Rechargeable RCS Tank Operations Using Cryocoolers

Abstract

A cryogenic Reaction Control System (RCS) recharge technology using the waste heat and cooling capacity of a cryocooler to manage tank temperature and pressure has been developed. Traditional RCS tanks use ambient temperature and high-pressure storable propellants and are not rechargeable. For long duration missions, storable propellant tanks become prohibitively large and heavy, potentially exceeding launch vehicle mass and volume constraints. Another key factor in long duration space mission is implementing in-situ resource utilization (ISRU), the practice of using raw materials found on a planetary body to generate liquid cryogenic propellants. ISRU reduces initial vehicle and propellant mass as the vehicle only needs to carry enough propellant for one leg of the mission. To fully minimize initial vehicle and propellant mass RCS tanks must be refillable using cryogenic propellant from the main propellant tanks. A comprehensive thermal fluid model investigating the recharge system was developed to evaluate thermal performance. System performance over many configurations and initial inputs were run. Preliminary results indicate the system gasifies and transfers propellant at a minimum of 0.5 g/s. When compared to a conventional electric heater vaporization system, the RCS system offers mass savings along with a potential avenue to use waste heat from several systems to vaporize RCS propellant. System level integration of the cryocooler recharge technology offers a unique solution to cryogenically propelled, rechargeable RCS tanks.