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Combinations of nuclear thermal propulsion (NTP), nuclear electric propulsion (NEP), and chemical propulsion are discussed. Technical details are given in viewgraph form. The characteristics of each configuration are discussed, particularly thrust characteristics.
Using chemical and nuclear electric propulsion for the exploration of the Martian moons will be investigated. Both oxygen/hydrogen chemical propulsion and nuclear electric propulsion with 500 kilowatt electric (kWe) to 10 megawatt electric (MWe) reactors will be assessed. The initial masses, propellant masses, and trip times for a variety of space vehicle payload masses will be compared. For high energy orbital transfer, the nuclear electric propulsion vehicles required a small fraction of the propellant mass over oxygen/hydrogen orbital transfer vehicles (OTVs). The moons, Phobos and Deimos, may hold resources for refueling future space vehicles. In-situ resource utilization (ISRU) can be a powerful method of reducing Earth dependence on space vehicle propellants, liquid water, and breathing gases. Historical studies have identified the potential of water in carbonaceous chondrites on the moons. The moon-derived propellants OTVs that move payloads between the moons and to other important operational Mars orbits. Also, the propellants have been suggested to support reusable Mars landers. To extract the water, the mined mass, its volume and the mining time were estimated. The water mass fraction may be as low as 2x10 −4 . Very large masses were needed to be extracted for up to 100 MT of water.
A method was developed of lowering the cost of planetary exploration missions by using an electromagnetic propulsion/launcher, rather than a chemical-fueled rocket for propulsion. An electromagnetic launcher (EML) based at the International Space Station (ISS) would be used to launch small science payloads to the Moon and near Earth asteroids (NEAs) for the science and exploration missions. An ISS-based electromagnetic launcher could also inject science payloads into orbits around the Earth and perhaps to Mars. The EML would replace rocket technology for certain missions. The EML is a high-energy system that uses electricity rather than propellant to accelerate payloads to high velocities. The most common type of EML is the rail gun. Other types are possible, e.g., a coil gun, also known as a Gauss gun or mass driver. The EML could also "drop" science payloads into the Earth's upper
Electrostatic energy storage (EES) capacitors are critical for renewable energy and high-power systems, driving the search for dielectric materials that combine superior electrical insulation, mechanical flexibility, low density, cost-effectiveness, and processability. Polymer-based dielectrics have emerged as leading candidates, particularly for high electric field applications. However, conventional polymers often fail to meet the demands of high-temperature environments due to increased electrical conductivity and reduced discharged energy density at elevated temperatures, resulting in energy loss and reduced performance. High glass transition temperature (T g) polymers show promise but require further optimization to enhance their energy storage capabilities under thermal and electrical stress. This review provides a comprehensive update on recent advancements in high-T g polymer-based dielectrics for EES capacitors, focusing on both intrinsic polymers and all-organic composites. It outlines key design principles, critical performance parameters, and innovative strategies—such as nanofiller doping, layered architectures, physical blending, and chemical crosslinking—to improve electrical, thermal, and mechanical properties. The review also highlights emerging trends, including the integration of machine learning algorithms to explore novel polymer structures and expand the chemical design space. By bridging the gap between academic research and industrial application, this review aims to accelerate the development of next-generation dielectric materials capable of balancing multiple performance metrics for high-temperature EES capacitors.
Spatial and energy resolutions of state-of-the-art transmission electron microscopes (TEMs) have surpassed 50 pm and 5 meV. However, with respect to the time domain, even the fastest detectors combined with the brightest sources may only be able to reach the microsecond timescale. Thus, conventional methods are incapable of resolving myriad fundamental ultrafast (i.e., attosecond to picosecond) atomic-scale dynamics. The successful demonstration of femtosecond (fs) laser-based (LB) ultrafast transmission electron microscopy (UEM) nearly 20 years ago provided a means to span this nearly 10-order-of-magnitude temporal gap. While nanometer-picosecond UEM studies of dynamics are now well established, ultrafast Å-scale imaging has gone largely unrealized. Further, while instrument development has rightly been an emphasis, and while new modalities and uses of pulsed-beam TEM continue to emerge, the overall chemical and materials application space has been only modestly explored to date. In this Perspectives article, we argue that these apparent shortfalls can be attributed to a simple lack of data and detail. We speculate that present work and continued growth of the field will ultimately lead to the realization that Å-scale fs dynamics can indeed be imaged with minimally modified UEM instrumentation and with repetition rates (f rep ) below - and perhaps even well below - 1 MHz. We further argue that use of low f rep , whether for LB UEM or for chopped/bunched beams, significantly expands the accessible application space. Furthermore, this calls for systematically establishing modality-specific limits so that especially promising technologies can be pursued, thus ultimately facilitating broader adoption as individual instrument capabilities expand.
