Dual-mode Propulsion System Enabling Cubesat Exploration of the Solar System

It is apparent the cost of planetary exploration is rising as mission budgets are declining. Currently small scientific beds geared to performing limited tasks are being developed and launched into low earth orbit (LEO) in the form of small-scale satellite units, i.e., CubeSats. These micro- and nano-satellites are gaining popularity among the university and science communities due to their relatively low cost and design flexibility. To date these small units have been limited to performing tasks in LEO utilizing solar-based power. If a reasonable propulsion system could be developed, these CubeSat platforms could perform exploration of various extra-terrestrial bodies within the solar system engaging a broader range of researchers. Additionally, being mindful of mass, smaller cheaper launch vehicles (~1,000 kg to LEO) can be targeted. This, in effect, allows for beneficial exploration to be conducted within limited budgets.Researchers at the Center for Space Nuclear Research (CSNR) are proposing a low mass, radioisotope-based, dual-mode propulsion system capable of extending the exploration realm of these CubeSats out of LEO.The proposed radioisotope-based system would leverage the high specific energies [J/kg] associated with radioisotope materials and enhance their inherent low specific powers [W/g]. This is accomplished by accumulating thermal energy from nuclear decay within a central core over time. This allows for significant amounts of power to be transferred to a flowing gas over short periods of time. In the proposed configuration the stored energy can be utilized in two ways: (1) with direct propellant injection to the core, the energy can be converted into thrust through the use of a converging-diverging nozzle and (2) by flowing a working fluid through the core and subsequent Brayton engine, energy within the core can be converted to electrical energy. The first scenario achieves moderate ranges of thrust, but at a higher Isp than traditional chemical-based systems. The second scenario allows for the production of electrical power, which is then available for electric-based propulsion. Additionally, once at location the production of electrical power can be dedicated to the payload's communication system for data transfer. Ultimately, the proposed dual-mode propulsion platform capitalizes on the benefits of two types of propulsion methods the thrust of thermal propulsion ideal for quick orbital maneuvers and the specific impulse of electric propulsion ideal for efficient interplanetary travel. Overall, the system is functioning as a radioisotope thermal rocket (RTR).In this study the RTR concept is being developed as an in-space propulsion system to deliver a 6U CubeSat payload to the orbit of the Saturnian moon - Enceladus. Additionally, this study will develop an entire mission architecture for Enceladus targeting a total allowable launch mass of 1,000 kg

History of Resistance Welding Oxide Dispersion Strengthened Cladding and other High Temperature Materials at Center for Advanced Energy Studies

Research proposal 08-1079, 'A Comparative Study of Welded ODS Cladding Materials for AFCI/GNEP,' was funded in 2008 under an Advanced Fuel Cycle Initiative (AFCI) Research and Development Funding Opportunity, number DE-PS07-08ID14906. Th proposal sought to conduct research on joining oxide dispersion strengthen (ODS) tubing material to a solid end plug. This document summarizes the scientific and technical progress achieved during the project, which ran from 2008 to 2011

History of Resistance Welding Oxide Dispersion Strengthened Cladding and other High Temperature Materials at Center for Advanced Energy Studies

Research proposal 08-1079, 'A Comparative Study of Welded ODS Cladding Materials for AFCI/GNEP,' was funded in 2008 under an Advanced Fuel Cycle Initiative (AFCI) Research and Development Funding Opportunity, number DE-PS07-08ID14906. Th proposal sought to conduct research on joining oxide dispersion strengthen (ODS) tubing material to a solid end plug. This document summarizes the scientific and technical progress achieved during the project, which ran from 2008 to 2011

