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Galactic cosmic rays (GCRs) are an intrinsic part of the heliospheric radiation environment and an inevitable challenge to long-term space exploration. Here we show solar-cycle-induced GCR modulation at Mars in the period 2005–2020, along with GCR radial gradients, by comparing Mars Express and Rosetta engineering parameters to sunspot number time series. The engineering parameters used are the error detection and correction (EDAC) counters, cumulative counters that are triggered by charged energetic particles that cause memory errors in onboard computers. EDAC data provide a new way of gaining insight into the field of particle transport in the heliosphere; these data also allow us to complement dedicated radiation instrumentation as EDAC software is present on all spacecraft. This dataset was used to capture variations in GCRs in both space and time, yielding the same qualitative information as ground-based neutron monitors. Our analysis of the Mars Express EDAC parameter reveals a strong solar cycle GCR modulation, with a time lag of ∼5.5 months. By combining Mars Express with Rosetta data, we calculate a 4.7 ± 0.8% increase in EDAC count rates per astronomical unit, which we attribute to a radial gradient in GCR fluxes in accordance with established literature. The potential of engineering data for scientific purposes remains mostly unexplored. The results obtained from this work demonstrate, for the first time for heliophysics purposes, the usefulness of the EDAC engineering parameter, the usefulness of data mining, and the utility of keeping missions operational for many years, all of which provide complimentary data to nominal science instruments.

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Mars Express has been in orbit around Mars since 2003, relying on the Solid State MassMemory (SSMM) to hold a "mission time-line" (MTL) of 3000 commands, refreshed daily, to execute the mission. The MTL schedules transmitter switching, spacecraft pointing and instrument operations. The original operations concept called for the MTL to be kept as fully loaded as possible, as early as possible. In 2011, Mars Express suffered from five SSMM-related anomalies, three of which put the spacecraft into safe mode. The safe-modes were caused by an inability of the MTL to refill its cache of commands, due to the SSMM anomalies. As each safe mode expends roughly 6 months' of fuel, the decision was taken to halt science and non-Earth pointing operations. Another MTL independent from the SSMM exists in processor RAM. This "short MTL" contains space for only 117 commands. A new concept, the File-base Activities with Short Timeline (FAST), was devised to restart science operations as soon as possible. The core of the concept relies on storing commands in the SSMM in discrete files that contain an entire "activity". Critically, "an activity" always starts and ends with the spacecraft in a safe configuration. These command files, always fewer than 100 commands, are loaded into the short MTL in a just-in-time scheme, via "trigger" commands in the MTL, and activating the activity commands only if the file loads completely. This all-or-nothing approach provides robustness to possible further SSMM anomalies by preventing them from causing a safe mode. This paper will present the new operations concept, the additional safety mechanisms, the implementation approach onboard and on-ground, the challenges for team and knowledge management, as well as the achieved performance of the so-rehabilitated mission.