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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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NASA NTRS2022

MMS Observations of Storm-Time Magnetopause Boundary Layers in the Vicinity of the Southern Cusp

During a storm-time interval around winter solstice, observations by the Magnetospheric Multi-Scale (MMS) Mission show multiple distinct magnetopause boundary layers (BLs) in the vicinity of the southern cusp. The microphysics of the solar wind-magnetosphere interaction during storm times are not well understood, because the observations are relatively lacking. This event enables the opportunity to probe the storm-time magnetopause, and observations support that MMS was near a reconnection site equatorward of the southern cusp, suggesting active reconnection in close proximity to closed magnetic flux regions in the BL. The Grid Agnostic magnetohydrodynamics (MHD) for Extended Research Applications global MHD simulation shows evidence for transient secondary reconnection sites near the southern cusp, demonstrating mechanisms to form closed field line regions of the BL.

Brandon L. Burkholder↗
NASA NTRS1994

Analysis of solar spectral irradiance measurements from the SBUV/2-series and the SSBUV instruments

The measurements of the solar ultraviolet spectral irradiance by the two Upper Atmosphere Research Satellite (UARS) solar instruments are validated to agree within their 2-Sigma calibration uncertainties of about 7 percent, as well as with measurements from the two solar instruments on the Shuttle Atmospheric Laboratory for Applications and Science (ATLAS) missions. Additionally, the precision of the two UARS data sets is better than the original 2 percent goal, especially at wavelengths greater than 160 nm. This excellent agreement can be credited to accurate pre-flight calibrations, comprehensive in-flight calibrations to track instrument degradation, and a coordinated validation program among the UARS and ATLAS solar instrument teams. The solar irradiance results presented here include those derived from UARS SUSIM, UARS SOLSTICE, ATLAS SUSIM and ATLAS SSBUV measurements on 29 March 1992 during the ATLAS-1 mission and on 15 April 1993 during the ATLAS-2 mission. Two ultraviolet spectra from 119 to 410 nm are derived as the weighted average of the UARS SOLSTICE and SUSIM measurements and are recommended as representative solar spectra for the period of the ATLAS-1 and ATLAS-2 missions. The ATLAS-1 mission occurred during the initial phase of the solar cycle 22 decline when solar activity was moderately high. The ATLAS-2 mission occurred later during the declining phase of the solar cycle 22 when solar activity was more moderate.

Cebula, Richard P.↗
NASA NTRS2003

SORCE and Future Satellite Observations of Solar Irradiance

With solar activity just passing the maximum of cycle 23, SORCE is beginning a 5 year mission to measure total solar irradiance (TSI) with unprecedented accuracy using phase-sensitive detection, and to measure spectral solar irradiance (SSI) with unprecedented spectral coverage, from 1 to 2000 nm. The new Total Irradiance Monitor (TIM) has 4 active cavity radiometers, any one of which can be used as a fixed-temperature reference against any other that is exposed to the Sun via a shutter that cycles at a rate designed to minimize noise at the shutter frequency. The new Spectral Irradiance Monitor (SIM) is a dual Fery prism spectrometer that can employ either prism as a monochromatic source on the other prism, thus monitoring its transmission during the mission lifetime. Either prism can measure SSI from 200 to 2000 nm, employing the same phase-sensitive electrical substitution strategy as TIM. SORCE also carries dual SOLSTICE instruments to cover the spectral range 100-320 nm, similar to the instruments onboard UARS, and also an XUV Photometer System (XPS) similar to that on TIMED. SSI has now been added to TSI as a requirement of EOS and NPOESS, because different spectral components drive different components of the climate system - UV into upper atmosphere and stratospheric ozone, IR into tropospheric water vapor and clouds, and Visible into the oceans and biosphere. Succeeding satellite missions being planned for 2006 and 2011 will continue to monitor these critical solar variables.

Cahalan, Robert F.↗
NASA NTRS2002

SORCE: Solar Radiation and Climate Experiment

Contents include the following: Understanding the Sun's influence on the Earth; How the Sun affect Earth's climate; By how much does the Sun's radiation very; Understanding Solar irradiance; History of Solar irradiance observations; The SORCE mission; How do the SORCE instruments measure solar radiation; Total irradiance monitor (TIM); Spectral irradiance monitor (SIM); Solar stellar irradiance comparison experiment (SOLSTICE); XUV photometer system (XPS).

