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All sourcesNASA NTRSDOE OSTI
NASA NTRS2023

The Mars Atmosphere Water Ice Aerosol Climatology by MRO/CRISM: 5 Mars Years of Observations

We use near-infrared spectra returned from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO) to provide retrievals of the column-integrated optical depth of water ice aerosols for more than 5 Martian years between Mars Year (MY) 28 at Ls = 112° (27 September 2006) and MY 33 at Ls = 213° (30 August 2016). We have developed a radiative transfer model for this purpose that retrieves aerosol opacity from the water ice aerosol feature near 3.3 μm using CRISM hyperspectral observations for the first time. The resulting retrievals well depict the main features in the water ice aerosol climatology with repeatable patterns every Martian year. The aphelion cloud belt (ACB) is observed between 10°S and 30°N, with peak optical depth around Ls = 90°. Apart from the global dust storm during MY 28, modest interannual variability in the water ice aerosol optical depth is observed in the ACB. The north polar hood is observed at latitudes poleward of 45°N throughout northern spring and summer seasons and reappears in northern winter. The south polar hood is observed in early to mid-southern autumn, reaching latitudes around 60°S, and re-emerging during southern winter between 45°S and 60°S. A lack of water ice aerosols is repeatedly seen in the southern hemisphere throughout southern spring and summer. High optical depth in the ACB is observed over the volcanoes of Olympus Mons, Elysium, and the Tharsis bulge, as well as over Hellas Basin.

Mars↗
NASA NTRSDate not supplied

Wire-break Ignition Testing of Materials for Spacesuit Fire Hazard Control

The input design constraints applied to the extravehicular activity (EVA) spacesuit pose a significant challenge for mitigation of fire hazards. To minimize fatigue and increase comfort of the crewmember operating the suit, the suit pressure is lowered below sea level conditions with typical EVA suit designs operating with 4.3 psia (29.7 kPa). With the lowered operating pressures and the use of closed-loop life support, the suit requires elevated concentrations of oxygen, typically >95%. At these oxygen concentrations, nearly the entirety of the suit internal materials are flammable. This leaves one remaining possible control leg of the fire triangle: ignition sources. Since the Gemini and Apollo programs, this has been a risk that has undergone constant reassessment, with a focus on improved mitigation. After the Apollo I fire, an arc ignition method was developed and used to quantify ignition thresholds for in-suit materials resulting in a current limit for powered in-suit devices applied to all subsequent suit designs. After the discovery of a frayed spacesuit biomed cable on STS-113 during the Shuttle Program, the previous arcing method was repeated with additional methods developed to extend the testing further. One of those methods was wire-break ignition testing, in which the current in a single strand of wire was progressively increased, preheating the material in proximity with a resultant break and the application of a reasonably repeatable arc to ignite the material, all while exposed in the selected environment. This method was used to test a suite of spacesuit materials providing relative performance with respect to ignition with this configuration for application of energy. This paper discusses extension of the current data set to address recent material additions, lowering of energy test levels for quantification of materials too low to measure in previous testing, as well as future plans to improve this method.

Colin Campbell↗
NASA NTRS2024

Thermal Cycling of Stationary Superconducting Rotor Coils for the High Efficiency Megawatt Motor

The self-cooled, superconducting rotor included in the design of the High Efficiency Megawatt Motor (HEMM) can produce magnetic field strengths far higher than those produced using conventional approaches. However, the superconductivity properties of high-temperature superconducting coils can degrade as the coil is repeatedly thermally cycled, significantly impacting the HEMM’s performance. To explore ways to reduce this risk, NASA researchers fabricated and tested several coils of increasing complexity. The results of the testing campaign indicate that NASA can fabricate and test full-scale superconducting coils for the rotor of the HEMM that can reliably survive repeated thermal cycling with no or acceptably slow degradation.

