A European mission to Mercury was first proposed in May 1993 and it was accepted as a one of ESA’s three cornerstone missions. In October 2000 ESA approved a package of missions for years 2008–2013 and the mission to Mercury was included.
The mission was named BepiColombo in honour of Italian space pioneer Giuseppe “Bepi” Colombo. BepiColombo will reach Mercury in late 2024, after a 6,7-year journey towards the inner Solar System, in order to make the most extensive and detailed study of the planet ever performed.
Active operating time at the Mercury’s orbit will be at least one earth year. BepiColombo will study and understand the composition, geophysics, atmosphere, magnetosphere, and history of Mercury, the least explored planet in the inner Solar System. It will provide the best understanding of Mercury to date. The mission is especially challenging because Mercury’s orbit is so close to our Sun, and therefore hard to observe from a distance, because of the the Sun’s brightness.
BepiColombo SIXS/MIXS project
SSF develops SIXS/MIXS onboard software, which runs in the combined Data Processing Unit (DPU) of the SIXS/MIXS instruments. In the early years of the project SSF had also System Engineering responsibility for the DPU.
The DPU is used to control instrument power and operating states, to monitor instrument operations and to handle telecommand and telemetry communications. Another responsibility of the SIXS/MIXS DPU is to convert scientific data from a very high number of individual detections to more manageable summary information, such as periodic summary counters, spectra, and histograms.
SSF responsibilities in the project have three phases: System Engineering, Software Development, and Maintenance.
SSF discussed with different stakeholders, gathered all the inputs and formalised overall System Requirements for the SIXS/MIXS project including scientific data processing algorithms, sensor and HW controlling, telemetry communications and failure mode surveillance.
According to formalized System Requirements, SSF designed basic system architecture, detailed functional requirements and work division between different system modules.
On-board software development
The active phase of the on-board software (OBSW) development lasted eight years. During that time SSF developed full functional OBSW and integrated it into the engineering model of the actual DPU hardware.
OBSW design process followed ESA’s strict standards and guidelines including coding standards and documentation. A worst case schedulability and full failure detection, isolation, and recovery were proven during the design.
To verify the full functional compliance with the requirements, OBSW functionalities were tested with 100 % coverage. To allow this, SSF built a test environment running developed SW binary in target hardware. Full input/output signaling was allowed by simulating surrounding measurement sensors, satellite interface and ground control station. Fully automated test procedures stored all test actions and results into the database.
The final delivery of the OBSW development was finished in spring 2014 and the SSF’s project moved to the maintenance phase. ESA continues the project together with instrument owners by integrating all the instruments into the Spacecraft. Spacecraft will be ready for the launch in 2024. After a 6–7 years journey, instruments will be actively operating at the Mercury’s orbit until 2025.
SSF supports system integration work and ground control operations during the mission. Upgrades for the OBSW are provided whenever further requirements or change requests are initiated. OBSW design allows SW patching from the mission ground control radio station using telecommanding interface – even if the devices are already in Mercury’s orbit and under the extreme heat of the Sun.