Hover testing of a prototype small planetary spacecraft

We report on the design, building and free-flight hover testing of a prototype small planetary spacecraft. The Modular Common Bus (MCB) is being developed as a flexible, low cost spacecraft for both orbiting and landing on the Moon as well as a variety of other celestial targets. A prototype hover vehicle was built using the MCB design. It used the same structure, processor and avionics hardware and software development methodology as the MCB, but used a thrust equivalent pressurized cold-gas propulsion system, rather than a bipropellant system. This paper summarises the performance characteristics of the successful free-flights, including the measured attitude and position control and the propulsion and structural performance. The prototype's flight time of 7 s, being much greater than the vehicle control timescale, was adequate to determine stable 6 DoF attitude control. The cold-gas propulsion system allows flights to be repeated on a timescale of under one hour, many orders of magnitude less than they bipropellant equivalents, and thus the tests allow fast iterative development of the MCB design, as well as the collection of data that can enable the design to gain higher technological readiness in preparation for potential spaceflight missions. An analysis of the approach methodology of hover testing for low cost spacecraft is provided.