VIPER Family Day Ethan Massey, in the control booth, sends commands that control the movement of the Moon Gravity Representative Unit (MGRU3) at the Roverscape during Family Day for team members of the Volatiles Investigating Polar Exploration Rover (VIPER). MGRU3 is a weight equivalent mobility and navigation test platform for VIPER. It is used to test, develop and validate the different mobility and navigation techniques and capabilities of the VIPER rover, to safely and efficiently map water at the Moon’s South Pole.