urn:nasa:pds:mgs-rss:data-sha:jgm75b01 1.0 1.22.0.0 Product_Observational 2025 MGS RSS This file contains coefficients and related data for the spherical harmonic model MGS75B of the Mars gravity field. MGS75B is a 75x75 spherical harmonics model with power rule constraints applied to harmonics above degree 45. It was derived from radio tracking of the Viking 1 Orbiter, Viking 2 Orbiter, and Mars Global Surveyor spacecraft. The Mars-fixed reference frame is given by the IAU 1991 constants. The data cover 1998-03-28T00:00:00Z to 1999-03-29T05:30:00Z. William Sjogren 1 Jet Propulsion Laboratory https://ror.org/027k65916 2025-02-25 1.0 This product, JGM75B01.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. 1998-03-28T00:00:00Z 1999-03-29T05:30:00Z 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 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.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 202 1930 urn:nasa:pds:mgs-rss:data-maps:jgd75b50::1.0 data_to_derived_product urn:nasa:pds:mgs-rss:data-maps:jod75b50::1.0 data_to_derived_product MGS-M-RSS-5-SDP-V1.0:JGM75B01.SHA:JGM75B01.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. JGM75B01.SHA 1999-10-22T11:29:36 357094 7aad3693877c6c6ee12436563bcdca7b MGS Spherical Harmonic ASCII MGS75B Model Header 1998-03-28 - 1999-03-29 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 MGS75B Model Coefficients Table 1998-03-28 - 1999-03-29 244 356850 PDS DSV 1 Derived Radio Tracking of the Viking Orbiter 1, Viking Orbiter 2, and Mars Global Surveyor spacecraft: Viking Orbiter 1 1977-03-11 to 1978-12-22 Viking Orbiter 2 1976-08-07 to 1977-10-23 1977-10-23 to 1978-07-23 Mars Global Surveyor 1998-03-28 to 1998-04-24 (SPO-1) 1998-06-04 to 1998-09-23 (SPO-2) 1999-02-02 to 1999-03-29 (GCO) The radio tracking data blocks consist of: Viking 1 at 310 km periapsis with 60622 observations; Viking 2 at 775 km periapsis with 42451 observations; Viking 2 at 300 km periapsis with 36531 observations; MGS SPO-1 and SPO-2 at 177 km periapsis with 133,725 observations; MGS GCO at 370 km periapsis with 125,889 observations. The apriori and data weights for each block have accounted forthe S-band Doppler on Viking being corrupted by space plasma and the SPO-1 and SPO-2 Doppler being corrupted by solar plasma while at small sun-earth-probe angles. The GCO data are the highest quality data having a Doppler data weight of 0.1 mm/sec for a 10 second sample. 2925 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.