Electrified Aircraft Propulsion↗
NASA NTRSDate not supplied

In-Orbit Selection of Cryocooler Drive Frequencies for XRISM/Resolve

The XRISM/Resolve instrument cooling system uses adiabatic demagnetization refrigerators (ADRs) to cool the detectors to 50 mK and Joule-Thomson and Stirling cryocoolers to reduce heat load on the He tank supporting the ADRs. Resolve was designed with tunable cryocooler drive frequencies so that interference could be avoided. The cryocooler generated micro-vibration changes with drive frequency and that micro-vibration causes interference and degrades instrument performance. Poor drive frequency choices have been shown to dramatically impact ADR cooling power, temperature stability, detector noise, and degrading spectroscopic performance. However, some choices are free of these features, allowing the instrument to satisfy its performance requirements with significant margin. Thus, the choice of drive frequencies is critical to achieving peak instrument performance. The drive frequencies of the Joule-Thomson cooler, near 52 Hz, and the Stirling coolers, near 15 Hz, were adjusted in three scan sequences while measuring interference to narrow candidate frequency options. Choices were based on stability of the 50 mK control thermometer, changes in the ADR demagnetization rate, and changes in detector noise. These scans were performed routinely during ground testing. Surprisingly though, the results were not repeatable after the Dewar was warmed and re-cooled but were repeatable when remeasured during the same test campaign. Since the good/bad drive frequencies change during Dewar warmup/cooldown, and possibly after vibration events, the drive frequencies could not be finalized before launch. This paper describes the cryocooler frequency scan measurements and compares the results during instrument commissioning to those performed during ground tests.

XRISM↗
NASA NTRSDate not supplied

In-Orbit Selection of Cryocooler Drive Frequencies for XRISM/Resolve

The XRISM/Resolve instrument cooling system uses adiabatic demagnetization refrigerators (ADRs) to cool the detectors to 50 mK and two types of cryocoolers to reduce heat load on the He tank, Joule-Thomson and Stirling cryocoolers. Resolve was designed with tunable cryocooler frequencies so that any mechanical interference and its effect on performance could be minimized. Measurements at different cryocooler drive frequencies were used to quantify the interference and narrow the acceptable range of frequency options. For Resolve the choice of cryocooler drive frequencies dramatically influences the instrument performance. Poor choices have been shown to degrade ADR cooling power and degrade the spectroscopic performance of the instrument. However, good choices have been shown to be free of undesirable features, allowing the instrument to satisfy its performance requirements with significant margin. Thus, the choice of drive frequencies is a critical factor for overall instrument performance. The drive frequencies of the Joule-Thomson cooler operating near 52 Hz, and the Stirling coolers operating near 15 Hz were adjusted in three distinct scan sequences to efficiently narrow the candidate frequency options. The frequency choices were based on stability of the 50 mK control thermometer, changes in the ADR demagnetization rate, and changes in detector noise. Scans across the drive frequency range of each cryocooler were performed multiple times during ground testing. Surprisingly, the results were not repeatable across test campaigns and did not conform to any discernable trend, but they were repeatable when remeasured within a single cool-down cycle. The conclusion was that the good/bad drive frequencies changed during Dewar warmup/cooldown, and possibly after mechanical vibration tests. Therefore, the settings could not be finalized before launch, and scans during instrument commissioning were necessary. This paper describes the cryocooler frequency scan measurements and compares the results during instrument commissioning to those performed during ground tests.

XRISM↗
NASA NTRS2025

Measuring Unique Contextual Factors: Group Living Skills

BACKGROUND The Human Factors and Behavioral Performance Exploration Measures (HFBP-EM) suite is a set of standardized measures used to assess behavioral health and performance risks related to future exploration-class space missions. During the HFBP-EM suite development, the importance of assessing unique contextual factors to understand the drivers of team dynamics was identified. Group living skills are a unique workplace skill which applies to those coworkers who live and work together. As mission lengths become longer, the line between work and non-work life may blur. Extreme living conditions such as spaceflight can result in increased stress over time, negatively impact mood and well-being, decrease team cohesion and increase conflict, deteriorate task performance, and potentially reduce mission success [1]. With no breaks in their isolated and confined environment possible, living with a messy, inconsiderate crewmember can add to the stress. Alternatively, crews with good group living skills may support one another, mitigating the negative effects of the extreme environment. There was no direct measure of group living skills. This work sought to fill this measurement gap and collect data related to group living in isolated, confined, extreme (ICE) environments. METHODS Group living skills as an astronaut competency area were developed with the input of experts familiar with ICE environments. Distinct aspects of this competency were reviewed and discussed by a NASA-invited group of spaceflight experts in 2015 to identify individual and team behavioral health and performance measures for operational environments. This work resulted in a 5-item measure focused on group living experiences with each crewmember (or the crew as a whole). A 6th item asks whether an individual would go on another mission with a particular crewmember or crew as a measure of future-oriented group living, or team viability. The measure was deployed in 24 teams living and working together in isolated and confined environments (e.g., International Space Station, space mission simulation analogs). RESULTS & DISCUSSION In this presentation, we will summarize results which indicate the Group Living Skills (GLS) Survey is a reliable, valid, and operationally feasible measure. Reliability was evaluated in several ways. Two-way multilevel mixed models revealed strong repeated measures reliability (ICC2 = .902, Omega between = .954). Reliability of change within teams was strong (Rc = .81). Factor analysis showed a consistent two-factor structure when individuals rated either the whole crew, all individuals, just peers, or a focal roommate. The latter used a sociometric approach to rating the GLS of the roommates. The two factors were tidiness and being considerate of others. We assessed the criterion-related validity of GLS, by examining GLS operationalized as the team-level aggregated GLS Survey scores as a predictor of team viability, team cohesion, and team performance. We used generalized mixed models to account for the repeated measures and longitudinal data. The marginal R2 change was used to determine the extent to which GLS were related to the team outcomes while controlling for mission day and campaign. Results suggested GLS was strongly related to team viability (marginal R2 change = .40), team cohesion (marginal R2 change = 0.28), social cohesion (marginal R2 change = 0.25), and moderately related to task cohesion (marginal R2 change = 0.18). GLS scores had a small relationship with team performance (marginal R2 change = .08). Results support GLS as a measure that can be used to capture group living skills of crews who live and work together in ICE. Because the items were written to be broadly applicable, less extreme environments with teams living and working together for some length of time also benefit from this measure (e.g., college roommates, camps). See Landon et al. (2024) for full results [2]. SUMMARY We report reliability and validity evidence for a new measure that assesses the Group Living Skills for teams that live and work in operational environments such as spaceflight.

