urn:nasa:pds:mess_mla_derived:document_navassmt:mlatrackadjustments 1.0 1.10.1.0 Product_Observational 2017 A summary table of the adjustments made to the spacecraft position using navigation orbits and MLA data. This table contains one record corresponding to each MLA CDR/RDR plot in the document_navassmt collection. 2018-08-09 1.0 PDS4 migrated document 2014-05-26T02:38:29Z 2015-04-30T11:14:16Z MESSENGER Mission urn:nasa:pds:context:investigation:mission.messenger data_to_investigation MESSENGER MESSENGER Spacecraft urn:nasa:pds:context:instrument_host:spacecraft.mess is_instrument_host Mercury Laser Altimeter Instrument urn:nasa:pds:context:instrument:mla.mess is_instrument Mercury Planet urn:nasa:pds:context:target:planet.mercury document_to_target urn:nasa:pds:mess_mla_derived:document_navassmt:navassmt_navinfo data_to_document mlatrackadjustments.tab 2017-01-26 0 2031 This table summarizes all adjustments to spacecraft position made using data from the MLA instrument during the low altitude MESSENGER orbits. Each record represents one adjustment to spacecraft position based on an MLA ground track, an existing MLA Digital Elevation Map, and a predicted SPK provided by the navigation team. The record length is currently set to 142 bytes, with an additional 2 bytes for a carriage return/line feed Carriage-Return Line-Feed 15 0 144 CDR_ID 1 1 ASCII_Integer 10 The ID of the MLA CDR/RDR that was used to evaluate the spacecraft position relative to an existing MLA digital elevation map. NAV_SPK_ID 2 11 ASCII_Real 6 Identifier of the predictive navigation orbit solution used to geolocate the particular CDR/RDR in column 1. PREDICTION_TIME 3 17 ASCII_Real 9 day Prediction time, in days, since the OD data cut-off of the navigation SPK used in this model. Note that a negative values indicates that the orbit is reconstructed. ALONG_TRACK_CORRECTION 4 26 ASCII_Real 11 km Correction applied to the orbit to have MLA data match known MLA topography basemap. The correction has three components; along-track, across-track, and radial. This value is the along-track component of the correction, in km. CROSS_TRACK_CORRECTION 5 37 ASCII_Real 10 km Correction applied to the orbit to have MLA data match known MLA topography basemap. The correction has three components; along-track, across-track, and radial. This value is the cross-track component of the correction, in km. RADIAL_CORRECTION 6 47 ASCII_Real 10 km Correction applied to the orbit to have MLA data match known MLA topography basemap. The correction has three components; along-track, across-track, and radial. This value is the radial component of the correction, in km. INITIAL_RMS 7 57 ASCII_Real 9 m Initial altimetric residual RMS in meters. The returns are compared to values derived from an existing MLA topography basemap at the predicted location prior to adjustments being made. FINAL_RMS 8 66 ASCII_Real 8 m Final, minimized altimetric residual RMS in meters. The location of the spacecraft is adjusted to minimize the residual between measured values and those derived from an existing MLA topography basemap. NUMBER_DATA_PTS 9 74 ASCII_Integer 6 The number of ground returns measured by the MLA instrument in this CDR/RDR that are used to minimize RMS. MIN_ALTITUDE_P2C 10 80 ASCII_Real 9 km The predicted minimum altitude of the spacecraft above topography as predicted by the navigation orbit prior to correction. This value was valuable to assuring the spacecraft's safety. MIN_ORBITAL_RADIUS_P2C 11 89 ASCII_Real 9 km The predicted minimum orbital radius of the spacecraft in kilometers prior to applying any correction. TIME_AT_MIN_RADIUS_PRED 12 98 ASCII_Real 13 s The predicted time at which minimum orbital radius would be encountered by the spacecraft in seconds since J2000. MIN_ALTITUDE_CORR 13 111 ASCII_Real 9 km The corrected minimum altitude of the spacecraft above topography as calculated using MLA data and the MLA digital elevation model. This value was valuable to assuring the spacecraft's safety. MIN_ORBITAL_RADIUS_CORR 14 120 ASCII_Real 9 km The corrected minimum orbital radius of the spacecraft in kilometers. TIME_AT_MIN_RADIUS_CORR 15 129 ASCII_Real 13 s The corrected time at which minimum orbital radius would be encountered by the spacecraft in seconds since J2000.