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At least 433 records · Page 24

Report of the Joint Scientific Mission Definition Team for an infrared astronomical satellite

The joint effort is reported of scientists and engineers from the Netherlands, the United Kingdom, and the United States working as a team for the purpose of exploring the possibility of a cooperative venture. The proposed mission builds upon experience gained from the successful Astronomical Netherlands Satellite (ANS). This satellite will be in a polar orbit at an altitude of 900 km. It will carry an 0.6 m diameter telescope cooled with helium to a temperature near 10K. An array of approximately 100 detectors will be used to measure the infrared flux in four wavelength bands centered at 10, 20, 50, and 100 microns. Sources will be located on the sky with positional accuracy of 1/2 arcminute. The instrument should be able to investigate the structure of extended sources with angular scales up to 1.0 deg. The entire sky will be surveyed and the full lifetime of the mission of about one year will be necessary to complete the survey. Special observational programs will also be incorporated into the mission.

Source record↗

Frontiers of Life Sciences: The Human Exploration of the Moon and Mars

The rapid development of the productive processes after World War II extended human settlements into new ecological niches. Advances in Life Sciences played a decisive role supporting the establishment of human presence in areas of the planet where human life could have not existed otherwise. The evolution of life support systems, and the fabrication of new materials and technologies has enabled humans to inhabit Polar Regions, ocean surfaces and depths; and to leave Earth and occupy Low Earth Orbit. By the end of the 20 th Century, stations in the Antarctic and Arctic, off shore oil platforms, submarines, and space stations had become the ultimate demonstration of human ability to engineer habitats at Earth extreme environments and outer space. As we enter the 21st Century, the next development of human settlements will occur through the exploration of the Moon, Mars, and beyond. The major risks of space exploration derive from long exposure of humans and other life systems to radiation, microgravity, isolation and confinement, dependence on artificial life support systems, and unknown effects (e.g., altered magnetic fields, ultrahigh vacuum on bacteria, fungi, etc.). Countermeasures will require a complete characterization of human and other biological systems adaptation processes. To sustain life in transit and on the surface of the Moon and Mars will require a balance of spacecraft, cargo, astronaut crews, and the use of in situ resources. Limitations on the number of crewmembers, payloads, and the barrenness of the terrain require a novel design for the capabilities needed in transit and at exploration outpost sites. The planned destinations have resources that may be accessed to produce materials, food, shelter, power, and to provide an environment compatible with successful occupation of longterm exploration sites. Once more, the advancements of Life Sciences will be essential for the design of interplanetary voyages and planetary surface operations. This presentation delineates the role of Life Sciences and its frontiers, especially Cell Science, in the context of human exploration. Life support systems, food production, and medical equipment encompass many of vital aspects related to the new vision for NASA.

North, Regina M.↗

Commercialization and Human Settlement of the Moon and Cislunar Space – A Look Ahead at the Possibilities over the Next 50 Years