J C W Miller↗
NASA NTRS2002

Analysis of various two synodic period Earth-Mars cycler trajectories

Trajectories that regularly encounter Earth and Mars but use small or no propulsive maneuvers are known as cycler trajectories, or cyclers. For cyclers that repeat after two Earth-Mars synodic periods, several variations are possible. A detailed investigation is presented of a simple two synodic period cycler, along with several promising variations using combinations of one year and half-year phasing orbits. Analysis is included for both the circular co-planar model and with actual Earth and Mars ephemerides.

trajectory cycler repeat orbits↗
NASA NTRS2006

On the design of a science orbit about Europa

A science mission about Europa requires high-inclination low-altitude orbits. However, perturbations of Jupiter on the orbiter result in instability. Previous approaches to maximize the lifetime of the orbiter use the doubly averaged problem. We work with the unaveraged equations and find unstable periodic orbits with long lifetimes. These low-altitude repeat ground track solutions exist at all inclinations, making them suitable for mapping missions. The governing dynamics include Hill's model and a Europa gravity field based on synchronous moon theory. Inclusion of additional gravity terms is trivial to the solution method, and for the case of J3, we find a marginal impact on orbit lifetime. The science orbits are found to last on the order of 1 year when the initial conditions are achieved to 11 significant digits and 4 months when only 3 significant digits are achieved. Finally, we demonstrate that the solutions are robust in a realistic ephemeris model, finding average lifetimes of 3 to 4 months for wide range of initial conditions with peak lifetimes of up to 6 months.

unstable↗
NASA NTRS2011

Onboard Radar Processing Development for Rapid Response Applications

We are developing onboard processor (OBP) technology to streamline data acquisition on-demand and explore the potential of the L-band SAR instrument onboard the proposed DESDynI mission and UAVSAR for rapid response applications. The technology would enable the observation and use of surface change data over rapidly evolving natural hazards, both as an aid to scientific understanding and to provide timely data to agencies responsible for the management and mitigation of natural disasters. We are adapting complex science algorithms for surface water extent to detect flooding, snow/water/ice classification to assist in transportation/ shipping forecasts, and repeat-pass change detection to detect disturbances. We are near completion of the development of a custom FPGA board to meet the specific memory and processing needs of L-band SAR processor algorithms and high speed interfaces to reformat and route raw radar data to/from the FPGA processor board. We have also developed a high fidelity Matlab model of the SAR processor that is modularized and parameterized for ease to prototype various SAR processor algorithms targeted for the FPGA. We will be testing the OBP and rapid response algorithms with UAVSAR data to determine the fidelity of the products.

dual polarized data↗
NASA NTRS2019

Compass Final Report: Europa Tunnelbot

The Compass Final Report: Europa Tunnelbot, is a summary of three Compass concurrent engineering team designs for penetrating the ice of Europa and reaching the ocean, while sampling for biomarkers and communicating back to the surface. These conceptual designs, while providing complete conceptual layouts for these penetrators, or 'Tunnelbots' along with the associated communication 'Repeaters' primarily focused on the power and thermal systems needed for these devices. Trades for these systems will provide advantages and challenges for each option. These results will be used to guide power technology development.