Cahalan, Robert↗
NASA NTRS2005

Mars Exploration Rover surface mission flight thermal performance

NASA launched two rovers in June and July of 2003 as a part of the Mars Exploration Rover (MER) project. MER-A (Spirit) landed on Mars in Gusev Crater at 15 degrees South latitude and 175 degree East longitude on January 4, 2004 (Squyres, et al., Dec. 2004)). MER-B (Opportunity) landed on Mars in Terra Meridiani at 2 degrees South latitude and 354 degrees East longitude on January 25, 2004 (Squyres, et al., August 2004) Both rovers have well exceeded their design lifetime (90 Sols) by more than a factor of 4. Spirit and Opportunity are still healthy and continue to execute their roving science missions at the time of this writing. This paper discusses rover flight thermal performance during the surface missions of both vehicles, covering roughly the time from the MER-A landing in late Southern Summer (Ls = 328, Sol 1A) through the Southern Winter solstice (Ls = 90, Sol 255A) to nearly Southern Vernal equinox (Ls = 160 , Sol 398A).

thermal design↗
NASA NTRS2004

Solar Activity and its Impact on Earth's Climate

The Sun's activity is now approaching an expected 2006 minimum, following the dramatic maximum of Solar Cycle 23, that included events such as the 2001 "Bastille Day" Coronal Mass Ejection, and the record-setting Oct-Nov 2003 solar flares, with their associated sunspots and variations in Total Solar Irradiance, or TSI. On Nov 4,2003 the largest X-ray flare ever detected (X-28) was observed in detail. We discuss recent satellite measurements of TSI by ACRIM 2 and 3 and Virgo, and new precision observations of TSI and SSI (Solar Spectral Irradiance) from the SORCE mission, that launched on January 25,2003. TSI variations recorded during the June 8,2004 transit of Venus show the unprecedented precision of the SORCE Total Irradiance Monitor (TIM) instrument, the first of its kind to employ phase-sensitive detection. The SORCE spectral instruments, XPS, Solstice, and SIM, record the Sun's changes over a wide range of wavelengths, from 1 to more than 2000 nanometers, for the first time covering the peak of the solar spectrum, including spectral components that provide energy inputs to key components of the climate system - ultraviolet (UV) into the upper atmospheric ozone layer, infrared (IR) into the lower atmosphere and clouds, and Visible into the Oceans and biosphere. Succeeding satellite missions are planned to monitor both TSI and SSI through Cycle 24. We summarize current ideas about decadal and longer solar variability, and associated potential impacts on Earth's climate on time scales from decades to centuries, especially highlighting the role of feedbacks in the climate system.

Cahalan, Robert F.↗
NASA NTRS2013

Thermal Performance of the Mars Science Laboratory Rover During Mars Surface Operations

On November 26, 2011, NASA launched a large (900 kg) rover as part of the Mars Science Laboratory (MSL) mission to Mars. Eight months later, on August 5, 2012, the MSL rover (Curiosity) successfully touched down on the surface of Mars. As of the writing of this paper, the rover had completed over 200 Sols of Mars surface operations in the Gale Crater landing site (4.5 deg S latitude). This paper describes the thermal performance of the MSL Rover during the early part of its two Earth-0.year (670 Sols) prime surface mission. Curiosity landed in Gale Crater during early Spring (Ls=151) in the Southern Hemisphere of Mars. This paper discusses the thermal performance of the rover from landing day (Sol 0) through Summer Solstice (Sol 197) and out to Sol 204. The rover surface thermal design performance was very close to pre-landing predictions. The very successful thermal design allowed a high level of operational power dissipation immediately after landing without overheating and required a minimal amount of survival heating. Early morning operations of cameras and actuators were aided by successful heating activities. MSL rover surface operations thermal experiences are discussed in this paper. Conclusions about the rover surface operations thermal performance are also presented.

