Hera MK files =========================================================================== This ``aareadme.txt'' file describes the contents of the kernels/mk directory of the Hera SPICE Kernel Dataset. It was last modified on April 26, 2024 by Alfredo Escalante Sitja, ESAC/ESA. Brief Summary ----------------------------------------------------------------------------- This directory contains the SPICE Meta-Kernel files for the Hera 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 appropriate to group kernels that correspond to a certain study group, phase or kernel state of the mission. File naming conventions ----------------------------------------------------------------------------- Naming Scheme for Hera spacecraft MKs: The naming scheme for the Hera spacecraft MKs is: hera[_DESC][_vXXX][_TAG][_NNN].tm where DESC a brief description of the scope of study of the scenario (optional); vXXX version number that corresponds to the version of the meta-kernel or the SPICE Kernel Dataset release number (optional; e.g. v121 for Release 1.2.1) TAG a time tag of the MK generation time (optional; e.g. 20160928); NNN a count of the MK version generated for a given TAG (mandatory if TAG is included; e.g 001) 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 former_versions Directory where versions no longer valid are stored for archive purposes.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. In general missions in operations will have an "operational" Meta-Kernel. This MK will contain the latest SPICE kernels available for the mission including those kernels generated by the operational pipeline in a periodical basis (namely SPK, CK and SCKL files). This MK should be used for Data Analysis or exceptionally Very Short Term Planning (VSTP). Since the periodicity of this 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/hera/kernels/mk/hera_ops.tm the following duplicate is generated: ftp/data/SPICE/hera/kernels/mk/hera_ops_v111_20220928_001.tm Please note that in order to conduct Long, Mid and Short Term planning (LTP/MTP/STP) users should use the planning meta-kernel. This meta-kernel does not contain the OEMS orbit files and SATS attitude files delivered by FDy nor the measured CKs. The release schema is analogue to the one for the operational meta-kernel. For what concerns dataset version kernels, they are generated when a new version of the kernel dataset is released. In parallel a new operational version is made available. New kernel datasets are typically released when new text kernels are added, updateed or modified, when there is a change in the directory structure, etc. Superseded version kernels are moved to the 'former_versions' directory. Kernel File Details ----------------------------------------------------------------------------- Name Comments --------------------------------------------------------------------- hera_crema_2_0_DESCR.tm Contains the latest available CReMA 2.0 kernels generated by the ESA SPICE Service. Where DESCR: - LPO: Launch Period Open. - LPC: Launch Period Close. - ECP: Early Characterization Phase. - PDP: Payload Deployment Phase. hera_crema_2_0_DESCR_vXXX_YYYYMMDD_NNN.tm Is a duplicate of the CReMA 2.0 MK that derived from release vXXX. If multiple study MK files are generated on the same date the version NNN is increased starting from 001. Read the ``Particulars'' section for more information. hera_study_DESCR.tm Contains the latest available study kernels generated by the ESA SPICE Service. Where DESCR: - PO: Proximity Operations based on the trajectories reported on RD27. - EA: Earth-Didymos transfer. - EMA: Earth-Mars-Didymos transfer. hera_study_DESCR_vXXX_YYYYMMDD_NNN.tm Is a duplicate of the study MK that derived from release vXXX. If multiple study MK files are generated on the same date the version NNN is increased starting from 001. Read the ``Particulars'' section for more information. Contact Information ----------------------------------------------------------------------------- If you have any questions regarding this directory or its contents, please contact SPICE support at ESAC: Alfredo Escalante Lopez (+34) 91-8131-429 spice@cosmos.esa.int or NAIF at JPL: Boris Semenov (818) 354-8136 Boris.Semenov@jpl.nasa.gov References and required readings ----------------------------------------------------------------------------- 1. ``Kernel Required Reading'', NAIF Document End of aareadme file.