Over 50 years have passed since the movie 2001: A Space Odyssey debuted in April 1968. In the film, Dr. Heywood Floyd flies to a large artificial gravity space station orbiting Earth aboard a commercial space plane. He then embarks on a commuter flight to the Moon arriving there 25hours later. Today, on the 50th anniversary of the Apollo 11 lunar landing, the images portrayed in 2001 still remain well beyond our capabilities. This paper examines key technologies and systems (in-situ resource utilization, fission power, advanced chemical and nuclear propulsion),and orbiting infrastructure elements (providing a propellant depot and cargo transfer function),that could be developed by NASA and the private sector in future decades allowing the operational capabilities presented in 2001 to be achieved, albeit on a more spartan scale. Lunar derived propellants (LDPs) will be essential to reducing the launch mass requirements from Earth and developing a reusable lunar transportation system (LTS) that can allow initial outposts to evolve into settlements supporting a variety of commercial activities like in-situ propellant production. Deposits of icy regolith found within permanently shadowed craters at the lunar pole scan supply the feedstock material to produce liquid oxygen (LO2) and hydrogen (LH2) propellan tneeded by surface-based lunar landing vehicles (LLVs) using chemical rocket engines. Along the Moon's nearside equatorial corridor, iron oxide-rich volcanic glass beads from vast pyroclasticdeposits, together with mare regolith, can provide the materials to produce lunar-derived LO2plus other important solar wind implanted (SWI) volatiles, including H2 and helium-3. Mega watt classfission power systems will be essential for providing continuous "24/7" power to LLVs will provide cargo and passenger "orbit-to-surface" access and willalso be used to transport LDP to Space Transportation Nodes (STNs) located in lunar polar(LPO) and equatorial orbits (LLO). Spaced-based, reusable lunar transfer vehicles (LTVs),operating between STNs in low Earth orbit (LEO), LLO, and LPO, and able to refuel with LDPs,can offer unique mission capabilities including short transit time crewed cargo transports. Even acommuter shuttle service similar to that portrayed in 2001 appears possible, allowing 1-way trip times to and from the Moon as short as 24 hours. The performance of LTVs using both RL10B-2chemical rockets, and a variant of the nuclear thermal rocket (NTR), the LO2-Augmented NTR(LANTR), are examined and compared. The bipropellant LANTR engine utilizes its divergent nozzle section as an afterburner into which oxygen is injected and supersonically combusted with reactor-heated hydrogen emerging from the engine's sonic throat. If only 1% of the LDP obtained from icy regolith, volcanic glass, and SWI volatile deposits were available for use in lunar orbit,such a supply could support routine commuter flights to the Moon for many thousands of years!This paper provides a look ahead at what might be possible in the not too distant future,quantifies the operational characteristics of key in-space and surface technologies and systems,and provides conceptual designs for the various architectural elements discussed.

Borowski, Stanley K.↗

Low-cost production method for fluorescent particles for liquid flow velocimetry applications

Abstract In this Technical Note, we present a simple and low-cost production method for fluorescent particles perfectly suitable for velocimetry applications. We leverage the unique ability of Nile Red (NR) fluorophores to adsorb on the polymer surface and/or embed itself in between polymeric chains. The laboratory procedure to dye polyamide particles with NR and monetary advantages over commercially available fluorescent particles is outlined. Subsequently, the fluorescence behavior of the dyed particles is tested under a laser illumination source in polar and non-polar liquids. The distinct advantage of the emission spectrum of NR-dyed particles is demonstrated with sample test results.

42 ENGINEERING↗

Ferroelectric Switching in Hybrid Molecular-Beam-Epitaxy-Grown BaTiO 3 Films

Molecular beam epitaxy (MBE) is a promising synthesis technique for both heterostructure growth and epitaxial integration of ferroelectric BaTiO 3 . However, direct measurement of the remnant polarization (P r ) has not been previously reported in MBE-grown BaTiO 3 films. We report the in situ growth of an all-epitaxial SrRuO 3 /BaTiO 3 /SrRuO 3 heterostructure on Nb-doped SrTiO 3 (001) substrates by hybrid MBE using metal–organic precursors. This capacitor structure consisting of 16 nm SrRuO 3 /40 nm BaTiO 3 /16 nm SrRuO 3 shows hysteretic polarization–electric field (P–E) curves with P r ∼ 15 μC cm –2 at frequencies ranging from 500 Hz to 20 kHz, after isolating the intrinsic ferroelectric response from non-ferroelectric contributions using the Positive-Up-Negative-Down (PUND) method. We hypothesize that the asymmetry in switching behavior and current leakage has origins in structural defects. Furthermore, this work opens the door to defect-engineered ferroelectric BaTiO 3 -based heterostructures grown by hybrid MBE for future electronic, photonic and spintronic applications.

SrRuO3 electrode↗

Study of optical techniques for the Ames unitary wind tunnels. Part 3: Angle of attack

A review of optical sensors that are capable of accurate angle of attack measurements in wind tunnels was conducted. These include sensors being used or being developed at NASA Ames and Langley Research Centers, Boeing Airplane Company, McDonald Aircraft Company, Arnold Engineering Development Center, National Aerospace Laboratory of the Netherlands, National Research Council of Canada, and the Royal Aircraft Establishment of England. Some commercial sensors that may be applicable to accurate angle measurements were also reviewed. It was found that the optical sensor systems were based on interferometers, polarized light detector, linear or area photodiode cameras, position sensing photodetectors, and laser scanners. Several of the optical sensors can meet the requirements of the Ames Unitary Plan Wind Tunnel. Two of these, the Boeing interferometer and the Complere lateral effect photodiode sensors are being developed for the Ames Unitary Plan Wind Tunnel.

