JUICE MK files =========================================================================== This ``aareadme.txt'' file describes the contents of the kernels/spk directory of the JUICE SPICE data server. It was last modified on October 21, 2022 by Marc Costa Sitja, 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@sciops.esa.int or the JUICE Science Operations Center at ESAC: Marc Costa Sitja (+34) 646-746-711 Marc.Costa@ext.esa.int References and required readings -------------------------------------------------------- 1. ``Kernel Required Reading'', NAIF Document Brief Summary -------------------------------------------------------- This directory contains the SPICE Meta-Kernel files for the JUICE mission. Meta-kernels (also known as ``FURNSH kernel'') are used to name a collection of kernels that are to be loaded into a user's application at run-time. Meta-kernels are appropiate to group kernels that correspond to a certain study group, phase or kernel state of the mission. File naming conventions -------------------------------------------------------- Naming Scheme for JUICE spacecraft MKs: The naming scheme for the JUICE spacecraft MKs is: juice[_ID][_DESC][_TAG][vNNN].tm where ID mapping to the original trajectory file product IDs as defined per the original Mission Analysis filename (optional) e.g.: DESC a brief description of the scope of study of the trajectory (optional); TAG a time tag of the MK generation time (optional; e.g. 20160928); vNNN version number that corresponds to the current SPICE kernel dataset release (optional; e.g. v100); Other directory contents -------------------------------------------------------- aareadme.txt This file. former_versions Directory where versions no longer valid are stored for archive purposes. Particulars -------------------------------------------------------- Meta-Kernel file management is a critical element of any SPICE dataset. For ESA Planetary Missions the Meta-Kernels of the operational SPICE repositories are also used to control the version of the SPICE dataset. JUICE has a number of meta-kernels that contain information of the so-called crema document; these are trajectories provided by Mission Analysis for the development phase. These meta-kernels are used for studies and development. In general missions in operations will have an ``operational'' meta-kernel (OPS) and a ``planning'' meta-kernel (PLAN). For JUICE the OPS MK includes as-flown information and short-term attitude and trajectory files from Flight Dynamics whereas the PLAN MK includes predicted and test trajectory and orientation from the Science Operations Center and Flight Dynamics. More in detail: The OPS meta-kernel will contain: - Trajectory: Predicted and reconstructed from Flight Dynamics (FDy); the data is in the same file, typically includes reconstruction and a predicted segment) - Attitude: As-flown orientation data from the Housekeeping (HK_TM) Telemetry and predicted/commanded attitude from FDy. The FDy prediction will be overwritten by the HK_TM - Structures/Payload: As-flown orientation without a default profile (there might be data gaps) The PLAN meta-kernel will contain: - Trajectory: Predicted and reconstructed from FDy plus the crema trajectories from Mission Analysis. - Attitude: Predicted/commanded attitude from FDy and test attitude for the Cruise phase and Tour generated by the SOC - Structures/Payload: Default profile (usage is not recommended). Since the periodicity of these updates ranges from hours to weeks, the MK in the Meta-Kernel directory does not have a version number and is regularly overwritten. Nevertheless, in order to keep traceability and backwards compatibility with former MKs, a duplicate of every generated operational MK is stored. This duplicated MK filename is appended with a time tag and a version; if the original MK looks like: ftp/data/SPICE/JUICE/kernels/mk/juice_ops.tm the following duplicate is generated: ftp/data/SPICE/JUICE/kernels/mk/juice_ops_v230_20221128_001.tm Kernel File Details -------------------------------------------------------- Name Comments --------------------------------------------------------------------- juice_crema_ID.tm Contains the latest version of the information defined by the crema document issue and trajectory as described by ID. juice_crema_ID_vXXX[_YYYYMMDD_NNN].tm Is a duplicate of the crema MK that derived from ID. If multiple operational MK files are generated on the same date the version NNN is increased starting from 001. The YYYYMMDD_NNN tag is optional. juice_ops.tm Contains the latest available operational kernels generated by the SPICE operational pipeline. juice_ops_vXXX_YYYYMMDD_NNN.tm Is a duplicate of the operational MK that derived from release vXXX. If multiple operational MK files are generated on the same date the version NNN is increased starting from 001. Read the ``Particulars'' section for more information. juice_plan.tm Contains the long, mid and short term operational kernels generated by the SPICE operational pipeline. juice_plan_vXXX_YYYYMMDD_NNN.tm Is a duplicate of the planning MK that derived from release vXXX. If multiple operational MK files are generated on the same date the version NNN is increased starting from 001. Read the ``Particulars'' section for more information. End of aareadme file.