thermal design↗
NASA NTRS2026

Hydrofluoroether (HFE) Cleaning Fluid Replacement and Qualification

This NASA Engineering and Safety Center (NESC) Technical Assessment Report addresses the urgent need to identify, test, and qualify replacement cleaning solvents and technologies following 3M’s decision to discontinue production of hydrofluoroether (HFE) products, including Novec HFE-7100, by the end of 2025. HFE-7100 is widely used across NASA for precision cleaning of ground and flight hardware, especially in oxygen system components, and as a heat transfer fluid in high-power-density thermal control systems. The assessment evaluates commercially available replacement solvents, alternative cleaning technologies, and their compatibility with NASA’s operational requirements. Key findings include the identification of viable solvent replacements, their performance in contaminant removal, materials compatibility, and oxygen system safety. The report also explores novel cleaning approaches, including aqueous, supercritical CO₂, cryogenic aerosol, plasma, UV-ozone, magnetically optimized fluids, and induced charge active filtration, highlighting their merits, limitations, and readiness for NASA adoption. The NESC provides recommendations for solvent selection, facility adaptation, and continued technology maturation to ensure mission continuity and regulatory compliance.

Alternative Cleaning Technologies↗
NASA NTRS2013

Thermal Performance of the Mars Science Laboratory Rover During Mars Surface Operations

On November 26, 2011, NASA launched a large (900 kg) rover as part of the Mars Science Laboratory (MSL) mission to Mars. Eight months later, on August 5, 2012, the MSL rover (Curiosity) successfully touched down on the surface of Mars. As of the writing of this paper, the rover had completed over 200 Sols of Mars surface operations in the Gale Crater landing site (4.5 degrees South latitude). This paper describes the thermal performance of the MSL Rover during the early part of its two Earth-0.year (670 Sols) prime surface mission. Curiosity landed in Gale Crater during early Spring (Solar longitude=151) in the Southern Hemisphere of Mars. This paper discusses the thermal performance of the rover from landing day (Sol 0) through Summer Solstice (Sol 197) and out to Sol 204. The rover surface thermal design performance was very close to pre-landing predictions. The very successful thermal design allowed a high level of operational power dissipation immediately after landing without overheating and required a minimal amount of survival heating. Early morning operations of cameras and actuators were aided by successful heating activities. MSL rover surface operations thermal experiences are discussed in this paper. Conclusions about the rover surface operations thermal performance are also presented.

thermal performance↗
NASA NTRS2020

Tidal Effects on the Longitudinal Structures of the Martian Thermosphere and Topside Ionosphere Observed by MAVEN

Longitudinal structures in the Martian thermosphere and topside ionosphere between 150 and 200 km altitudes are studied using in situ electron and neutral measurements from the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Four time intervals are selected for comparison, during which MAVEN sampled similar local time (9.3–10.3 h) and latitude (near 20°S) regions but at different solar longitude positions (two near northern summer solstice, one each at northern vernal and autumnal equinoxes). Persistent and pronounced tidal oscillations characterize the ionosphere and thermosphere, whose longitudinal variations in density are generally in-phase with each other. Our analysis of simultaneous and collocated neutral and electron data provides direct observational evidence for thermosphere-ionosphere coupling through atmospheric tides. We conclude that the ionosphere is subject to modulation by upward-propagating thermal tides, via both tide-induced vertical displacement and photochemical reactions. Atmospheric tides constitute a ubiquitous and significant perturbation source to the ionospheric electron density, up to ∼15% near 200 km.

Xiaohua Fang↗
NASA NTRS2016

Lighting Condition Analysis for Mars Moon Phobos

A manned mission to Phobos may be an important precursor and catalyst for the human exploration of Mars, as it will fully demonstrate the technologies for a successful Mars mission. A comprehensive understanding of Phobos' environment such as lighting condition and gravitational acceleration are essential to the mission success. The lighting condition is one of many critical factors for landing zone selection, vehicle power subsystem design, and surface mobility vehicle path planning. Due to the orbital characteristic of Phobos, the lighting condition will change dramatically from one Martian season to another. This study uses high fidelity computer simulation to investigate the lighting conditions, specifically the solar radiation flux over the surface, on Phobos. Ephemeris data from the Jet Propulsion Laboratory (JPL) DE405 model was used to model the state of the Sun, the Earth, and Mars. An occultation model was developed to simulate Phobos' self-shadowing and its solar eclipses by Mars. The propagated Phobos' state was compared with data from JPL's Horizon system to ensure the accuracy of the result. Results for Phobos lighting condition over one Martian year are presented in this paper, which include length of solar eclipse, average solar radiation intensity, surface exposure time, total maximum solar energy, and total surface solar energy (constrained by incident angle). The results show that Phobos' solar eclipse time changes throughout the Martian year with the maximum eclipse time occurring during the Martian spring and fall equinox and no solar eclipse during the Martian summer and winter solstice. Solar radiation intensity is close to minimum at the summer solstice and close to maximum at the winter solstice. Total surface exposure time is longer near the north pole and around the anti- Mars point. Total maximum solar energy is larger around the anti-Mars point. Total surface solar energy is higher around the anti-Mars point near the equator. The results from this study and others like it will be important in determining landing site selection, vehicle system design and mission operations for the human exploration of Phobos and subsequently Mars.

