Mars Express is Europe’s first mission to Mars, and has been extremely successful. Since reaching Mars orbit in late 2003, the spacecraft has operated reliably and without significant anomalies. This consistency of operation allowed all its primary goals to be met (Mars surface, subsurface, and atmosphere), and more besides (Phobos observations, relay of NASA Lander data, to name but a few). The eight-year mission, with sometimes serious anomalies, was halted in August 2011 when repeated errors in the solid-state mass memory (SSMM) resulted in the spacecraft transitioning to a “safe mode” and the suspension of nominal operations. The anomalies persisted and led to a switchover to the redundant mass memory controller unit. Science operations were restarted, but within a month the spacecraft was in safe mode again. A third safe mode a few weeks later forced the halting of science operations while the problem was diagnosed. Each safe mode consumed up to six months’ worth of fuel and such frequent occurrences were unsustainable. As a deep-space mission with long periods out of contact with Earth, Mars Express relies on an SSMM to store telemetry, science, and command data [1]. As these command data are critical to the continuation of operations, any interruption in the flow of commands from the SSMM would result in a safe mode, and a requirement to point the high-gain antenna at Earth and ensure a stable
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