Nuclear propulsion

Integrated system health management (ISHM) technologies have been developed to address safety, replace time-based maintenance with condition-based maintenance, and to reduce life cycle costs. Traditional space system designs have focused on safety to minimize the risk to crew and to protect the public, astronauts and pilots, the NASA workforce, and high-value equipment and property. Systems have relied on high reliability components to provide the necessary safety margins and avoid operational mission failures. The current vision for future manned and unmanned space missions to the International Space Station, the Moon, Mars, and beyond, will require longer duration missions and will rely on complex assemblages of components. Increased mission duration and complexity increase the probability of operational mission failures that must be mitigated without jeopardizing safety or the objectives of the current or future missions that might reuse critical mission components. ISHM technology will be essential for providing near-real-time assessments of system capability, safety margins, and maintenance and sustainment requirements. The Applied Research Lab has conducted a series of workshops for NASA which focused on defining requirements for integrated system health monitoring and for the integration of health monitoring and control to provide intelligent self situational awareness (ISSA). The results of these workshops indicate that the benefits of ISHM and greater integration between ISHM and control include increased safety and mission assurance, the ability to rapidly respond to system failures, and decreased operator workload. Emerging open system standards such as OSA-EAI provide a framework for integrating system health monitoring with control functionality in spacecraft avionics systems. The purpose of this paper is to describe areas where system health monitoring can impact safety, reliability and sustainment in space applications and present the results of workshops conducted for NASA to identify requirements for the integration of health monitoring and control in future space systems

With the perspective of future space exploration missions that are more challenging than those conducted so far, the assessment of the radiative heating to the vehicles entering a planetary atmosphere at a high speed requires thorough studies. In the framework of such future missions, ESA has revived the study of radiation of non-equilibrium plasmas [1]–[4]. As a space vehicle travels at very high speed, when it enters an an atmosphere it is slowed down by the friction to the more and more dense layers of atmosphere. Also, because of the very high velocity of the vehicle a strong shock wave develops in front of the vehicle. The shock wave is usually detached from the vehicle surface because of the blunt shape of its heat shield. Through the shock wave, the kinetic energy is transferred into thermal energy leading to the excitation and the dissociation of the molecules and even to the ionization and the radiation of the gas mixture in the shock layer, depending of the temperature and of the gas composition.

Protecting Lunar Colonies From Space Radiation

Amateur astronomy of the Solar System is living a golden age with major contributions to modern planetary science. These contributions cover a wide spectrum of topics that range from the discovery of impacts in Jupiter [1-2], to the observation of stellar occultations by minor bodies [3-4], the characterization of unexpected high-atmospheric events in Mars [5], or the characterization of giant storms on Jupiter [6] and Saturn [7-8]. Besides these examples of high-profile publications, there is an increasing number of amateur contributions to dozens of studies of planetary atmospheres and countless contributions to the study of minor bodies. While we focus here in the role of amateur astronomy observations of planetary atmospheres, we also recognize the varied and healthy professional and amateur collaborations in other areas of solar system astronomy.The reasons behind this golden age lie in the two sides of the collaboration: On the side of amateur astronomers, many of them use very efficient detectors and advanced software tools, and they are highly connected at an international level. Thus, they provide high-quality observations on a regular basis to professional astronomers, or have strong analysis teams like the JUPOS team as an example (http://jupos.privat.t-online.de/index.htm). These frequent amateur observations provide essential monitoring of the temporal evolution of planetary atmospheres. On the other side, professional astronomers are aware of the potential of these observations and actively seek the collaboration of amateur astronomers and citizen scientists. A key case in this regard is NASA’s Juno mission to the giant planet Jupiter, and its large-scale collaboration around the JunoCam instrument on the mission Juno website: https://www.missionjuno.swri.edu/. The mission has been recently extended until 2025 and details of the contribution of amateur observers to this new mission scenario are presented by Orton et al. in session ODAA5 in this meeting. Other examples of professionals seeking a global collaboration with amateurs are the various professional and amateur astronomy services and workshops organized by research projects like the Europlanet 2020 Research Infrastructure (2016-2019) and Europlanet 2024 Research Infrastructure (2020-2024).We anticipate that the trend of amateur astronomy playing an important role in providing additional data sets to space missions will continue to grow and we advocate for the early establishment of such collaborations.  We review some of the elements that have made the collaboration of amateur astronomers with the Juno mission so fruitful for both parties and how this collaboration has grown beyond Jupiter into enhanced collaborations in other fields through networking amateur astronomers and providing a successful example to other fields.We also discuss future ground-based high-resolution amateur observations of Solar System planets in support of future missions. These include the James Webb Space Telescope observations of planets (launch in October 2021), ESA’s Jupiter Icy moons Explorer (JUICE, launching in 2022) and NASA’s Europa Clipper missions to the Jupiter system in the early 2030s, the in situ exploration of Saturn’s moon Titan by the Dragonfly mission (NASA) in 2034, the Envision mission to Venus (if selected by ESA), and possible future missions to the Icy Giants Uranus and Neptune. Each of these ambitious missions will benefit from the strong partnership between amateur and professional planetary scientists. The first in this line is the JWST observations of Giant planets to be conducted in 2022 (see Fletcher et al. in session OPS3 in this conference).Finally, we also show some professional and amateur networking elements developed under the umbrella of the Europlanet projects, including the recently launched Europlanet Telescope Network (https://bit.ly/2Br5LDt), and we present possible scenarios for future pro-am collaborations beyond the end of the Europlanet 2024 project. AcknowledgementsPart of this research has been supported by Europlanet 2024 RI. Europlanet 2024 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871149.