probe↗
NASA NTRS2021

Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin

Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar giant flares (MGFs). Three have been observed from the Milky Way and its satellite galaxies, and they have long been suspected to constitute a third class of extragalactic GRBs. We report the unambiguous identification of a distinct population of four local (<5 Mpc) short GRBs, adding GRB 070222 to previously discussed events. While identified solely based on alignment with nearby star-forming galaxies, their rise time and isotropic energy release are independently inconsistent with the larger short GRB population at >99.9% confidence. These properties, the host galaxies, and non-detection in gravitational waves all point to an extragalactic MGF origin. Despite the small sample, the inferred volumetric rates for events above 4 × 10(exp 44) erg of R(sub MGF) =3.8(sup +4.0)(sub -3.1) ×10(exp 5) Gpc(exp -3) yr(exp -1) make MGFs the dominant gamma-ray transient detected from extragalactic sources. As previously suggested, these rates imply that some magnetars produce multiple MGFs, providing a source of repeating GRBs. The rates and host galaxies favor common CCSN as key progenitors of magnetars.

Gamma-ray bursts↗
NASA NTRSDate not supplied

Comparison of Micromechanics Theories for Modeling Discontinuous Long Fiber Reinforced Composites

Two micromechanics theories, the high fidelity generalized method of cells and Carrera Unified Formulation, are used to model a repeating unit cell of a discrete long fiber composite. The models are used to predict the effective properties of a single fiber with varying fiber-to-fiber end gap lengths, as well as the local stresses in the fiber and matrix. Both models produced similar results and demonstrated that they could capture the complex local load transfer due to the shear lag effect.

discrete long fiber composites↗
NASA NTRS2024

Filament Wound Composite Analysis Using the NASA Multiscale Analysis Tool (NASMAT) and Finite Element Analysis

Fiber reinforced composite materials, owing to their tailorable thermomechanical and functional properties, allow one to produce a structure that is stronger, stiffer, and lighter than its metal counterpart while performing the same function, yielding a more efficient structure. This not only allows for the improvement of current technologies like aircraft structures, but also enables new technologies like gaseous hydrogen storage for mobility applications, which are otherwise impractical when manufactured using traditional metals due to weight and space restrictions or material embrittlement. However, the use of composites imposes greater design and manufacturing challenges on an engineer, since they are heterogenous, having a distinct structure across multiple length scale, behave generally anisotropically at the structural level and require complex manufacturing and processing methods. Capturing this complex behavior requires detailed numerical simulations, including the modeling of microstructural features like undulations, voids, and fiber alignment. In this paper, multiple repeating unit cells (RUCs), representing filament wound composites, are developed (via a script provided in the Appendix) and analyzed. The refinement of these RUCs is varied, and the analyses are performed using both the Abaqus finite element software and the NASA Multiscale Analysis Tool (NASMAT). A study is undertaken to compare the predicted effective elastic properties of the wound RUC to a laminate representation of the wound RUC, which neglects the undulations. Additionally, two different sets of periodic boundary conditions (PBCs) have been examined. One approximates the real boundary conditions using a standard approach and the other represents the PBCs exactly through the use of an offset. Lastly, a comparison of the local elastic stress fields is made among the models and approaches. Since wound structures are often approximated as laminated structures, it is important to understand the degree to which this assumption is valid, namely by first comparing the elastic constants and local elastic fields. This will provide, on the one hand, information concerning the bulk mechanical behavior and, on the other hand, insights concerning local load distributions and likely damage initiation sites.

Composites↗
NASA NTRS1962

NASA TO LAUNCH RELAY EXPERIMENTAL SATELLITE

Objectives of Project Relay are to test intercontinental microwave communications by low-altitude active repeater satellites, measure energy levels of space radiation in the orbital path and determine the extent of radiation damage to solar cells and electronic components. A second Relay satellite will be launched next year. Information obtained from the Relay experiments will contribute, ultimately, to development of a future operational satellite system for world- wide communication.

COMMUNICATIONS SATELLITE↗
NASA NTRS1962

Studies in the Fields of Space Flight and Guidance Theory: Progress Report - No. 2

Compiled in this paper are 11 progress papers from 7 of the agencies working under contract to MSFC in the areas of guidance theory and space flight theory. This is the second paper of the "Progress Reports" and covers the period from December 1, 1961 to June 15, 1962. Extensive references are made to "Progress Report No. 1." This second progress report is referred to as "report" and "Progress Report No. 1" will be referred to as the "first report" in this introduction. Information given in the first report is not repeated herein. The reports of the various contractors will be referred to by index number as papers. There are two parallel series of publications covering the over-all activities at MSFC in the areas of guidance theory and space flight theory. One is the series of progress reports of which this paper is the second in the series. The other is the series of "Status Reports on Theory of Space Flight and Adaptive Guidance." These series along with a few other special reports, give a complete picture of the immediate objectives, accomplishments, and final goals of Aeroballistics Division and associated contr

FLIGHT OPTIMIZATION↗