Lee, George↗

The Chandra X-Ray Observatory Radiation Environmental Model Update

CRMFLX (Chandra Radiation Model of ion FLUX) is a radiation environment risk mitigation tool for use as a decision aid in planning the operation times for Chandra's Advanced CCD Imaging Spectrometer (ACIS) detector. The accurate prediction of the proton flux environment with energies of 100 - 200 keV is needed in order to protect the ACIS detector against proton degradation. Unfortunately, protons of this energy are abundant in the region of space where Chandra must operate. In addition, on-board particle detectors do not measure proton flux levels of the required energy range. CRMFLX is an engineering environment model developed to predict the proton flux in the solar wind, magnetosheath, and magnetosphere phenomenological regions of geospace. This paper describes the upgrades to the ion flux databases for the magnetosphere, magnetosheath, and solar wind regions. These data files were created by using Geotail and Polar spacecraft flux measurements only when the Advanced Composition Explorer (ACE) spacecraft's 0.14 MeV particle flux was below a threshold value. This new database allows for CRMFLX output to be correlated with both the geomagnetic activity level, as represented by the Kp index, as well as with solar proton events. Also, reported in this paper are results of analysis leading to a change in Chandra operations that successfully mitigates the false trigger rate for autonomous radiation events caused by relativistic electron flux contamination of proton channels.

Blackwell, William C.↗

Current NASA In-Situ Resource Utilization (ISRU) Strategic Vision

Perform development to TRL 5/6 through ground demonstration in relevant environment. Perform component/subscale subsystem flight demonstrations on small/mid-size landers. Assess and characterize water in volatiles in lunar polar shadowed regions and craters. Reduce risk of ISRU for mission critical consumables through Integrated End-to-End Flight Demonstrations (pilot scale). Establish initial Human Mission Scale production capability to promote sustainable operations and as anchor for commercial involvement. Identify and characterize polar region environment and resources/volatiles for Science and future Exploration/Commercial applications. Provide ground-truth physical, mineral, and water/volatile resource characteristic information at multiple locations to provide geological context for science-focused theories of volatile placement and initial mining assessments.Test technologies and processes to reduce risk of future extraction/mining systems. Quantify concentration and lateral/vertical distribution of resources/volatiles. Utilize ISRU capabilities to Extend and Enhance Human Lunar Exploration Missions. Provide oxygen (and fuel) to enable reusable human lunar lander (10+ MT/yr O2)Process carbon-based crew waste/trash into gases and propellants; can reduce logistics while minimizing public perception issues (alternative is conversion to radiation shielding). Scavenge unused propellants and hardware from spent landers. Metal extraction from regolith as feedstock for in situ and in space manufacturing demonstrations. Civil engineering and construction aimed at future outpost/infrastructure build-up. Develop and Demonstrate ISRU for Human Mars Missions. ISRU for propellant production (10-15 MT/yr); Liquefy, store, transfer, and refuel ascent vehicle. Use Moon for operational experience and mission validation for Mars: Pre-deployment & remote activation and operation without crew. Storing and transferring mission consumables Landing crew with empty tanks with ISRU propellants already made and waiting. Support/Promote Commercialization of Space. Large scale polar ice mining (100+ MT/yr water)O2/H2 propulsion for landers/cis-lunar transportation with surface and in space depots. In situ construction and energy expansion at mining and human outpost site(s). ISRU Ground Development. Develop and advance ISRU technologies to enable acquisition of resources and processing into mission consumables. Utilize Multi-center collaboration with a portfolio that includes internal NASA work, external contracts, and collaborative agreements/partnerships. Where appropriate, develop lunar ISRU components and subsystems with a Mars-forward application. Engage industry through public-private partnerships to lay the foundation for long-term lunar and space economic development. Spin-in/spin-out technologies for terrestrial applications and industry (mining, oil & gas, alternative energy, construction). Flight Demonstration Path to Operational ISRU. Utilize small demonstrations with near off-the-shelf hardware to obtain critical information quickly on lunar resources and operations. Demonstrate critical technologies and processes that interact with lunar materials and environments. Perform 'pilot plant' demonstrations at architecture relevant scales and durations to reduce the risk for ISRU-provided products for critical human mission applications.

