European Space Nuclear Power Programme: UK Perspective

Transcription

1 European Space Nuclear Power Programme: UK Perspective R. M. Ambrosi, H. Williams, N. P. Bannister, P. Samara-Ratna, J. C. Bridges, D. Vernon, C. Bicknell, T. Crawford, J. Sykes University of Leicester, Space Research Centre, Leicester, UK T. Jorden, M. Stuttard, R. Slade, M-C. Perkinson, J. Reed, T. Deacon Astrium Ltd, Stevenage, UK T. Rice, M. Sarsfield, T. Tinsley National Nuclear Laboratory, Warrington, UK C. Chaloner, W. Johnson SEA, Bristol, UK M. Reece Queen Mary University of London, UK K. Simpson European Thermodynamics Ltd, Kibworth, UK

2 Introduction Nuclear power systems in space in the form of radioisotope thermoelectric generators (RTGs), radioisotope heater units and fission based reactors have been used in space for ~half a century. Conversion of heat to electricity (Stirling cycle, thermoelectric converters, etc...). Mass efficiency ranges from ~3 Welectric/kg to ~7 Welectric/kg for radioisotope power systems. Reactors power outputs were in the ~1-5 kw electric range. US and Russia have been leaders in utilising this type of technology. Radioisotope generators and heaters have used Pu-238 as fuel source, which is in short supply. Europe is focused on Am-241. National Nuclear Laboratory in the UK is leading the efforts in the European studies focused on Am-241 fuel production for space applications.

3 Radioisotope Thermoelectric Generator

4 Enabling Technology Nuclear power is an important low carbon technology for the future energy security of the UK and Europe. In the context of space science and exploration radioisotope power sources (RPS) and space reactor technologies are enabling technologies for more challenging future space science and exploration programmes. Their use results in more capable spacecraft, extended lifetime, continuous operation,vehicles and probes that can access distant, cold, dark and inhospitable environments. Missions using nuclear power present better value for money, one mission delivering the science that might only be achieved from several missions using solar power A coherent European approach to nuclear power sources is necessary with options ranging from: Full independence, to structured international cooperation, through to accepting a limited scope in the future.

5 Technology Domains Radioisotope Selection & Production Radioisotope Encapsulation and Aeroshell (RHU & RPS) 2009 to >2015 TRL5 (~ 12-15M) RTG Development Stirling Converter Development

6 European Roadmap Task ) Space Nuclear Power Development Programme (RTG and SRG) 1.1) Isotope Evaluation 1.2) Stirling Engine Requirements 1.3) Small Scale RTG Development to TRL3 (TRP) 1.4) Nuclear Aeroshell and Capsule TRL2-3 (TRP) 1.5) Iridium Alloy Selection and Welding (New Member States - ESA) 1.6) Isotope Production Phase 1 and 2 (MREP) 1.7) Stirling Engine Development Phase 1 (MREP) 1.8) Nuclear Aeroshell, Capsule & Launch Safety TRL4 (MREP) 1.9) Small Scale RTG Development to TRL5 (MREP) 1.10) Stirling Engine Development TRL 6 (MREP) 1.11) Isotope Encapsulation TRL 6 (MREP) 1.12) Small Scale Prototype RTG Development TRL6 (MREP) 1.13) Isotope Production Phase 3? (MREP)

7 UK Activities in Greater Detail

8 RTGs Powered by 241 Am An ESA funded programme of work forming the initial stages of development (TRL3 breadboard) of a European modular RTG device for planetary and deep space applications. Radial Supports Clad Fuel Insulation Thermoelectrics (PbTe, BiTe) Radiator Images Courtesy Of Astrium Clad Fuel Images Courtesy Of Fraunhofer ~50 Welectric TEG ~1 Welectric TEG Heat Source Aeroshell Thermoelectric Generator

9 Encapsulation & Aeroshell Develop a European modular radioisotope containment system that will interface to the RTG and Stirling system but meet the safety requirements for space nuclear power systems. Aeroshell Materials US DOE - Ir Clad Fuel US DOE - GPHS Unit Monteverde Et Al (doi: / j.jeurceramsoc ) Heat Source Metal Matrix Ceramic Matrix Composites

10 Materials & Materials Processing Methods Nano-materials: nano-polycrystalline and carbon nanotube composites, advanced ceramic composites. Improved mechanical properties wear and fracture toughness. Small amounts of carbon nanotube can have a large impact on properties of composites Composites benefits of ceramics plus good electrical and thermal conductivity Anisotropic properties D New envelope of tailored thermo-mechanical properties. Thermoelectrics - Improved efficiency - Enhanced mechanical properties - Terrestrial applications driving development - Self powered safety systems - Small terrestrial RTGs for niche applications - Energy harvesting systems. Conductivity of Alumina = S/m Electrical conductivity of Alumina MWNT (5wt%) + Alumina-Alumina Laminates.

11 European Teams Company/University/Research Lab Astrium UK European Thermodynamics Johnson Matthey Metals Lockheed Martin, UK Nanoforce Ltd National Nuclear Laboratory Queen Mary University of London Reviss UK SEA RAL University of Leicester University of Oxford ESA Programme Development Area/Expertise RTG Development, System Design Thermoelectric Generators Encapsulation & Aeroshell Encapsulation & Aeroshell Encapsulation & Aeroshell; Thermoelectrics; Materials Processing Radioisotope Production; Encapsulation & Aeroshell; Facilities Materials Science Radioisotopes & Transportation of Nuclear Materials Stirling Conversion, Encapsulation & Aeroshell Stirling Conversion RTG Development; Encapsulation & Aeroshell; Materials Science Stirling Conversion France is a major contributor with Areva TA, CNES, SNECMA, University of Nancy and others involved in studies. In Germany, Fraunhofer IPM is contributing to the programme of thermoelectrics development. Luxembourg, Gradel is working on Ir containment with ESA and UK partners.