Pathfinder is a research and technology project, initiated by NASA in 1989 to support the U.S. civil space program studies for the preparation for future space exploration missions. This paper describes the goals and objectives, the management, the technical plan, and technology transfer for the Chemical Transfer Propulsion program, which is a key element of one of the four programmatic thrusts (the Space Transfer) of the Pathfinder. The Chemical Transfer Propulsion will provide the technology for high-performance liquid oxygen/liquid hydrogen expander cycle engines for space-based transfer vehicles as well as for lunar and Mars landers.
Chart on launch vehicles and chemical propulsion for educational display
Perovskite oxides continue to attract huge interest due to their fascinating and wide-ranging properties for diverse applications. The tunability of these properties may be further enhanced by increasing their compositional complexity via double perovskite-ordered configurations containing multiple cations. In this work, we focus on an exhaustive chemical space of single and double oxide perovskites and optimally explore this space to identify novel compositions that are likely to form stable compounds. Critically, we examine the relationship between formability, the practical ability to synthesize a compound, and stability, the thermodynamic preference to form the structure. Our formability and stability training data sets were enumerated from the available experimental literature and in-house density functional theory computations and contained 1505 and 3469 examples, respectively, representing state-of-the-art in the current open literature in perovskite and double perovskite compounds. Subsequently, cross-validated and highly accurate machine learning classification models are built using these training data sets and employed to screen for novel stable oxide perovskites. The study identifies (1) atomic features relevant to prediction of formability and stability in perovskite and double perovskite compounds, (2) the importance of including energy contributions due to local structural relaxations going beyond the high symmetry perovskite phase, and (3) 437,828 double perovskite compounds that are likely to be stable and 891,188 compounds that are likely to be formable. From the intersection of this large chemical space of formable and stable oxide perovskites, 414 compositions are identified as the most promising candidates for future experimental synthesis of novel oxide perovskites. The developed models may be generalized and have implications beyond perovskite discovery if applied to other families of compounds.
Space power requirements for SEI are reviewed, including the results of a NASA 90-day study and reports by the National Research Council, AIAA, NASA, the Advisory Committee on the Future of the U.S. Space Program, and the Synthesis Group. The space power requirements for the SEI robotic missions, lunar spacecraft, Mars spacecraft, and human missions are summarized. Planning for the exploration technology is addressed, including: photovoltaic, chemical, and thermal energy conversion; power management; thermal management; space nuclear power; high-capacity power; power and thermal management for the surface, earth-orbiting platform, and spacecraft; laser power beaming; and mobile surface systems.
Exploration of our solar system over several decades has benefitted greatly from the sensitive chemical analyses offered by spaceflight mass spectrometers. When dealing with an unknown environment, the broadband detection capabilities of mass analyzers have proven extremely valuable in determining the composition and thereby the basic nature of space environments, including the outer reaches of Earth s atmosphere, interplanetary space, the Moon, and the planets and their satellites. Numerous mass analyzer types, including quadrupole, monopole, sector, ion trap, and time-of-flight have been incorporated in flight instruments and delivered robotically to a variety of planetary environments. All such instruments went through a rigorous process of application-specific development, often including significant miniaturization, testing, and qualification for the space environment. Upcoming missions to Mars and opportunities for missions to Venus, Europa, Saturn, Titan, asteroids, and comets provide new challenges for flight mass spectrometers that push to state of the art in fundamental analytical technique. The Sample Analysis at Mars (SAM) investigation on the recently-launch Mars Science Laboratory (MSL) rover mission incorporates a quadrupole analyzer to support direct evolved gas as well as gas chromatograph-based analysis of martian rocks and atmosphere, seeking signs of a past or present habitable environment. A next-generation linear ion trap mass spectrometer, using both electron impact and laser ionization, is being incorporated into the Mars Organic Molecule Analyzer (MOMA) instrument, which will be flown to Mars in 2018. These and other mass spectrometers and mission concepts at various stages of development will be described.