In-situ Resource Utilization↗

Moiré trions in MoSe 2 /WSe 2 heterobilayers

Transition metal dichalcogenide moiré bilayers with spatially periodic potentials have emerged as a highly tunable platform for studying both electronic and excitonic phenomena. The power of these systems lies in the combination of strong Coulomb interactions with the capability of controlling the charge number in a moiré potential trap. Electronically, exotic charge orders at both integer and fractional fillings have been discovered. However, the impact of charging effects on excitons trapped in moiré potentials is poorly understood. Here, we report the observation of moiré trions and their doping-dependent photoluminescence polarization in H-stacked MoSe 2 /WSe 2 heterobilayers. We find that as moiré traps are filled with either electrons or holes, new sets of interlayer exciton photoluminescence peaks with narrow linewidths emerge about 7 meV below the energy of the neutral moiré excitons. Circularly polarized photoluminescence reveals switching from co-circular to cross-circular polarizations as moiré excitons go from being negatively charged and neutral to positively charged. Furthermore, this switching results from the competition between valley-flip and spin-flip energy relaxation pathways of photo-excited electrons during interlayer trion formation. Our results offer a starting point for engineering both bosonic and fermionic many-body effects based on moiré excitons.

36 MATERIALS SCIENCE↗

The 2-8 GHz solar dynamic spectra and polarization measurement feasibility study

The preliminary system design of a Solar Microwave Spectrograph (SMS) is presented. This design resulted from a study to determine the feasibility of measuring solar polarization and dynamic spectra over the range of two to eight GHz, using broadband radio frequency instrumentation and rapid recording equipment in conjunction with radio telescopes. The scientific value of the proposed SMS instrument is discussed, with remarks concerning data reduction and analysis and a presentation of the engineering plan to implement the SMS system.

Haddock, F. T.↗

Nano-Engineered Interfaces in Dual-Layer Electrodes for Protonic Ceramic Cells with Enhanced Stability and Kinetics

Enhancing interfacial stability and charge transfer in protonic ceramic cells (PCCs) remains a critical challenge, as structural degradation and interfacial resistance often compromise durability and efficiency. Here, we report a nanoengineered dual-layer oxygen electrode architecture designed to address these limitations by introducing a fine-grained nanoparticle interfacial contact layer beneath a porous catalytic backbone. The nanoscale powders, through enhanced sintering activity, densify into a robust interfacial layer that promotes strong chemical bonding, uniform adhesion, and continuous ionic/electronic pathways with the BCZYYb electrolyte. This hierarchical architecture mitigates delamination, redistributes mechanical stress, and establishes efficient charge and mass transport channels without relying on corrosive surface treatments. Electrochemical evaluation demonstrates that the dual-layer design markedly reduces interfacial polarization resistance and accelerates electrode kinetics. Compared to the single-layer counterpart, the architecture achieves a peel strength of 44.53 N/cm 2 , a 40% improvement in peak power density (0.96 W cm –2 at 600 °C), and a 130% enhancement in electrolysis current density (4.78 A cm –2 at 1.57 V). Faradaic efficiency remains as high as 88% under high steam concentrations, underscoring minimal charge loss during practical operation. Notably, the electrode retains stability across 450–600 °C and under transient voltage cycling, with impedance spectra confirming suppressed interfacial resistance growth over prolonged use. These results highlight nanoscale interface engineering as a powerful route to enhance both mechanical robustness and electrochemical kinetics in PCCs. The demonstrated scalability and durability of this architecture provide a versatile platform for advancing solid-state electrochemical systems, including reversible fuel cells and high-efficiency hydrogen production technologies.

