SPICE Status and Updates for ESA Missions

Introduction:  SPICE is an information system the purpose of which is to provide scientists the observation geometry needed to plan scientific observations and to analyze the data returned from those observations. SPICE is comprised of a suite of data files, usually called kernels, and software -mostly subroutines [1]. The user incorporates a few of the subroutines into his/her own program that is built to read SPICE data and compute needed geometry parameters for whatever task is at hand. Some examples of geometry parameters typically computed are range or altitude, latitude and longitude, illuminations angles (phase, incidence and emission), instrument pointing and field-of-view calculations, reference frame transformations, and coordinate system conversions. SPICE is also very adept at time conversions. By combining just a few of these SPICE functions, users can compute complex quantities with only a few lines of code.

The ESA SPICE Service:  The ESA SPICE Service (ESS) leads the SPICE operations for ESA missions. The group generates the SPICE Kernel Datasets (SKDs) for missions in development (ExoMars Rover, RAMSES, Comet-Interceptor, EnVision, M-MATISSE), missions in operations (Mars Express, ExoMars 2016, BepiColombo, Solar Orbiter, INTEGRAL, JUICE and Hera) and legacy missions (Venus Express, Rosetta and SMART-1). Moreover, ESS provides SPICE support Kernels for Gaia, James Webb Space Telescope and Euclid. The generation of SKDs includes the development and operation of software to convert ESA orbit, attitude, payload telemetry and spacecraft clock correlation data into the corresponding SPICE format. ESS also provides consultancy and support to the Science Ground Segments of the planetary missions, the Instrument Teams and the science community. The access point for the ESS activities, data and latest news can be found at the following site https://www.cosmos.esa.int/web/spice. ESS works in partnership with NAIF (Navigation and Ancillary Information Facility, URL: https://naif.jpl.nasa.gov/naif/).

Status of the Kernel Datasets: The current status and latest developments of the SKDs for the before mentioned missions will be described in this contribution. In general, the ESS is reviewing the legacy and operational datasets and developing the ones for future missions. It is worth mentioning the cruise operations of JUICE now on its way to Jupiter system and the successful launch of Hera in October 2024 followed by a Deimos and Mars fly-by in March 2025.

SPICE Kernels Archived in the PSA. ESS is also responsible for the generation of PDS3 and PDS4 formatted SPICE Archives that are published by the PSA (Planetary Science Archive, URL: https://psa.esa.int/psa). ESS in close collaboration with NAIF, peer-reviews the operational kernels for the PSA [2] in order to publish being compliant with the Planetary Data System (PDS) standards and uses them in the processes that require geometry computations. The latest PDS4 SPICE Bundles are produced using the NAIF PDS4 Bundler tool [3] .

Figure 1: M-MATISSE studies geometry analysis reports for different scenario candidates.

 

From Concept to Legacy: SPICE has played a vital role in all ESA planetary missions, serving as a foundational tool for both planning future observations and analyzing scientific data. Even before the operational phase begins, SPICE is extensively used during Long Term Planning (LTP) to assess mission feasibility, evaluating factors such as target coverage, observation conditions, ground station visibility, illumination, power constraints, and other mission-critical events. For the most recent missions, its application has extended even earlier, into the initial stages of mission development and concept design. By modeling preliminary spacecraft configurations, potential design variations, and a range of candidate trajectories and attitude profiles within the SPICE framework, teams can extract valuable performance metrics. These insights not only help refine the mission architecture and evaluate high-level science objectives but can also directly influence spacecraft systems design, for instance, by optimizing payload placement and orientation.

Extended Services: ESS offers other services beyond the generation and maintenance of SPICE Kernel Datasets, such as instances and configuration for WebGeocalc and Cosmographia for the ESA missions, and additional software packages for geometric data exploitation.

SPICE-Enhanced Cosmographia. NAIF offers for public use a SPICE-enhanced version of the open source visualization tool named Cosmographia. This is an interactive tool devoted to 3D visualizations of celestial bodies ephemerides and shape models, spacecraft trajectories and orientations, movable parts position, and instrument field-of-views and footprints. ESS provides the framework and configuration required to load the ESA missions in Cosmographia, this contribution will demonstrate its usage for the ESA Solar System missions and how it supports critical events like the Hera Mars fly-by.

Figure 2: Hera spacecraft observations of Deimos and Mars on 12^th March 2025 during its fly-by displaying the pointing and field-of-views of Hera payload.

 

WebGeocalc. The WebGeocalc tool (WGC) provides a web-based graphical user interface to many of the observation geometry computations available from the SPICE APIs. A WGC user can perform SPICE computations without the need to write a program; just a web browser is required. WGC is provided to the ESS by NAIF. This contribution will outline the WGC instances for ESA missions.

 

References: [1] Acton C. (1996) Planet. And Space Sci., 44, 65-70. [2] Bessel, S. et al., (2017) Planet. And Space Sci. [3] Sitja, M. C. (2022) Journal of Open Source Software