Assembly, test and launch operations for a nuclear-enabled NASA mission: Considerations that are specific to use of a nuclear power system

For more than five decades, Radioisotope Power Systems (RPS) have played a critical role in the exploration of space, enabling missions of scientific discovery to destinations across the solar system by providing electrical power to explore remote, challenging and extreme environments. In particular, RPS enable deep space missions where increased heliocentric distances reduce the ability of solar power to adequately meet spacecraft and instrumentation power requirements. Some previous notable missions that were enabled by RPS include Nimbus III, the Apollo Surface Experiments, the Pioneers 10 and 11, the Viking Mars Landers, Galileo, Ulysses, Cassini, New Horizons and Curiosity. The current operating set of missions that are enabled by RPS are Voyagers 1 and 2, Cassini, New Horizons, and Curiosity. The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) is the current RPS used for Curiosity and upcoming Mars 2020 missions. An enhanced version of this generator outfitted with higher efficiency thermoelectrics is under development for potential use in the future. Other previously deployed power systems include the Multi-Hundred Watt Radioisotope Thermoelectric Generator (MHW-RTG) and the General Purpose Heat Source Radioisotope Thermoelectric Generator (GPHS-RTG). The common thread for all of these power systems is that they are fueled with Pu-238 in the oxide form. To ensure mission success and meet safety and security challenges, the use of this unique isotope involves additional planning activities and requires specific actions when the devices are delivered to the National Aeronautical and Space Administration (NASA) John F. Kennedy Space Center (KSC), and incorporated into the assembly, test and launch operations (ATLO) process.. It has been forecasted that the use of a nuclear reactor-based power system is on the horizon. This nuclear reactor-based power system could be used for either specifically powering spacecraft’s propulsion system or for surface power use once the mission arrived at its destination. Since a nuclear reactor-based system has never been handled or integrated into a spacecraft at KSC, an integration of this nuclear reactor-based power system would potentially introduce further challenges than those of RPS that must be accounted for in the ATLO process. This paper will explain ATLO considerations for recent MMRTG-enabled missions that have occurred and those planned for the near future (Mars 2020 NASA mission). In addition, this paper will discuss challenges for integrating a nuclear reactor-based power system onto a space mission. Specifically, the following topics will be addressed: • Approach for nuclear safety planning for nuclear material use and its transportation to space mission launch site • Plan for security posture for nuclear materials at launch site • Preparation for transportation of the nuclear power system from the fueling and testing location to the launch site • Preparation of documentation and procedures for nuclear material use at launch site • Plan for coordination between nuclear power system and space mission teams • Plan for appropriate staffing and scheduling of testing and operations • Plan and considerations for the integration operations of the nuclear powered spacecraft into the launch vehicle systems • Future Considerations for a Nuclear Reactor-Enabled Space Mission.