Specific Energy is at the system level. The system is defined to include the flywheel modules, power electronics, sensors and controllers. Efficiency is measured at the system level as the. Flywheels can charge and discharge quickly and can be used as outposts for rover or EVA suit recharging. Flywheels can accommodate very high peak loads, reducing constraints and planning requirements for operations. Flywheels can operate over. A single flywheel system will replace three strings of Ni-H batteries on the IEA This configuration allows three options after the flight demonstration phase Flywheels only Flywheels paralleled.