AQT-D: CubeSat Demonstration of a Water Propulsion System Deployed from ISS

The AQua Thruster-Demonstrator (AQT-D) is a 3U CubeSat for demonstrating the water resistojet propulsion system developed by the University of Tokyo. The AQT-D was launched to rendezvous with the International Space Station (ISS) in the middle of 2019. This spacecraft will also be the world’s first ISS-deployed CubeSat equipped with a water propulsion system. AQT-D is comprised of a 1U propulsion system and 2U bus systems. The bus systems of the AQT-D were designed and developed based on the TRICOM-1R, also known as "Tasuki," was launched using a SS-520 nanosatellite launcher and was in operation during 2017-2018. The AQUA ResIstojet propUlsion System (AQUARIUS-1U) has one Delta-V-Thruster (F: 4 mN) for orbital maneuver and four Reaction-Control-Thruster (F: 1 mN) for reaction control. AQUARIUS-1U is a resistojet propulsion system comprised of a tank, a vaporization chamber and nozzles. It uses water as a propellant (i.e., propellant mass was less than 400 g. Ultimate green propellant: water (H2O) enables ISS-deployed CubeSat to install a propulsion system. It is expected that use of the CubeSat deployed by the ISS will expand drastically as the propulsion system lengthens the satellite lifetime, which is one of the bottlenecks for the low-earth-orbit CubeSat. This paper discusses the mission overview of the AQT-D and the ground test results of the propulsion system installed in it.