JPL Pub 04-10 Enabling Exploration with Small Radioisotope Power Systems Requested by George R. Schmidt NASA Office of Space Science Written by Robert D. Abelson (Editor) JPL/Caltech Tibor S. Balint JPL/Caltech Kathryn E. Marshall JPL/Caltech Heros Noravian Analytix/DOE James E. Randolph JPL/Caltech Celeste M. Satter JPL/Caltech George R. Schmidt NASA HQ James H. Shirley JPL/Caltech September 2004 GSFC Prepared by the Jet Propulsion Laboratory, California Institute of Technology and the U.S. Department of Energy through an agreement with the National Aeronautics and Space Administration. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government, the U.S. Department of Energy, or the Jet Propulsion Laboratory, California Institute of Technology. SMALL RPS CONCEPTS TABLE OF CONTENTS Table of Contents 1. Summary ............................................................................................................................... 1-1 1.1 Background................................................................................................................... 1-1 1.2 Purpose ......................................................................................................................... 1-3 1.3 Results .......................................................................................................................... 1-4 1.4 Conclusions .................................................................................................................. 1-8 2. Mission Concepts and Applications ..................................................................................... 2-1 2.1 Purpose and Objectives ................................................................................................ 2-1 2.2 Introduction and Description of the Mission Categories.............................................. 2-1 2.3 Lander Missions ........................................................................................................... 2-2 2.3.1 Europa Lander Mission....................................................................................... 2-2 2.3.2 Additional RPS-Enabled Lander Missions ....................................................... 2-15 2.3.3 Summary and Conclusions ............................................................................... 2-16 2.4 Rover Missions .......................................................................................................... 2-17 2.4.1 Mars Rover Mission.......................................................................................... 2-17 2.4.2 Lunar Rover Mission ........................................................................................ 2-29 2.4.3 Conclusions of Rover Mission Studies............................................................. 2-43 2.5 Subsatellite Missions.................................................................................................. 2-46 2.5.1 Galilean Satellite Orbiter Mission .................................................................... 2-46 2.5.2 Additional RPS-Enabled Subsatellite Missions ................................................ 2-58 2.5.3 Summary and Conclusions .............................................................................. 2-58 2.6 Deployable Mini-Payload Applications ..................................................................... 2-59 2.6.1 Seismic Monitoring Stations............................................................................. 2-59 2.6.2 Passive Fields and Particles Monitoring Station............................................... 2-64 2.6.3 Summary and Conclusions ............................................................................... 2-66 2.7 Mission Studies Summary.......................................................................................... 2-68 3. Power Conversion Technologies for Small-RPS Systems ................................................... 3-1 3.1 Thermoelectrics ............................................................................................................ 3-1 3.2 Stirling .......................................................................................................................... 3-2 4. Small-RPS Concepts ............................................................................................................. 4-1 4.1 Hi-Z Milliwatt RPS Concept........................................................................................ 4-1 4.2 JPL/Swales Milliwatt RPS Concept ............................................................................. 4-1 4.3 ARC Milliwatt RPS Concept........................................................................................ 4-2 4.4 BIAPOS Milliwatt RPS Concept.................................................................................. 4-3 4.5 DOE/OSC RPS Concepts............................................................................................. 4-3 4.5.1 GPHS-Based RPS Concepts ............................................................................... 4-4 4.5.2 RHU-Based RPS Concepts (40 mWe) ................................................................ 4-7 4.5.3 RHU-Based RPS Concept (160 mWe) ............................................................. 4-10 4.6 Small-RPS Concepts Summary.................................................................................. 4-11 5. Acknowledgements ............................................................................................................... 5-1 6. References ............................................................................................................................. 6-1 7. Acronyms and Abbreviations ............................................................................................... 7-1 i The information contained within this document is predecisional and for discussion purposes only. TABLE OF CONTENTS SMALL RPS CONCEPTS ii The information contained within this document is predecisional and for discussion purposes only. SMALL RPS CONCEPTS LIST OF FIGURES List of Figures Figure 1-1. Classes of Small-RPS Dictated by Available Pu-238 Heat Sources .................. 1-4 Figure 2.3.1-1. Europa’s Predicted Internal Structure and Composition ................................... 2-2 Figure 2.3.1-2. Configuration of the Europa Lander Mission (ELM) Surface Lander [7] ......... 2-3 Figure 2.3.1-3. Artist’s Concept of the ELM Spacecraft Riding the Aft Section of the JIMO Mothership (Preliminary Version) During the Cruise Phase ........ 2-3 Figure 2.3.1-4. Orbital Maneuvers Performed by the ELM Spacecraft During the Entry and Landing Phases ............................................................... 2-4 Figure 2.3.1-5. Illustrations of the separation, orbital-insertion, airbag deployment and landing phases of the Europa Lander Mission (ELM) spacecraft [7]. ........ 2-4 Figure 2.3.1-6. Incident Solar Flux at Surface of Europa at 45° Latitude Over 30 Earth Days ...................................................... 2-5 Figure 2.3.1-7. (a) Small-RPS (with Top Removed) and (b) ELM Spacecraft with Small-RPS Installed (Radiator panels and internal systems removed for clarity.) .............. 2-7 Figure 2.3.1-8. Communications Event Between ELM (at 45° latitude) and JIMO .................. 2-9 Figure 2.3.1-9. Elevation Line of Site (LOS) Angle between ELM and JIMO as a Function of Latitude and Time ....................................................... 2-10 Figure 2.3.1-10.ELM Power Requirements (Peak and Average) for Each Operating Mode ... 2-12 Figure 2.3.1-11.Natural Radiation Dose (4-Pi) Received by the JIMO Spacecraft Versus Shielding Thickness [15] ................................................... 2-14 Figure 2.3.1-12.Lifetime (13-year) Radiation Dose Generated by a GPHS Module Versus Distance [16] ............................................................... 2-14 Figure 2.4.1-1. Mars: Future Destination for Manned Space Exploration ............................... 2-17 Figure 2.4.1-2. MER-type Airbag without the Aeroshell ......................................................... 2-18 Figure 2.4.1-3. Viking-type Aeroshell, Lander, and Rover ...................................................... 2-18 Figure 2.4.1-4. Mars Rover Configuration (top removed to show internal systems) ............... 2-19 Figure 2.4.1-5. Operating Performance of a Mars Rover as a Function of Landing Location . 2-20 Figure 2.4.1-6. Conceptual Small-RPS for the Mars Rover Using a Single GPHS Module ... 2-21 Figure 2.4.1-7. Mars Rover Instrumentation Configuration and Layout ................................. 2-22 Figure 2.4.1-8. Thermal Design Concept for an RPS-enabled Mars Rover ............................. 2-23 Figure 2.4.1-9. Sojourner and the Rock Named Yogi .............................................................. 2-24 Figure 2.4.1-10.Design Concept View of the Mars Rover Wheels and the RPSs ................... 2-24 Figure 2.4.1-11.Radiation environment for two RPS mission concept configurations of the Mars Rover: (a) end-to-end configuration and (b) side-by-side configuration; dotted line represents area in radiation plots. ........................... 2-27 Figure 2.4.2-1. The Moon—Possible Source of Water Ice for Support of a Permanent Human Presence. .................................................................... 2-29 Figure 2.4.2-2. Lunar Rover Descent