AQT-D


AQT-D is a nanosatellite project of the University of Tokyo Space Propulsion Laboratory with the purpose of testing water-fueled propulsion. The satellite is a CubeSat of 3U size; 1U is occupied by the propulsion system, while the remaining 2U is for the spacecraft bus. AQT-D will be carried to space inside the pressurized section of Kounotori 8, a Japanese resupply vehicle for the International Space Station. Kounotori 8 was launched on 24 September 2019. After arriving at the ISS, AQT-D was deployed to space on 20 November 2019 using the JEMRMS robotic arm at the space station's Kibo laboratory module.
The AQT-D project is led by Jun Asakawa of the University of Tokyo.

Spacecraft

AQT-D's spacecraft bus is based on Tasuki, a previous satellite developed by the University of Tokyo and launched in 2017. The satellite is equipped with antennas for store and forward communication.

Propulsion

Water thrustersUnit/performance
PropellantWater
Thrust1 - 4 mN
Specific impulse>70 s
Water mass< 0.4 kg

AQT-D's propulsion system, called AQUARIUS-1U, consists of five water thrusters. A single ΔV thruster produces 4.0 mN, and four reaction control thrusters 1.0 mN, for attitude control. The spacecraft will carry less than 0.4 kg of water. The ΔV thruster produces a specific impulse of 70 s, and a maximum 4.0 mN of thrust, which is dependent on available power. AQUARIUS-1U's design was based on the planned deep space probe EQUULEUS's propulsion system. According to the University of Tokyo, AQT-D will be the first ISS-deployed satellite to have water-based propulsion. While satellites deployed from the ISS typically have a short lifetime owing to the station's low altitude, satellites equipped with a propulsion system like AQT-D may potentially remain in orbit for an extended period of time.