Polyhydroxyalkanoates (PHAs), a promising class of biomaterials, have gained considerable attention to replace petroleum-based plastics owing to their excellent biocompatibility and biodegradability. Homopolymers of PHA suffer from poor tunability in thermal and mechanical properties. Going from homopolymers to copolymers, the design space can be substantially enhanced by combining two or more monomers in different compositions (i.e., relative ratios of the different monomers) and configurations (i.e., relative positions of the different monomers in the polymer backbone) leading to a substantially large chemical space where application-specific optimization for the targeted functionality can be performed. However, this composition and configuration dependence of properties in the vast PHA copolymer chemical space remains largely unexplored. In this contribution, further building on our past work with PHA homopolymers, we systematically explore these chemical trends for glass-transition temperature (Tg) in PHA copolymers and blends. Overall, our molecular dynamics simulations, utilizing a previously validated force field for PHAs, suggest that these trends are largely governed not only by the homopolymer Tg values but also configuration-dependent interchain interactions in the copolymer system. In particular, our results indicate that the configuration-dependent variation in the target property at a fixed composition can be significant in the presence of hydrogen-bond-forming monomers. These qualitative observations are further rationalized by quantitatively analyzing various closely related atomic level descriptors of copolymers and blends such as monomer mobility, number of hydrogen bonds, and pair correlation functions. The findings presented in this work help to develop a deeper atomistic-level understanding of thermomechanical behavior of PHA-based copolymers and can potentially guide the rational design of biopolymers as environmental-friendly functional materials.
Cometary exploration remains of great importance to virtually all of space science. Because comets are presumed to be remnants of the early solar nebula, they are expected to provide fundamental knowledge as to the origin and development of the solar system as well as to be key to understanding of the source of volatiles and even life itself in the inner solar system. Clearly the time for a detailed study of the composition of these apparent messages from the past has come. A comet rendezvous mission, the Cometary Coma Chemical Composition (C4) Mission, is now being studied as a candidate for the new Discovery program. This mission is a highly-focussed and usefully-limited subset of the Cometary Rendezvous Asteroid Flyby (CRAF) Mission. The C4 mission will concentrate on measurements that will produce an understanding of the composition and physical makeup of a cometary nucleus. The core science goals of the C4 mission are 1) to determine the chemical, elemental, and isotopic composition of a cometary nucleus and 2) to characterize the chemical and isotopic nature of its atmosphere. A related goal is to obtain temporal information about the development of the cometary coma as a function of time and orbital position. The four short-period comets -- Tempel 1, Tempel 2, Churyumov-Gerasimenko, and Wirtanen -which all appear to have acceptable dust production rates, were identified as candidate targets. Mission opportunities have been identified beginning as early as 1998. Tempel I with a launch in 1999, however, remains the baseline comet for studies of and planning the C4 mission. The C4 mission incorporates two science instruments and two engineering instruments in the payload to obtain the desired measurements. The science instruments include an advanced version of the Cometary Ice and Dust Experiment (CIDEX), a mini-CIDEX with a sample collection system, an X-ray Fluorescence Spectrometer and a Pyrolysis-Gas Chromatograph, and a simplified version of the Neutral Gas and Ion Mass Spectrometer (NIGMS). Both of these instruments have substantial heritage as they are based on those developed for the CRAF Mission. The engineering instruments include a simplified Comet Dust Environmental Monitor (SCODEM) and a navigational Camera, NAVCAM. While neither of the instruments will be permitted to establish science requirements, it is anticipated that significant science return will be accomplished Radio science will also be included.
The Two-Stage Acoustic Penetration and Impact Detector is a simple device for measuring the impact event time, the projectile velocity, the flight path direction and the momentum. The results of laboratory tests have shown that this detector can be used in a wide range of projectile size and velocity. According to measurement purposes the size of the detection area, the distance between the front foil and the target plate and the number of microphones as well as the evaluation procedure can easily be adjusted. The target plate area can also be replaced by another foil detector, if two penetration stages are preferred. This active detector is suitable for a variety of applications in meteoroid and space debris exploration. It can also be supplied with capture cell properties for chemical analysis of inside-deposits. Therefore, this measurement principal has been taken into consideration as a possible flight experiment for instance for a later Longer Duration Exposure Facility (LDEF) flight or future space station activities.