Sample return from asteroids and comets beyond the main belt is considered to be one of the most worthwhile future deep space missions [1]. Japan Aerospace Exploration Agency (JAXA) is currently entertaining a Jupiter Trojan sample return mission using a solar power sail [2], following the heritage of the Hayabusa sample return mission [3]. Because of high orbital energy corresponding to outer bodies, a sample return capsule (SRC) for such a future mission is expected to reenter the Earth’s atmosphere at velocities higher than 14 km/s and, hence, to encounter much severer aerodynamic heating environments than those of any past SRCs. Especially, the radiative heat transfer is considered to play a significant role in heat transfer processes in the shock layer, since the radiative heat transfer exponentially increases with the atmospheric flight velocity. To optimize the aerothermal design of the SRC and to minimize the mass of the thermal protection system (TPS) equipped with the SRC aeroshell, it is essentially required to accurately predict the aerothermal environments around the SRC along the reentry trajectory.

Formation °ying spacecraft has been identied as an enabling technology for many future NASA and DoD space missions. However, this is still, as yet, an unproven technology. Thus, to minimize the risk associated with using this new technology on future missions, testbeds are required that enable a com- prehensive simulation and validation. This paper presents an innovative hardware-in-the-loop testbed that can be used to analyze estimation and control architectures for formation °ying spacecraft. The testbed consists of multiple computers that each em- ulate a spacecraft in the °eet. These computers are restricted to communicate via serial cables to emu- late the actual inter-spacecraft communications ex- pected on-orbit. All estimation and control algo- rithms are implemented in MATLAB, which greatly enhances its °exibility/recongurability and provides an excellent environment for rapidly comparing nu- merous control and estimation algorithms and ar- chitectures. A multi-tasking/multi-thread software environment is simulated by simultaneously running several instances of MATLAB on each computer. The paper presents the initial simulation results us- ing a highly distributed estimation, coordination, and control architecture for a °eet of 4 spacecraft.

Future applications of miniaturized space systems will have special needs on MEMS components. This paper addresses the needs, status and perspectives of the MEMS technology for miniaturized space system from the perspective of a spacecraft developer. First, the needs of future space missions on MEMS components are discussed. Then, the state-of-the- art MEMS technologies are reviewed based upon these needs. Finally, perspectives of space-based MEMS technology will be addressed based on the analysis of both future mission needs and technological trends.

One major factor for operational safety and planning of human extravehicular activities (EVAs) is the topography of the landing region. During planning for EVAs for future crewed missions, digital elevation models (DEMs) and derived slope maps are often used to place constraints on proposed EVA paths to minimize the slopes and vertical meters traveled. However, the specification of these constraints has not yet been studied in detail and has to date relied on generalized assumptions. The Apollo program was the subject of meticulous planning and execution over an extended period. Our study concentrated on the pivotal aspect of mission planning, namely the topographic conditions of all Apollo landing sites. Furthermore, there are numerous conditions of lunar exploration whose "ground truth" can only be fully comprehended by astronauts who have personally visited the Moon. Certainly, there are technical constraints for the use and operation of equipment and tools, such as suits and instrument carts. However, astronaut observational physiological and psychological experiences and constraints are need to be considered for the planning of successful EVAs. In this study, we examined a variety of data sources, including topographic data, Apollo astronaut reports, audio and video recordings, in order to assess their experience and performance in relation to the topography and slopes along each Apollo extra vehicular activity (EVA). The ability of the astronauts to accurately perceive distances, slopes, and to move with confidence is contingent upon topographic and illumination conditions, as well as the specific equipment that they are required to carry. Future mission planning must take realistic traverse speeds into account, as well as the perception of both real and perceived hazards on challenging traverses.