12 Beyond 2018: Innovative Mission Concepts for Enhanced Science Return

13 Aurora, MREP and Sample Return Mars Robotic Exploration Preparation Image Courtesy Of NASA/JPL Images Courtesy Of ESA Mission Studies Technologies Image Courtesy Of ESA Mars Sample Return Images Courtesy Of ESA & NASA

14 Exploration of Mars...require the sampling of a range of lithologies sedimentary, hydrothermal, and igneous... as well as regolith, dust, atmosphere, depth resolved suite... There is presumably not any single landing site on Mars that could produce all of the samples necessary to support all of the above objectives. How much could be achieved at a single landing site would depend on the magnitude of the rover s mobility and its ability to do scientific sample selection and context documentation. Preliminary Planning for an International Mars Sample Return Mission Report of the International Mars Architecture for the Return of Samples (imars) Working Group June 1, 2008 Innovative mission concepts are needed which can provide: Access to different types of terrain and elevations. Range Mobility Lifetime Sampling Capability Carry complement of scientific instrumentation Preliminary Planning for an International Mars Sample Return Mission, Report of the imars (International Mars Architecture for the Return of Samples) Working Group, 2008,

15 Hopping Across Mars University of Leicester team has been working in collaboration with Astrium UK, Center for Space Nuclear Research, Idaho, USA and more recently RAL Space The Mars Hopper: A vehicle capable of a ballistic hop using in-situ acquired propellants (CO2) is a promising method of achieving increased mobility. At the heart of the engine is a radioisotope heated core. And in addition electrical power would also be provided by RPS. Able to cross terrains inaccessible to rovers. Offer a flexible platform for a variety of different instrument complements and mission scenarios. Focusing on a large vehicle concept, a study was undertaken in the UK: A Mars arrival mass of ~1700 kg. A ~450 kg vehicle with a propellant storage mass of ~50 kg. Capable of travelling in ~1 km hops every 7 sols. ~20 kg science payload (robotic arm). Powered by RTGs/SRGs.

16 Mars Reconnaissance Lander (MRL) Study focused on the Hopper design: Propulsion, power and thermal management Avionics Communications Science payload Landing system Mechanical design/configuration Additional work has been carried out on: The hopper core Materials Performance Outline science mission Planned activities (subject to funding): Compression system and cycle time.

17 MRL: Outline Mission Image (top) (Christensen et al. 2011) and Digital Elevation Model (bottom) (Neukum et al, 2004) based on HRSC imagery of Hypanis Valles/Xanthe Terra region of the ancient highlands. First received attention as one of the potential landing site for the Mars Science Laboratory (Golombek et al., 2011). Evidence for ancient fluvial action in the form of the main channel and deltaic formations in the region (Hauber et al., 2009). The blue square centred around 11.4 o N, o E is 180 km x 180 km. The black line is a ~200 km traverse for the Hopper. Elevation along this ranges from -3 to >0 km MOLA. 1. Landing site taken to be 20 km in diameter consistent with new SkyCrane technology. Thus landing occurs in a safe area of low elevation region within a smooth, eroded crater. 2. Delta which will show sediments deposited from water into standing water. 3. Region of recent periglacial activity. 4. Final traverse up main channel to 5. Christensen et al., 2011, HEMIS Public Data Releases, PDS node, Arizona State Univ., Neukum et al., 2004, HRSC: The High Resolution Stereo Camera of Mars Express, in Mars Express: The scientific payload, edited by A. Wilson, pp , ESA, Noordwijk, The Netherlands Hauber et al, 2009, Sedimentary deposits in Xanthe Terra: Implications for the ancient climate on Mars. Planetary and Space Science, 57, Golombek, M., et al., 2011, Final four landing sites for the Mars Science Laboratory (expanded abstract): 42nd Lunar and Planetary Science, Abstract #1520, LPSC, Houston (CD-ROM).

18 MRL: Science Payload Instrument Description ~Mass (kg) ~Power (W) Gas Analysis Analysis of volatiles Stereo Camera Visual record of landing site XRF XRD Mineralogy & composition Mossbauer Elemental composition Microscope Visual inspection Corer Grinder Sample preparation Environment Sensors Environmental information and context Robotic Arm Surface contact TOTAL

19 Final Remarks Full development programme with significant UK involvement. Challenging technology development goals and launch safety requirements. Long term benefits in more capable spacecraft, continuous operation,vehicles and probes that can access distant, cold, dark and inhospitable environments. Terrestrial applications. Technology transfer from non-space sector. A coherent European approach to developing nuclear power sources will need to be adaptable to technology development challenges as they arise.

20 Acknowledgements Dr D. Parker, Mrs S. Horne, Dr M. Chahal UK Space Agency, Swindon, UK Dr R. Cordy Astrium, UK Prof G. Fraser, Prof M. Sims, Prof M. Lester University Of Leicester, Space Research Centre, Leicester, UK Dr K. Stephenson, Dr M. Ditter, Dr A. Chicarro, Dr H. Schroeven-Deceunink ESA

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