In-Situ Science Instruments in a Radioisotope Power System Environment

Abstract

Radioisotope Power Systems (RPS) have enabled or enhanced many historic and current space missions. Concepts for future missions that could be powered by RPS include insitu missions to the atmospheres, surfaces, and interiors of Europa, Titan, and other destinations. Such mission concepts are often tightly constrained on mass and volume, while still needing to support the instrument packages necessary to carry out ambitious science investigations, such as the search for signs of life. The physical proximity of RPS to payloads and to the in-situ environment has the potential to impact science instruments and science measurements. Radiation, thermal, vibration, electromagnetic interference (EMI), and magnetic fields impacts must all be considered carefully. This paper looks at existing and potential future RPS designs that could support insitu missions, and discusses possible interactions with in-situ instruments, including those under development to open up new avenues of scientific discovery. In-situ operations have additional complications compared to in-space operations, including unique environments, and packaging and form factor requirements that drive spacecraft designs. Radiation, EMI, and magnetic fields from RPS could be an order of magnitude higher than for orbital spacecraft, if the RPS must be packaged within the element instead of mounted externally. Waste heat from RPS could cause changes to the local environment around the spacecraft, particularly in an atmospheric or subsurface environment. Vibrations produced by potential future dynamic RPS could interfere with seismic measurements. In addition, in-situ investigations can require different instrument technologies and measurement approaches. Many of these instrument types have not yet flown and require additional development to make them flight capable in the small volumes available for payloads. These developments will have implications for the instruments and their interactions with the RPS environment. Furthermore, all this is complicated by the fact that in-situ mission concepts can vary wildly from one another. Balloon elements have very different requirements compared to melt probes and submarines. Mission designers must consider these characteristics along with RPS and instrument accommodations.