In-flight propulsion system characterization for both Mars Exploration Rover Spacecraft

Two Mars Exploration Rover spacecraft were dispensed to red planet in 2003, culminating in a phenomenally successful prime science mission. Twin cruise stage propulsion systems were developed in record time, largely through heritage with Mars Pathfinder. As expected, consumable usage was minimal during the short seven-month cruise for both spacecraft. Propellant usage models based on pressure and temperature agreed with throughput models with in a few percent. Trajectory correction maneuver performance was nominal, allowing the cancellation of near-Mars maneuvers. Spin thruster delivered impulse was 10-12% high vs. ground based models for the intial spin-down maneuvers, while turn performance was XX-XX% high/low vs. expectations. No clear indications for pressure transducer drift were noted during the brief MER missions.