Faradaic efficiency↗

Accounting for Sustainability and Performance: Contrasting Effects of PET-Derived Modifiers on Asphalt Durability

The valorization of waste plastics in roadway infrastructure requires careful balance between sustainability and performance, as ineffective modifiers may incur both environmental and financial costs. This study shows that two modifiers derived from the same waste plastic source (PET)-DOTP (N1,N4-(dioctyl)terephthalamide) and HETP (N1,N4-Bis(2-hydroxyethyl)terephthalamide)-exhibit opposite effects on asphalt properties, despite having nearly the same carbon footprint. DOTP improves elastic recovery in multiple creep recovery tests (MCRT), while HETP increases strain accumulation and reduces elasticity. Density functional theory (DFT) shows that DOTP's molecular structure can disperse well in bitumen mixtures by binding to both polar and non-polar components. In contrast, HETP binds only to the binder's polar sites, lacking adequate dispersion. This increases the risk of aggregation of polar compounds in the bitumen mixture, resulting in a more deformation-prone binder. A techno-economic analysis highlights trade-offs between sustainability and performance in industrial-scale synthesis. This study advocates for applying first-principles thinking in material design, coupled with experimental validation, to engineer plastic waste-derived additives that achieve both performance and sustainability goals.

36 MATERIALS SCIENCE↗

Highly Tunable Valley Polarization of Potential-Trapped Moiré Excitons in WSe 2 /WS 2 Heterojunctions

Moiré superlattices created by stacking atomic layers of transition metal dichalcogenide semiconductors have emerged as a class of fascinating artificial photonic and electronic materials. An appealing attribute of these structures is the inheritance of the valley degree of freedom from the constituent monolayers. Recent studies show evidence that the valley polarization of the moiré excitons is highly tunable. In heterojunctions of WSe 2 /WS 2 , marked improvement in valley polarization is observed by increasing optical excitation power, a behavior that is quite distinct from the monolayers, and lacks a clear understanding so far. Here, in this Letter, we show that this highly tunable valley property arises from filling of the moiré superlattice, which provides an intriguing mechanism for engineering these quantum opto-valleytronic platforms. Our data further demonstrate that the long-range electron-hole exchange interaction, despite being significantly weakened in the junctions, is the dominant source of moiré exciton intervalley scattering at low population. Using magnetic field tuning, we quantitatively determine the exchange interaction strength to be 0.03 and 0.24 meV for 0° and 60° twisted samples, respectively, in our experiments, about 1 order of magnitude weaker than that in the monolayers.

74 ATOMIC AND MOLECULAR PHYSICS↗

Atomic-Scale Imaging of Polarization Switching in an (Anti-)Ferroelectric Memory Material: Zirconia (ZrO2)

Direct, atomic-scale visualization of polarization switching in a functional, polycrystalline, binary oxide via in-situ high-resolution transmission electron microscopy (HRTEM) biasing is reported for the first time. Antiferroelectric (AFE) ZrO2 was used as the model system, which is important for commercial DRAMs and as emerging NVMs (through work-function engineering). We observed (1) clear shifting and coalescing of domains within a single grain, and (2) dramatic changes of the atomic arrangements and crystalline phases—both at voltages above the critical voltage measured for AFE switching. Similar synergistic in-situ structural-electrical characterization can pave the way to understand and engineer microscopic mechanisms for retention, fatigue, variability, sub-coercive switching and analog states in ferroelectric and AFE-based memory devices.

