urn:nasa:pds:mgs-rss:data-sha:jgm85h02 1.0 1.22.0.0 Product_Observational 2025 MGS RSS This file contains coefficients and related data for the spherical harmonic model MGS85H2 of the Mars gravity field. MGS85H2 is a 85x85 spherical harmonics model with power rule constraints applied to harmonics above degree 59. It was derived from radio tracking of the Mars Global Surveyor, Odyssey, Pathfinder and Viking 1 Lander spacecrafts. The data cover 1998-03-28T00:00:00.000Z to 2002-04-14T14:00:00.000Z. William Sjogren 1 Jet Propulsion Laboratory https://ror.org/027k65916 2025-02-26 1.0 This product, JGM85H02.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. 1998-03-28T00:00:00.000Z 2002-04-14T14:00:00.000Z 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 2001 Mars Odyssey Host urn:nasa:pds:context:instrument_host:spacecraft.ody is_instrument_host Mars Pathfinder Lander Host urn:nasa:pds:context:instrument_host:spacecraft.mpfl is_instrument_host Viking Lander 1 Host urn:nasa:pds:context:instrument_host:spacecraft.vl1 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:ody.rss is_instrument Radio Science Subsystem (RSS) Instrument urn:nasa:pds:context:instrument:rss.mpfl is_instrument Radio Science Subsystem (RSS) Instrument urn:nasa:pds:context:instrument:rss.vo1 is_instrument Mars Planet urn:nasa:pds:context:target:planet.mars data_to_target 202 13857 10.1126/science.278.5344.1749 W. M. Folkner et al.,Interior Structure and Seasonal Mass Redistribution of Mars from Radio Tracking of Mars Pathfinder. Science 278,1749-1752(1997). The Mars-fixed reference frame is similar to the Pathfinder Mars orientation model but with the prime meridian being consistent with the IAU 2000 coordinate frame. The rotation from the body-fixed position rBF to the inertial postion rIN is: rIN = Rz(-N) Rx(-J) Rz(-PSI) Rx(-I) Rz(-PHI) rBF where N is the angle in the plane of the Earth-mean-equator of J2000 (EME2000) from the vernal equinox (intersection of the mean ecliptic and EME2000 planes) to the intersection of the Mars-mean-orbit of J2000 and EME2000 planes; J is the inclination of the Mars-mean-orbit plane relative to the EME2000 plane; PSI is the angle in the Mars-mean-orbit plane from the intersection of the EME2000 and Mars-mean-orbit planes to the intersection of the Mars-mean-orbit and Mars-true-equator of date planes; I is the inclination of the Mars-true-equator relative to the Mars-mean-orbit plane; PHI is the angle in the plane of the Mars-true-equator from the intersection of the Mars-mean-orbit plane and Mars-true-equator to the Mars prime meridian. PSI, I, and PHI have J2000 epoch and secular values plus corrections for nuations. PHI in addition has seasonal corrections for spin with values similar to Folkner et al., Science 278, 1997. For example, PSI = PSI(t=J2000) + (dPSI/dt)*T + dPSI(nutations) where T is time past J2000 in days. For MGS85H2, the values of the orientation angles are: N = 3.37919183 deg J = 24.67682669 deg PSI(t=J2000) = 81.9683148717 deg dPSI/dt = -0.000005781 deg/day (precession rate of Mars) I(t=J2000) = 25.1894070110 deg dI/dt = 0.000000007 deg/day PHI(t=J2000) = 133.38469 deg dPHI/dt = 350.891985267 deg/day 10.1029/JB084iB11p06231 Reasenberg, R. D., and R. W. King, The rotation of Mars, J. Geophys. Res., 84(B11), 6231-6240 (1979). Note N, J, and the nutation corrections are fixed values and PHI(t=J2000) was chosen to match the prime meridian of the IAU 2000 system. The other orientation values above were estimated when solving for the gravity field. 10.1126/science.1079645 C. F. Yoder et al., Fluid Core Size of Mars from Detection of the Solar Tide. Science 300, 299-303(2003). The k2 Love number to use with this MGS85H2 solution is 0.168. The second degree harmonic coefficients do not include the permanent tide due to the Love number. This delivery is the Mars static gravity field. However, the gravity field varies due to the mass exchange between the polar caps and the Mars atmosphere. The major component of this effect can be included in the gravity field by adding the following correction to the normalized J3 gravity coefficient: dJ3 = 2.474D-09 * sin W*(t-t0) where W is the Mars mean motion = 191.39 deg/yr and t-t0 = years past Jan 1, 1999. MGS-M-RSS-5-SDP-V1.0:JGM85H02.SHA:JGM85H02.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. JGM85H02.SHA 2002-11-08T12:15:18 456524 9c8f27641121ef055323f7a49b49e1b0 MGS Spherical Harmonic ASCII MGS85H2 Model Header 1998-03-28 - 2002-04-14 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 MGS85H2 Model Coefficients Table 1998-03-28 - 2002-04-14 244 456280 PDS DSV 1 The Mars System GM (Mars+Phobs+Deimos) = 42828.3752203 km^3/sec^2 The GM of Mars = 42828.374440 km^3/sec^2 The GM of Phobos = 7.13x10^-4 km^3/sec^2 The GM of Deimos = 6.7x10^-5 km^3/sec^2 Derived Radio Tracking of the MGS, Odyssey, Pathfinder and Viking Lander: MGS Science Phasing Orbit 1 (SPO1) 1998-03-28 to 1998-04-28 Science Phasing Orbit 2 (SPO2) 1998-06-04 to 1998-09-23 Gravity Calibration Orbit (GCO) and Fixed High-Gain Antenna Mapping (FHGA) 1999-02-02 to 1999-03-29 Mapping (MAP) 1999-03-29 to 2002-04-14 Odyssey Transition Orbit (ODYT) 2002-01-11 to 2002-01-15 Pathfinder 1997-07-04 to 1997-10-07 Viking 1 Lander 1976-07-21 to 1982-11-13 The radio tracking data (Doppler and range) blocks consist of: MGS SPO1 and SPO2 at 177 km periapsis with 133,624 observations; MGS GCO at 370 km periapsis with 144,810 observations; MGS MAP at 370 km periapsis with 3,146,564 observations. Odyssey transistion at 200 km periapsis with 27,661 observations. Pathfinder on the Mars surface with 7,562 observations. Viking 1 Lander on the Mars surface with 15,628 observations. The data weights for each block have accounted for the SPO1 and SPO2 Doppler being corrupted by solar plasma while at small Sun-Earth-probe angles. The GCO and MAP data are the highest quality data having a 2-way Doppler data weight near 0.03 mm/sec for a 10 second sample. The Pathfinder Doppler is weighted about 0.08 mm/s and Viking Lander data is weighted near 0.4 mm/s. 3740 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.