of constants, and a reference radius of 3394.2 km. 10.1007/BF00806341 Lerch, F.J., Optimum Data Weighting and Error Calibration for Estimation of Gravitational Parameters, Bulletin of Geodesy, 65, 44-52, 1991. The input data were weighted at 0.8 to 4.1 cm/s, and the data weights were calibrated using the subset calibration method of [LERCH1991]. Although each data arc was typically fitted to the level of a few mm/s, the data were downweighted in this fashion in order to attenuate the power of the high degree terms, and account for any systematic mismodeling that might still be present in the data. Kaula, W.M., Theory of Satellite Geodesy, Blaisdell, Waltham, MA, 1966. The gravity model was derived using a Kaula type constraint: sqrt(2)*13*10**(-5)/L**2 where L is the spherical harmonic degree. Without this constraint, the high degree terms develop excessive power. MGS-M-RSS-5-SDP-V1.0:GGM50A01.SHA:GGM50A01.SHA data_to_derived_source_product 10.17189/1519757 PDS Planetary Plasma Interactions Node This is the first version converted to PDS4. The DOI references the source PDS3 data set. GGM50A01.SHA 1998-12-22T16:38:24 161650 23935c7a094013c00956b7d30e3482f1 MGS Spherical Harmonic ASCII Baseline (IAU 1988) Model Header 1971-11-14 - 1980-08-07 0 1 Carriage-Return Line-Feed 8 0 244 Reference Radius 1 1 ASCII_Real 23 The assumed reference radius of the spherical planet. Constant 2 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 3 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 4 73 ASCII_Integer 5 deg of the model field. Order of Field 5 79 ASCII_Integer 5 Order of the model field. Normalization State 6 85 ASCII_Integer 5 The normalization indicator. For gravity field: 0 coefficients are unnormalized 1 coefficients are normalized 2 other. Reference Longitude 7 91 ASCII_Real 23 deg The reference longitude for the spherical harmonic expansion; normally 0. Reference Latitude 8 115 ASCII_Real 23 deg The reference latitude for the spherical harmonic expansion; normally 0. MGS Spherical Harmonic ASCII Baseline (IAU 1988) Model Coefficients Table 1971-11-14 - 1980-08-07 244 161406 PDS DSV 1 The model was constructed from 232,323 observations, summarized in the table below. The data were divided into 270 spans or independent arcs (covering 1142 days) based on considerations of data coverage and timing of maneuvers. Spacecraft Periapsis Inclination Number Average Arc Total Altitude of Arcs Length Observations (km) (deg) (days) ---------- --------- ----------- ------- ----------- ------------ Mariner 9 1500 64.4 32 4.3 49878 Viking 1 1500 38.2 29 4.2 31393 Viking 1 300 39.1 95 4.8 63977 Viking 2 1400 55.4 12 3.8 11878 Viking 2 1500 75.1 11 4.7 10467 Viking 2 778 80.1 54 3.8 35375 Viking 2 300 80.2 37 4.2 29355 ---------- ------- ------------ Total 270 232323 1323 Carriage-Return Line-Feed Comma 6 0 Coefficient Degree 1 ASCII_Integer 5 %5d The degree index m of the C and S coefficients in this record. Coefficient Order 2 ASCII_Integer 5 %5d The order index n of the C and S coefficients in this record. C 3 ASCII_Real 23 %23.16e The coefficient Cmn for this spherical harmonic model. S 4 ASCII_Real 23 %23.16e The coefficient Smn for this spherical harmonic model. C Uncertainty 5 ASCII_Real 23 %23.16e The uncertainty in the coefficient Cmn for this spherical harmonic model. S Uncertainty 6 ASCII_Real 23 %23.16e The uncertainty in the coefficient Smn for this spherical harmonic model.