EnVision SPK files ============================================================================== This ``aareadme.txt'' file describes the contents of the kernels/spk directory of the EnVision SPICE Kernel Dataset. It was last modified on June 5, 2025 by Alfredo Escalante, ESAC/ESA. Contact Information ----------------------------------------------------------------------------- If you have any questions regarding this file contact the ESA SPICE Service (ESS) at ESAC: Alfredo Escalante Lopez (+34) 91-8131-429 spice@cosmos.esa.int References and required readings ----------------------------------------------------------------------------- 1. ``SPK Required Reading'', NAIF Document Brief Summary ----------------------------------------------------------------------------- This directory contains the SPICE SP-Kernel files for the EnVision mission, including mission analysis, nominal and operational spacecraft trajectory SPKs, generic planetary and satellite ephemerides SPKs, and EnVision structure and sensors' locations SPKs. File naming conventions ----------------------------------------------------------------------------- Naming Scheme for EnVision spacecraft SPKs: The naming scheme for the EnVision spacecraft SPKs is: envision_TYPE[_DESC][_ID][_YYMMDD_YYMMDD]_vNN.bsp where TYPE Data type, where a reference to the originator of the data, the type of data and the and the reference period is provided. The different types are: orbc S/C reconstructed and predicted cruise orbit from Flight Dynamics. orbm S/C reconstructed and predicted cruise orbit to which ATTM CKs are consistent to, from Flight Dynamics. crema Full mission test reference trajectory based on a crema document issue from Mission Analysis. crema_plan Full mission test reference trajectory based on a crema document issue from Mission Analysis trim for start date matching with orbc Flight Dynamics trajectory. mat_crema Full mission test reference trajectory based on a crema document issue from Mission Analysis (old reference); DESC description of the original reference file (optional); e.g. ET1_2031_NorthVOI_ML008 ID Mapping to the original file product IDs as defined per an ICD document ([2] and [3]) (optional); YYMMDD coverage start and stop times in TDB (optional); NN version number, starting from 01 (required; e.g. 01); Naming Scheme for Generic Planetary Ephemeris SPKs The naming scheme for generic planetary SPKs is: deNNN.bsp where NNN DE version (required; e.g. 421); Naming Scheme for NASA DSN ground stations SPKs The naming scheme for NASA DSN ground stations SPKs is: earthstns_fx_YYMMDD.bsp where YYMMDD product creation time (required); Naming Scheme for ESA ESTRACK ground stations SPKs The naming scheme for ESA ESTRACK ground stations SPKs is: estrack_vNN.bsp where NN version (required; e.g. 01); Other directory contents ----------------------------------------------------------------------------- aareadme.txt This file. Particulars ----------------------------------------------------------------------------- EnVision Example Trajectories ================================ VERSION: 2.0 CREATION_DATE: 2025/01/28 ORIGINATOR: ESA/ESOC CONTENT: Trajectory files in OEM (*.oem) format covering the science orbit phase: - ET1_2031_eO_NorthVOI_ML014: baseline scenario with Venus Orbit Insertion over the Northern hemisphere. * Note that this is the baseline scenario labelled as ET2_2023_N in the CReMA v2.1 - T1_2032_NorthVOI_ML014: backup scenario with Venus Orbit Insertion over the Northern hemisphere NOTES: - Trajectory data is consistent with JPL planetary ephemerides DE-432. - Venus gravity field expansion to 40x40 degree and order used for propagation of the science orbit. VERSION: 3.0 CREATION_DATE: 2020/06/10 ORIGINATOR: ESA/ESOC (P. Munoz) CONTENT: Trajectory files in OEM (*.oem) and Spice Kernel (*.bsd) formats covering the full mission duration consistent to the latest mission baseline: - ESC_T4_2032_NorthVOI: launch into direct escape at -5.0 deg declination and Venus Orbit Insertion over the Northern hemisphere. NOTES: - Trajectory data is consistent with JPL planetary ephemerides DE-432. - Aerobraking phase is not realistically modelled. Drag effect is emulated as several impulsive delta-Vs distributed throughout the aerobraking duration. - Science orbit time span (2035/06/15 - 2039/06/14) covering the nominal mission duration of 6 Venus cycles. - Venus gravity field expansion to 40x40 degree and order used for propagation of the science orbit. VERSION: 2.0 CREATION_DATE: 2019/07/26 ORIGINATOR: ESA/ESOC (P. Munoz) CONTENT: Trajectory files in OEM (*.oem) and Spice Kernel (*.bsd) formats covering the full mission duration for two different scenarios: - ESC_T2_2032_SouthVOI: launch into direct escape at -3.0 deg declination and Venus Orbit Insertion over the Southern hemisphere. - HEO_T2_2032_NorthVOI: launch into HEO (310x100,000 km) and Venus Orbit Insertion over the Northern hemisphere. NOTES: - Trajectory data is consistent with planetary ephemeris DE-432. - Aerobraking phase is not realistic neither in duration nor in dynamic modelling. - Science orbit time span (2034/11/26 - 2040/03/24) extended to account for the uncertainty in the date of aerobraking finalisation. - Venus gravity field expansion to 40x40 degree and order used for propagation of the science orbit. Kernel File Details ----------------------------------------------------------------------------- The most detailed description of the data in a binary SPK file is provided in metadata included inside the comment area of the file. This information can be viewed using the utility programs COMMNT and SPACIT included in the NAIF Toolkit. End of aareadme file.