Reformatting Opportunity’s memory is the top thing on NASA’s to do list. The point is to clear away the flash memory. But what is flash memory? Flash memory stores information in an array of memory cells made from floating gate transistors. There all sorts of flash memory types from the once more traditional single-level cell (SLC) devices and then there is the multi level cell (MLC) devices which have multiple levels of electrical charge to apply to the floating gates. (Which may or may not be conductive, depends on the type…) Anyway, the risk if this does not get done is that a high radiation environment, the on-chip charge pump is the first part of the flash chip to fail. In such an environment they manage to keep working but in READ ONLY mode.
BUT by ‘cleaning’ the memory not only does NASA download to Earth the current data and clear away the existing data from Opportunity’s ‘brain’, but reformatting also helps to identify the bad cells and flag them in order to avoid them.
Resets, 12 in August alone, are the evidence needed to know that it is time. NASA also plans to change the current operating mode to one that doesn’t use flash memory and alter the manner in which it communicates data – using a slower rate but adding resilience.
So really, why reformat? For one – think of your own computer at home, which isn’t likely to have a similar amount of data added each day. Still – it needs to have system checks and to defragmented every so often and you still can’t stop that day where eventually the system just no longer boots up. Well, this one is significantly better made as there is no computer store within rover-roaming distance. If the many electronic updates and re[airs weren’t done, it would now be a large metal paperweight in Martian history books. The fact that it has survived this long is a truly amazing thing. Look at Spirit.
Spirit, poor thing, lasted only six years. Of course that is well over the 90 day life-span each of the rovers was given. The problem with Spirit was that it lost the ability to execute any tasks given that requested memory from the flight computer. The issue was in Spirit’s configuration of parameters in 2 OS (Operating System) modules which controlled the storage of files in system memory and flash memory. As a result there were many resets and re-initializations, reallocation of system memory, deletion of unnecessary files in the directory and so on. AND all this on something that was between 35 and 230 million miles away – impressive, no?!
So what can be expected? Well for one all the data will be gone but as NASA plans on retrieving it as part of the process, that’s no problem. Two – she will theoretically run better, be problem free with the need for the resets and re-initializations will be gone. Basically her life will be extended.
So here’s to you Opportunity;