Final document is attached. With planetary missions and deep space gateway on the horizon, humankind is entering a new era of space exploration. Manned mission durations will be longer than any previous flight, resupply capabilities are limited, and system robustness is more imperative than ever. Traditional space systems, especially in the realm of carbon dioxide removal and water remediation, are large in size, mass, energy consumption, and number of mechanical moving parts prone to failure. Non-traditional space exploration needs non-traditional technology solutions. Organizational psychologist Adam Grant is well-known for his studies on originality and how non-conformists can move the world. In the words of Adam Grant, "to become original, you have to try something new, which means accepting some measure of risk." As chemical engineers, we shouldn't let that measure of risk stop us from considering ingenious technology. As a part of the new generation of engineers at NASA, I believe we need a paradigm shift in space technology for this new era of exploration.
Phase stability, defect formation energies, and carrier concentrations are closely interrelated features of semiconductors. Due to their joint dependence on the multidimensional chemical potential space, it is challenging to quantitatively establish patterns between these quantities in a given semiconductor, especially when the semiconductor is comprised of multiple elements. To enable synchronous visualization and analysis of these complementary material properties and their interdependence, we developed the Visualization Toolkit for Analyzing Defects in Materials (VTAnDeM). This python-based toolkit allows users to interactively explore how defect formation energies and carrier concentrations vary across the composition and chemical potential spaces of multicomponent semiconductors. Here, we illustrate the computational workflow that employs VTAnDeM as a post-processing tool for first-principles calculations and describe the data organization and theory underlying the visualization scheme. Furthermore, we believe that this software will serve as a useful tool for simultaneously visualizing the often complex and non-intuitive chemical potential – defect – carrier concentration phase space of semiconductors.
Since the Voyager 1 (V1) flyby in 1980, Titans exploration from space and the ground has been ongoing for more than a full revolution of Saturn around the Sun (one Titan year or 29.5 Earth years was completed in May 2010). In this study we search for temporal variations affecting Titans atmospheric thermal and chemical structure within that year. We process Cassini CIRS data taken during the Titan flybys from 2006-2013 and compare them to the 1980 V1IRIS spectra (re-analyzed here). We also consider data from Earth-based and -orbiting observatories (such as from the ISO, re-visited). When we compare the CIRS 2010 and the IRIS data we find limited inter-annual variations, below the 25 or35 levels for the lower and middle, or the high latitudes, respectively. A return to the 1980 stratospheric temperatures and abundances is generally achieved from 50degN to 50degS, indicative of the solar radiation being the dominating energy source at 10 AU, as for the Earth, as predicted by GCM and photochemical models. However, some exceptions exist among the most complex hydrocarbons (C4H2 and C3H4), especially in the North. In the Southern latitudes, since 2012, we see a trend for an increase of several trace gases, possibly indicative of a seasonal atmospheric reversal. At the Northern latitudes we found enhanced abundances around the period of the northern spring equinox in mid-2009 (as in Bampasidis et al. 2012), which subsequently decreased (from 2010-2012) returning to values similar to those found in the V1 epoch a Titanian year before.
Through the respiration process, humans consume oxygen (O2) while producing carbon dioxide (CO2) and water (H2O) as byproducts. For long term space exploration, CO2 concentration in the atmosphere must be managed to prevent hypercapnia. Moreover, CO2 can be used as a source of oxygen through chemical reduction serving to minimize the amount of oxygen required at launch. Reduction can be achieved through a number of techniques. The National Aeronautics and Space Administration (NASA) is currently exploring the Sabatier reaction, the Bosch reaction, and co-electrolysis of CO2 and H2O for this process. Proof-of-concept experiments and prototype units for all three processes have proven capable of returning useful commodities for space exploration. While all three techniques have demonstrated the capacity to reduce CO2 in the laboratory, there is interest in understanding how all three techniques would perform at a system-level within a spacecraft. Consequently, there is an impetus to develop predictive models for these processes that can be readily re-scaled and integrated into larger system models. Such analysis tools provide the ability to evaluate each technique on a comparable basis with respect to processing rates. This manuscript describes the current models for the carbon dioxide reduction processes under parallel developmental e orts. Comparison to experimental data is provided were available for veri cation purposes.
Mixed-anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn 4 Si 2 O 7 Cl 2 . We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon-based connectors from a non-oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H 2 evolution and water oxidation. This work then paves the way to a new family of mixed-anion solids