Community Sport Service Provision, Resident Satisfaction, and Participation

Advocating for the “gold medal strategy”, China has made great advancements in elite sports; however, the significant achievement in elite sports has not translated into the development of mass sport participations. To form a stronger foundation of a sport pyramid, more attention should be directed to community sports and promoting healthy lifestyles. The purpose of this study was to examine the impact of community sport service provisions on participants’ satisfaction and in turn on their sport participation behavior. In the current study, the public sport service in community includes sport facilities, sport organizations, sport programs, fitness test, and volunteer services (fitness guide). According to the hierarchy of effects model of Lavidge and Steiner (1961), both hard services and soft services were hypothesized to exert positive influences on consumer satisfaction and participation behavior in community sport (i.e., payment and participation frequency). Of the 750 copies distributed in Guangdong, China, 576 valid questionnaires were completed and returned, yielding a usable response rate of 76.8%. The first half of the sample was used to conduct exploratory factor analyses (EFA) for the provision items; the second half was used to conduct confirmatory factor analyses (CFA) of these two measures and also conduct a structural equation modeling (SEM) analysis to examine the relationships among public service provision, consumer satisfaction, and consumption behavior in community sports. The results of EFA and CFA indicated that five aspects of community sport service provision could be categorized into hard service and soft services. Specifically, hard refers to sport facility, organization building and organizing activity which can be seen and touched while soft service refers to fitness test, fitness instruction and sport information which sometimes are intangible. The results of SEM suggested that hard service provision positively influenced consumer satisfaction (β = .685, p \u3c .01), whereas soft service provision did not exert significant influence on consumer satisfaction (β = .210, p \u3e .05). Satisfaction would positively impact the frequency of participation was supported (β = .212, p \u3c .01). Consumer satisfaction would positively impact the level of payment for participating in sport organizations was rejected (β = -.298, p \u3c .01). In conclusion, the present study provided empirical evidence that hard sport service in community, as measured by the sport facility, grassroots sport organization and sport activity program, is an important element of the public sport service construct in the context of community sports. Furthermore, it highlighted that these programs have had a strong influence on resident satisfaction and participation behavior. The resulting theoretical framework is therefore applicable in this context. Lastly, the results revealed the important role of satisfaction in the prediction of residents’ future behaviors. By understanding the major drivers of residents’ behaviors, local sport councils, community managers, grassroots organizations, and residents could work together to establish a nonhierarchical and cooperative mechanism that facilitates sport participation

Development of a propulsion system and component test facility for advanced radioisotope powered Mars Hopper platforms

Verification and validation of design and modeling activities for radioisotope powered Mars Hopper platforms undertaken at the Center for Space Nuclear Research is essential for proof of concept. Previous research at the center has driven the selection of advanced material combinations; some of which require specialized handling capabilities. The development of a closed and contained test facility to forward this research is discussed within this paper

Development of the Variable Atmosphere Testing Facility for Blow-Down Analysis of the Mars Hopper Prototype

Recent developments at the Center for Space Nuclear Research (CSNR) on a Martian exploration probe have lead to the assembly of a multi-functional variable atmosphere testing facility (VATF). The VATF has been assembled to perform transient blow-down analysis of a radioisotope thermal rocket (RTR) concept that has been proposed for the Mars Hopper; a long-lived, long-ranged mobile platform for the Martian surface. This study discusses the current state of the VATF as well as recent blow-down testing performed on a laboratory-scale prototype of the Mars Hopper. The VATF allows for the simulation of Mars ambient conditions within the pressure vessel as well as to safely perform blow-down tests through the prototype using CO2 gas; the proposed propellant for the Mars Hopper. Empirical data gathered will lead to a better understanding of CO2 behavior and will provide validation of simulation models. Additionally, the potential of the VATF to test varying propulsion system designs has been recognized. In addition to being able to simulate varying atmospheres and blow-down gases for the RTR, it can be fitted to perform high temperature hydrogen testing of fuel elements for nuclear thermal propulsion

