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A comment today from Mars Express Spacecraft Operations Manager Michel Denis on this week's report: "MARSIS completes measurement campaign over Martian North Pole." The report gives good news!
"The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express has recently completed a subsurface sounding campaign over the planet's North Pole. The campaign was interrupted by the suspension of science observations several times between August and October due to safe modes and to anomalies in the operation of the spacecraft's Solid-State Mass Memory (SSMM) system. As MARSIS best observes in the dark, which for the North Pole only occurs every few years, it was among the first instruments to resume observations once a partial work-around for the problems had been implemented."
In his comment below, the 'FAST Method' that Michel refers to is the operations team's newly developed way of uploading commands to Mars Express, which avoids using the problematic Solid State Mass Memory (SSMM) for critical commanding.
The 'File-based Activities on Short Timeline' method essentially means that commands are grouped in very short self-contained files that can be loaded safely, in advance of execution, from the SSMM into an alternative memory unit (that is reliable but not as capacious as the SSMM).
Michel writes:
The FAST method - loading short command files upon need into the short onboard mission timeline - was put into use at the end of October 2011 with the (excellent) result that we could save what was remaining of the North Pole observation campaign by the MARSIS radar.
The net loss in data collection was mitigated by using the existing MARSIS command sequences as soon as possible. Meanwhile, as for the other instruments, new MARSIS on-board control procedures (OBCPs) are under development and will allow operation with fewer commands, therefore enabling the operation of several science instruments in parallel.
My main point? We did our job: contrary to widespread received wisdom, the spacecraft operators' role is not to simply watch over (supposedly) boring routine operations during the many long years of a mission - nor simply saving a spacecraft that experiences problems. In fact, we are relied upon to deliver safely as much of the expected (precious) scientific data as possible within the resources available - despite adversity. And that's what we're doing!
To allow the mission to restart operations of all instruments, we needed to write 'macro' on-board control procedures (OBCPs) to replace long sequences of telecommands with single 'start macro' telecommands that would fit into the restrictive memory space provided by the short mission time-line (Basically, all commands now have to be a lot shorter to be stored on board now that the solid state mass memory no longer functions properly - Ed.).
