Active Recovery and Self Healing. This technique can be used to increase the MTBF to the length of time an item will be required to be used without maintenance. As an example, failure is expected for space vehicles that can be required to operate correctly for as much as 10 years in a hostile environment. Redundancy can be achieved by launching a large number of satellites, which is a practical solution for things like the Global Positioning System (GPS) because each vehicle occupies a slightly different orbit. This is not possible for geosynchronous orbit, where all functions must be accomplished by one vehicle that performs all functions must maintain stable position over one specific spot over the earth surface. Satellites intended to operate in geosynchronous orbit must incorporate active recovery that prevents total failure when one or more parts fail. Automatic Corrective Action incorporates all of the spare parts into the design to accommodate all of the failures that can be anticipated during a specific period of time. Manual Corrective Action Manual corrective action is when trained maintenance personnel perform a calibration or replacement action to restore operation. Corrective actions for redundant items includes manual reconfiguration when automatic fault bypass is not available, which depends upon maintenance coverage. Failed part replacement depends upon the Lowest Replaceable Unit (LRU). This could be a part inside an item, or it could be the whole item. This decision is made based on which is less expensive to replace. As an example, a new disk drive costs about $200 to purchase, the technical assistance to replace the disk drive is $500, and a refurbished computer costs about $600. If you replace your own disk drive and install your own operating system, then it is less expensive to purchase the disk drive. If you need technical help then it is less expensive to replace the whole computer. Operational Verification Operational Verification is any action that is performed to verify that the item or system is operational. This generally involves using the system in its normal mode of operation, which could involve actual operation or simulated operation. Reliability Maintenance is closely associated with reliability because maintenance is required to restore capability that has been lost due to failure. Electronic devices decay in a way that is mathematically equivalent to radioactive decay processes for unstable atoms. Electronic failure is governed by random processes, where Mean Time Between