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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS2025

Time Course of Effects of Carbon Dioxide Exposure on Physical and Cognitive Performance in a Simulated Surface Extravehicular Activity Contingency Scenario

INTRODUCTION Carbon dioxide (CO 2 ) is a metabolic byproduct produced by humans that must be scrubbed from the atmosphere by environmental control and life support systems in space vehicles and spacesuits to prevent buildup. Current nominal CO 2 limits are set by NASA Standard 3001, however, limits during contingency situations are not specified. The purpose of this study was to characterize and quantify the physiological, cognitive, and self-assessed symptom and performance metrics as a function of inspired CO 2 (P I CO 2 ) during a simulated 1-hour contingency lunar EVA scenario in virtual reality (VR). METHODS Fifteen healthy subjects completed 7 simulated EVA scenarios walking on a passive treadmill for one hour breathing dry, ambient air mixed with added CO 2 in a blind, counterbalanced manner (P I CO 2 : 0, 5, 10, 15, 20, 25, 30 mmHg) simulating a 2.0 km contingency EVA walkback to a habitat on the lunar surface in the event of a CO 2 scrubber malfunction. Subjects were immersed in a Lunar VR environment and asked to maintain their walking speed between 2.1 km/h and an upper limit individually calibrated to a fixed metabolic workload of 1.3 L/min of O 2 consumption, and performed periodic cognitive tasks and continuous cardiopulmonary measurements. Self-assessments of symptoms and task performance were measured via verbal Likert-scale survey at the onset of the walkback and at 10-minute intervals thereafter. RESULTS The time course of cardiopulmonary, cognitive, and self-reported responses at each level of P I CO 2 will be presented. All 15 subjects were able to complete the 1-hr walk back task at all CO 2 levels. Physiological responses were rapid, typically within 1 to 5 minutes. No effects of time were detected for cognitive measures. Symptomatic ratings of headache, shortness of breath, and fatigue demonstrated a time-course development, reaching asymptote after 40 minutes of CO 2 exposure. DISCUSSION These findings will inform the posture of risk associated with CO 2 exposure on human health and performance during microgravity and planetary surface operations, This will help inform decisions related to space suit and environmental life support hardware requirements and EVA operational limits for contingency extravehicular activity (EVA) scenarios.

carbon dioxide↗
NASA NTRS2025

Mars Ground Level Enhancements in the Context of the Solar Energetic Particle Clock

In this work we discuss the growing ensemble of solar particle events registered on the Martian surface, including their temporal appearance and solar sources. Solar energetic particle events from the surface of Mars have been observed starting soon after the August 2012 landing of the Radiation Assessment Detector onboard Curiosity. The Martian atmosphere prevents protons and heavy ions of up to 180 MeV/n kinetic energy from directly reaching the Martian surface. This cut-off is high enough to limit the number of solar energetic particle events measured on the surface to only 15 in ~12 ½ years. Yet we find in this analysis that Mars ground level enhancements follow the distinct SEP clock pattern as proton events observed at lower energies as reported in Posner, Richardson and Strauss (2024). Proton acceleration occurs predominantly near the solar surface, while transport to Mars incurs a delay in onset, and, as we show here, peak, that is a function of the longitudinal magnetic connection distance. between the foot point of solar wind magnetic field lines that intersect the Mars environment with the source longitude of the solar magnetic eruption. A distinct clustering of relative solar source locations at or near the Mars foot points at the Sun’s western limb is apparent, indicating lower flux thresholds from such preferred locations. Our findings have implications for astronaut safety at Mars.

Mars Ground Level Enhancements↗
NASA NTRS2025

JWST Reveals Spectral Tracers of Recent Surface Modification on Europa

Europa has been modified by a variety of geologic processes, exposing internally-derived materials that are heavily irradiated by charged particles trapped in Jupiter’s magnetosphere. Prior spectral analysis of H2O ice on Europa relied on low signal-to-noise data at wavelengths >2.5 µm, limiting assessment of a 3.1 µm Fresnel peak that is diagnostic of exposed crystalline ice. We report new measurements of H2O ice spectral features using high signal-to-noise data collected by the NIRSpec spectrograph (1.48 – 5.35 µm) on the James Webb Space Telescope. These data reveal a narrow 3.1 µm crystalline H2O ice Fresnel peak, which is primarily located at southern latitudes in Tara and Powys Regiones. Our analysis indicates that crystalline ice exposed in these low-latitude regiones is likely sustained by ongoing thermal (re)crystallization outpacing charged particle amorphization of the top ∼10 µm of Europa’s regolith over short timescales (<15 days). We also measured H2O ice features centered near 1.5 µm, 1.65 µm, and 2.0 µm, and a broad 3.6 µm H2O continuum peak, which are all stronger at northern latitudes, in contrast to the 3.1 µm Fresnel peak identified at southern latitudes. These results support the hypothesis that H2O ice in Europa’s regolith is vertically stratified, with amorphous ice grains dominating its exposed surface, except in Tara and Powys Regiones. We also find that a previously detected 4.38 µm 13CO2 feature is present almost exclusively at southern latitudes in Tara and Powys Regiones, likely derived from an internal source of carbon-bearing material.

Surface processes (2116)↗
NASA NTRS2025

A Review of Direct Ink Writing of Polymer Derived Ceramics

With the growing demand for materials capable of withstanding extreme temperatures and pressures, ceramic components with exceptional corrosion resistance and reliable mechanical properties have experienced a significant surge in demand. However, traditional ceramic forming methods involve high-temperatures and energy-intensive processes that often struggle to produce complex parts or composites efficiently. Polymer-Derived Ceramics (PDCs) offer a transformative solution by using polymeric precursors that can be converted into a wide variety of silicon-based and non-silicon-based ceramics through heat treatment. The polymeric nature of PDC precursors enables the fabrication of geometrically intricate components using conventional polymer-forming techniques at significantly lower processing temperatures. Furthermore, PDCs are well-suited for additive manufacturing (AM), allowing the production of complex structural and functional components through cost-effective, low-temperature processes. By leveraging the diverse properties of PDC materials – each with unique advantages and limitations – manufacturers can optimise performance for specific applications. This review provides an overview of the types of PDCs developed to date and their broad range of applications. Specifically, it delves into the Direct Ink Writing (DIW) process, exploring its rheological requirements and the critical role of fillers in tailoring the rheological properties of polymeric precursors to meet the specific demands of DIW.

Victoria Bishop↗