Additive Manufacturing for Energy: A Review

The conflict between rapidly growing global energy demand and climate change is a grand challenge that requires significant science and technology innovations. Advanced manufacturing could extensively drive down greenhouse gas emission and pollution, and shorten the time-to-market. Additive manufacturing is a process of fabricating three-dimensional objects by depositing materials layer-by-layer directly from computational geometry model, and it eliminates the design and fabrication restrictions of conventional manufacturing methods to a large extent. As an emerging and transformative technology, additive manufacturing technologies have shown the potential benefits of energy saving in multiple energy sectors. To further increase their applications in nuclear energy and renewable energies, fundamental research is needed to overcome some key challenges in terms of process monitoring and control, dimension accuracy, and structural integrity of the components. The validation and qualification of additive manufacturing processes and the products from those additive manufacturing processes are imperative to meeting the high standards of critical components in various energy production, conversion and storage systems. In this review article, we summarize the current status of cutting-edge additive manufacturing technologies and their applications in the fields of nuclear energy, battery, fuel cell, oil & gas. We also outline the major challenges and fundamental research needed to achieve the full potential of additive manufacturing technologies. This review provides critical discussion and prospects to address global energy challenges by applying innovative additive manufacturing technologies

Current Development of Nuclear Thermal Propulsion technologies at the Center for Space Nuclear Research

Nuclear power and propulsion has been considered for space applications since the 1950s. Between 1955 and 1972 the US built and tested over twenty nuclear reactors / rocket engines in the Rover/NERVA programs1. The Aerojet Corporation was the prime contractor for the NERVA program. Modern changes in environmental laws present challenges for the redevelopment of the nuclear rocket. Recent advances in fuel fabrication and testing options indicate that a nuclear rocket with a fuel composition that is significantly different from those of the NERVA project can be engineered; this may be needed to ensure public support and compliance with safety requirements. The Center for Space Nuclear Research (CSNR) is pursuing a number of technologies, modeling and testing processes to further the development of safe, practical and affordable nuclear thermal propulsion systems

Spark Plasma Sintering of Fuel Cermets for Nuclear Reactor Applications

The feasibility of the fabrication of tungsten based nuclear fuel cermets via Spark Plasma Sintering (SPS) is investigated in this work. CeO2 is used to simulate fuel loadings of UO2 or Mixed-Oxide (MOX) fuels within tungsten-based cermets due to the similar properties of these materials. This study shows that after a short time sintering, greater than 90 % density can be achieved, which is suitable to possess good strength as well as the ability to contain fission products. The mechanical properties and the densities of the samples are also investigated as functions of the applied pressures during the sintering

The Mars Hopper: a radioisotope powered, impulse driven, long-range, long-lived mobile platform for exploration of Mars

Planetary exploration mission requirements are becoming more demanding. Due to the increasing cost, the missions that provide mobile platforms that can acquire data at multiple locations are becoming more attractive. Wheeled vehicles such as the MER rovers have proven extremely capable but have very limited range and cannot traverse rugged terrain. Flying vehicles such as balloons and airplanes have been proposed but are problematic due to the very thin atmospheric pressure and the strong, dusty winds present on Mars. The Center for Space Nuclear Research has designed an instrumented platform that can acquire detailed data at hundreds of locations during its lifetime - a Mars Hopper. The Mars Hopper concept utilizes energy from radioisotopic decay in a manner different from any existing radioisotopic power sources—as a thermal capacitor. By accumulating the heat from radioisotopic decay for long periods, the power of the source can be dramatically increased for short periods. The platform will be able to "hop" from one location to the next every 5-7 days with a separation of 5-10 km per hop. Preliminary designs show a platform that weighs around 52 kgs unfueled which is the condition at deployment. Consequently, several platforms may be deployed on a single launch from Earth. With sufficient lifetime, the entire surface of Mars can be mapped in detail by a couple dozen platforms. In addition, Hoppers can collect samples from all over the planet, including gorges, mountains and crevasses, and deliver them to a central location for eventual pick-up by a Mars Sample Return mission. The status of the Mars Hopper development project at the CSNR is discussed