Actuator Sizing and Utility Assessment of Control Moment Gyroscopes for an Astronaut EVA Jetpack

A broad range of human space exploration missions could benefit from an astronaut mobility unit capable of providing six-degree-of-freedom control during extravehicular activities (EVAs). Currently, NASA is developing a Jetpack unit based on the Simplified Aid for EVA Rescue (SAFER) emergency self-rescue unit that provides translation and attitude control with fixed thrusters. The addition of small control moment gyroscopes (CMGs) to the Jetpack’s attitude control system could improve the stability of the EVA platform, conserve onboard fuel and extend the length of EVA missions. In particular, a Mobility-Augmenting Jetpack with Integrated CMGs (MAJIC) system might provide the most benefit to astronauts participating in EVA scenarios including surface sample collection, equipment deployment, satellite servicing, crewmember rescue, and contingency EVA missions at objects lacking built-in handholds or foot restraints. In order to properly assess the utility of the proposed MAJIC system, appropriately sized actuators have been identified with simulation. Monte Carlo analyses constrained to reflect realistic CMG size, mass, power and flywheel motor limitations have resulted in the identification of a design point for MAJIC system CMGs, and a performance and utility analysis indicates that the MAJIC system may outperform jetpacks without CMGs.