Data Structure, Temperature Log, and Backup Strategy

One Mossbauer spectrum consists of 512 velocity channels (3 bytes per channel). One temperature interval consists of five Mossbauer spectra (one for each detector). There are 13 temperature intervals with selectable width. Thus, MIMOS II can accumulate simultaneously up to 65 Mossbauer spectra during one experiment session on Mars. All Mossbauer, energy, engineering, and temperature data taken during this session are stored in a volatile SRAM (Static Random Access 

Memory) (128 KB) on the MIMOSII electronics board. Firmware parameters and the instrument logbook are stored in the nonvolatile memory ferroelectric RAM (FRAM) on the electronics board. There are three individual FRAMs on the MIMOS II electronics board with three identical copies of these parameters to ensure parameter integrity. The copies are compared with each other from time to time to verify that they are identical. If one copy deviates from the other two, it is replaced by a copy of the other two identical parameter sets. All parameters can be adjusted during mission operations. 

To minimize the risk of data loss because of power failure or other reasons, the Mossbauer data are copied to a nonvolatile EEPROM (Electrically Erasable Programmable Read-Only Memory) every 9 minutes (software selectable). As the size of the EEPROM is smaller than the SRAM, the EEPROM can accumulate only up to ten Mossbauer spectra as a subset of the data from the SRAM. These spectra are obtained from the SRAM according to a pre-defined summation strategy. 

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