Planetary protection is one of the key problems which will greatly affect the future human missions to Mars. Planetary protection has three major goals:1)The protection of extraterrestrial planet from terrestrial life contamination (forward contamination prevention);2) The protection of Earth from extraterrestrial life (back contamination prevention);3) The protection of the health and safety of astronauts. The international aerospace community has begun to formulate policies and conduct technical discussions on planetary protection for human Mars missions. In this review,the definition and legal base of planetary protection are introduced,and the planetary protection implementation of NASA Apollo program is reviewed,and the major contaminants,contamination pathway,and contamination control strategy for future human Mars missions are discussed.

The establishment of sustained human presence on the Moon for science and exploration combines the design, integration, and operation challenges experienced from both the short Apollo lunar missions and the build-up and sustained crew operations of the International Space Station (ISS). With the goal of establishing a lunar Outpost on the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth’s economic sphere, a change in how both the Apollo and ISS Programs were planned and executed is required for this new international lunar exploration program. Since the Vision for Space Exploration (VSE) was released in 2004, NASA, in conjunction with international space agencies, industry, and academia, has continued to define and refine plans for sustained and affordable robotic and human exploration of the Moon and beyond. One area NASA is developing that can significantly change how systems required for sustained human presence are designed and integrated, as well as potentially break our reliance on Earth supplied logistics, is In-Situ Resource Utilization (ISRU). ISRU, also known “living off the land”, involves the extraction and processing of local resources into useful products. In particular, the ability to make propellants, life support consumables, fuel cell reagents, and radiation shielding can significantly reduce the cost, mass, and risk of sustained human activities beyond Earth. The ability to modify the lunar landscape for safer landing, transfer of payloads from the lander to an outpost, dust generation mitigation, and infrastructure placement and buildup are also extremely important for longterm lunar operations. Because ISRU hardware and systems have never been demonstrated before, NASA is examining how these capabilities can be added into mission designs and plans such that lunar mission success is currently not relying on these capabilities, but that the systems developed are flexible enough to incorporate the capabilities once they have been demonstrated. With this in mind, the ISRU Project within the Exploration Technology Development Program (ETDP) has initiated development and testing of hardware and systems in three main focus areas: (1) Regolith Excavation, Handling and Material Transportation; (2) Oxygen Extraction from Regolith; and (3) ISRU Precursor Activities. To minimize cost and ensure that ISRU technologies, systems, and functions are integrated properly into the Outpost, technology development efforts are being coordinated with other ETDP development areas such as Surface Mobility, Surface Power, Life Support, EVA, and Propulsion, as well as outside government agencies, industry, academia, and International Partners to the maximum extent possible to leverage funding and increase commonality of hardware at the Outpost. Lastly, laboratory and field system-level tests and demonstrations will be performed as often as possible to demonstrate improvements in: Capabilities (ex. 1 ISRU Project Manager for ETDP, EP, and AIAA Member 2 Chief, Applied Science Division, KT-D-2, and AIAA Member 3 ISRU Lead for Excavation, MS 77-5, and AIAA Member 4 Deputy for ISRU Development Support, VP33, and AIAA Member AIAA SPACE 2008 Conference & Exposition 9 11 September 2008, San Diego, California AIAA 2008-7853 Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes. All other rights are reserved by the copyright owner. American Institute of Aeronautics and Astronautics 2 digging deeper); Performance (ex. lower power); and Duration (ex. more autonomy or more robustness), as well as form the partnerships with industry and International Partners that will be needed once actual Outpost flight hardware development and deployment begins. This paper will provide the status of work performed to date within the NASA ISRU Project with respect to technology and system development and field demonstration activities, as well as the current strategy to implement ISRU in future robotic and human lunar exploration missions.

Like previous missions to the outer planets, future spacecraft missions such as Pluto/Kuiper Express, Europa Orbiter, and Solar Probe will require radioisotope power systems for their long voyages away from the Sun. Several candidate advanced power conversion technologies have been proposed that have been proposed that have higher power conversion efficiencies than the traditional thermoelectric generators, with the potential for reduced mass and reduced quantities of nuclear fuel required. Studies conducted by Lockheed Martin under the direction of the Department of Energy have included the development of system conceptual designs utilizing Alkali Metal to Electric Conversion (AMTEC) and Stirling power conversion. Generator concepts based on these conversion technologies are compared in this paper with an alternative Small RTG, based on the General Purpose Heat Source—Radioisotope Thermoelectric Generator (GPHS-RTG).