Lombardo, Sarah↗

Calibration of the Geosar Dual Frequency Interferometric SAR

GeoSAR is an airborne, interferometric Synthetic Aperture Radar (INSAR) system for terrain mapping, currently under development by a consortium including NASA's Jet Propulsion Laboratory (JPL), Calgis, Inc., and the California Department of Conservation (CalDOC) with funding provided by the Topographic Engineering Center (TEC) of the U.S. Army Corps of Engineers and the Defense Advanced Research Projects Agency (DARPA). The radar simultaneously maps swaths on both sides of the aircraft at two frequencies, X-Band and P-Band. For the P-Band system, data is collected for two across track interferometric baselines and at the crossed polarization. The aircraft position and attitude are measured using two Honeywell Embedded GPS Inertial Navigation Units (EGI) and an Ashtech Z12 GPS receiver. The mechanical orientation and position of the antennas are actively measured using a Laser Baseline Metrology System (LBMS). In the GeoSAR motion measurement software, these data are optimally combined with data from a nearby ground station using Ashtech PNAV software to produce the position, orientation, and baseline information are used to process the dual frequency radar data. Proper calibration of the GeoSAR system is essential to obtaining digital elevation models (DEMS) with the required sub-meter level planimetric and vertical accuracies. Calibration begins with the determination of the yaw and pitch biases for the two EGI units. Common range delays are determined for each mode, along with differential time and phase delays between channels. Because the antennas are measured by the LBMS, baseline calibration consists primarily of measuring a constant offset between mechanical center and the electrical phase center of the antennas. A phase screen, an offset to the interferometric phase difference which is a function of absolute phase, is applied to the interferometric data to compensate for multipath and leakage. Calibration parameters are calculated for each of the ten processing modes, each of the operational bandwidths (80 and 160 MHZ), and each aircraft altitude. In this talk we will discuss the layout calibration sites, the synthesis of data from multiple flights to improve the calibration, methods for determining time and phase delays, and techniques for determining radiometric and polarimetric quantities. We will describe how calibration quantities are incorporated into the processor and pre-processor. We will demonstrate our techniques applied to GeoSar data and assess the stability and accuracy of the calibration. This will be compared to the modeled performance determined from calibrating the output of a point target simulator. The details of baseline determination and phase screen calculation are covered in related talks.

Chapine, Elaine↗

Advanced Water Recovery Technologies for Long Duration Space Exploration Missions

Extended-duration space travel and habitation require recovering water from wastewater generated in spacecrafts and extraterrestrial outposts since the largest consumable for human life support is water. Many wastewater treatment technologies used for terrestrial applications are adoptable to extraterrestrial situations but challenges remain as constraints of space flights and habitation impose severe limitations of these technologies. Membrane-based technologies, particularly membrane filtration, have been widely studied by NASA and NASA-funded research groups for possible applications in space wastewater treatment. The advantages of membrane filtration are apparent: it is energy-efficient and compact, needs little consumable other than replacement membranes and cleaning agents, and doesn't involve multiphase flow, which is big plus for operations under microgravity environment. However, membrane lifespan and performance are affected by the phenomena of concentration polarization and membrane fouling. This article attempts to survey current status of membrane technologies related to wastewater treatment and desalination in the context of space exploration and quantify them in terms of readiness level for space exploration. This paper also makes specific recommendations and predictions on how scientist and engineers involving designing, testing, and developing space-certified membrane-based advanced water recovery technologies can improve the likelihood of successful development of an effective regenerative human life support system for long-duration space missions.

Liu, Scan X.↗

Up‐And‐Coming Advances in Optical and Microwave Nonreciprocity: From Classical to Quantum Realm

Reciprocity is a fundamental physical principle that roots in the time‐reversal symmetry of physical laws. It allows making predictions on any arbitrary complex system's response and operation and hence simplifies the analysis. However, there are many practical situations in which it is advantageous to break reciprocity, e.g., isolators preventing wave scattering back to lasers and generators, full‐duplex systems for multiplexing transmission and receiving in the same channel, nonreciprocal cavity excitation, and protection of fragile states of superconductor quantum computers from thermal noise. The most widespread approach to time‐reversal symmetry breaking and nonreciprocity based on magnetic field biasing suffers from bulkiness, cost ineffectiveness, and loss, motivating researchers and engineers to search for more practical approaches. Herein, the up‐and‐coming advances in optical nonreciprocity, including new materials (Weyl semimetals, topological insulators, metasurfaces), active structures, time‐modulation, parity‐time (PT)‐symmetry breaking, nonlinearity combined with a structural asymmetry, quantum nonlinearity, unidirectional gain and loss, chiral quantum states and valley polarization are overviewed. A general description of nonreciprocal systems is provided and the pros and cons of the mentioned approaches to nonreciprocity are discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