Since the launch of the first radioisotope power system (RPS) on Transit 4A in 1961, numerous research and development activities have been performed centered on increasing the overall thermal to electrical conversion efficiency of the selected nuclear fueled power system. The latest U.S. fielded RPS (MMRTG - Multi-Mission Radioisotope Thermoelectric Generator) contains eight GPHS (General Purpose Heat Source) modules which nominally yield ∼2000W Th from the thirty-two 238PU5O 2 ceramic fuel pellets. MMRTG's PbTe/TAGS-85 based thermoelectric couples have a thermal to electrical conversion efficiency of ∼5.5% thus yielding ∼110W e at launch. This paper centers on the discussion of a conceptual idea that entails employing a second set of thermoelectrics on an MMRTG. These would be employed for possibly converting a portion of the excess “waste heat” (∼1750 W th ) into additional electrical mission power. First-order experiments and calculations employing bismuth telluride (Bi 2 Te 3 ) based thermoelectric modules being considered for a European RPS by the University of Leicester indicate that an improvement in the efficiency of an MMRTG could be achieved by integrating them with the PbTe/TAGS-85 thermoelectrics being utilized in the MMRTG in a “dual” or “cascaded” arrangement. This arrangement of two different integral thermoelectric materials suggests the intriguing possibility of the additional harvesting of a portion of the MMRTG's currently unutilized “waste heat”. This appears to be feasible since the cold side temperature of the PbTe/TAGS-85 in an MMRTG is ∼200°C which corresponds to typical hot-side operating temperatures of the Bi 2 Te 3 thermoelectric modules. It is recognized that extensive thermo-mechanical-electrical design, modeling, and analysis are required to fully investigate the cascaded thermoelectric concept. In addition, materials compatibility and assembly aspects will need to be fully addressed in the future. The present work indicates that system-level performance gains could be achieved via a “cascaded” or cMMRTG which could result in electrical power increases at BOM (Beginning of Mission) of up to ∼25%, and perhaps more significantly, gains in EODL (End of Design Life) power of up to ∼40% which could be utilized on a future space mission.

The U.S. Navy recently conducted an analysis of alternatives (AOA) to set the stage for determining the characteristics and acquisition strategy for its next generation aircraft carrier. The platform design selected is expected to be in service throughout the 21st century. The parameters under consideration for change in the new carrier design lie in the areas of propulsion and electric power generation, aviation, survivability, service life, and total ownership cost (TOC) reduction. The issue of affordability is paramount This paper focuses on the need for the program management office and its supporting cost analysis staff to understand the life cycle cost (LCC) of the existing and proposed future aircraft carriers and to then translate these LCC's into meaningful information for cost‐conscious decision making. The challenge is to relate the LCC in terms the key decision‐makers and the engineering team can use to satisfy their respective roles. Thus, it is necessary to translate the results of the given ship design alternative LCC's into the paradigms of the respective stakeholders: Fleet User (operators of aircraft carriers) Ship Designers (translators of the fleet operator requirements) Program Sponsors (providers of the funding resources) Program Management Office, Shipbuilder and Supporting Industry (executors of the acquisition and construction of the ship) Navy and OSD decision‐makers (overseers of program execution) The paper describes the aircraft carrier LCC breakdown structure that has resulted, in part from a recent navy/shipbuilder integrated product team effort to capture total ownership costs. The structure has been used in the AOA as a tool to identify cost drivers and to add the time element to the cost equation in order to perform return on investment and program affordability analysis. The expanded ship work breakdown structure (ESWBS) has emerged as the central backbone of the cost work breakdown for AOA work. The ESWBS structure is a natural choice as it is the framework within which the design and engineering community works, it forms the basis of weight estimating for ships, and it has been widely used in ship acquisition cost estimating for years. In addition, the ESWBS provides perhaps the best framework from which to relate to program requirements, as it describes the ship by ship system. The approach, for the first time, provides a breakdown of the operating and support (O&S) cost elements by ESWBS. From this nucleus structure, it is possible to present costs in other required formats such as the: Office of Secretary of Defense (OSD) cost analysis improvement group (CAIG) summary level LCC categories, by ship capability or design feature, and by cost driver hierarchy.

Chang’e 3 lunar mission and upper limit on stochastic background of gravitational wave around the 0.01 Hz band

High power and high voltage applications are a major requirement in the future space missions. The feasibility and efficiency of these systems are currently limited by the space qualified silicon semiconductors, so silicon carbide devices are proposed to overcome the said limitations. However, silicon carbide needs to be operated in specific conditions to be safe to use in space applications. In addition, there are no space qualified drivers for silicon carbide and industry is hesitant to redesign completely their systems. This work proves silicon carbide MOSFETs can be used with space qualified drivers, while operating in safe operating conditions for space and still obtaining performance benefits when compared to space qualified silicon MOSFETs. To ensure the accuracy of the comparison, conduction and switching losses are directly measured in the analyzed devices, in an identical laboratory setup and space operation conditions specially designed for this work. The paper also shows how the achieved loss reduction can be used in specific space applications. The article proves silicon carbide MOSFETs are an enabling technology for efficient high-power applications in space, using well-known space qualified drivers and without having to redesign the systems.