Li, Zu Qun↗
NASA NTRS1990

SURE (Science User Resource Expert): A science planning and scheduling assistant for a resource based environment

SURE (Science User Resource Expert) is one of three components that compose the SURPASS (Science User Resource Planning and Scheduling System). This system is a planning and scheduling tool which supports distributed planning and scheduling, based on resource allocation and optimization. Currently SURE is being used within the SURPASS by the UARS (Upper Atmospheric Research Satellite) SOLSTICE instrument to build a daily science plan and activity schedule and in a prototyping effort with NASA GSFC to demonstrate distributed planning and scheduling for the SOLSTICE II instrument on the EOS platform. For the SOLSTICE application the SURE utilizes a rule-based system. Development of a rule-based program using Ada CLIPS as opposed to using conventional programming, allows for capture of the science planning and scheduling heuristics in rules and provides flexibility in inserting or removing rules as the scientific objectives and mission constraints change. The SURE system's role as a component in the SURPASS, the purpose of the SURE planning and scheduling tool, the SURE knowledge base, and the software architecture of the SURE component are described.

Thalman, Nancy E.↗
NASA NTRS2002

Overview of the Upper Atmosphere Research Satellite: Observations from 1991 to 2002

The Upper Atmosphere Research Satellite (UARS) was launched in September 1991 by the Space Shuttle Discovery. Seven of the original ten instruments aboard the UARS are functional and six instruments regularly take measurements. The UARS is in a stable observing configuration, in spite of experiencing several anomalies which have impacted the data tape storage and power available. Power sharing and "real-time" operations using the Tracking and Data Relay Satellites have reduced the data collection over the past five years. Although the UARS measurements have not been continuous, the UARS instruments HALOE, SUSIM, SOLSTICE, HRDI, WINDII, and PEM have provided important observations over an entire solar cycle. The UARS HALOE instrument measures ozone and other constituents important in understanding ozone variations. The UARS SUSIM and SOLSTICE instruments observe ultraviolet light between 120 and 420 nm, which influence middle atmospheric constituent fluctuations. The UARS HRDI and WINDII instruments measure winds in the stratosphere, mesosphere, and thermosphere, which move constituents among the various atmospheric regions. The UARS PEM instrument provides observations of input precipitating charged particles, including both electrons and protons. This paper will provide an overview about the UARS mission and its relevant atmospheric measurements.

Jackman, Charles H.↗
NASA NTRS1991

Seasonal variations in the subauroral electron temperature enhancement

A statistical study of the seasonal variations of the subauroral electron temperature enhancement was undertaken using data from the Langmuir probe experiment on the DE 2 satellite throughout most of the mission (1981-1982). In the winter hemisphere the nighttime background electron temperature is the highest and the magnitude of the peak Te responds most weakly to the geomagnetic activity. This behavior can be explained by seasonal trends in the nighttime downward heat flux due to conjugate photoelectrons. Moreover, model results indicate that a factor of about three increase in heat inflow during equinox relative to solstice is required to raise the electron temperature to a given level. This is a consequence of the higher electron densities at the Te peak near equinox. The Te peak occurs on field lines which thread the outer plasmasphere in the vicinity if the plasmapause and thus can be used as a tracer of the plasmapause position.

Fok, M.-C.↗
NASA NTRS1995

Equatorial Kelvin wave variability during 1992 and 1993

Temperature and ozone data from the Microwave Limb Sounder (MLS) instrument on Upper Atmosphere Research Satellite (UARS) are used to analyze the variability of Kelvin wave activity during the first two years of the UARS mission. The analysis is carried out using the asynoptic mapping technique. Time frequency plots for zonal wavenumbers 1 and 2, at two heights representing the middle stratosphere and the stratopause, respectively, are used to analyze the temporal variability of the waves, and its possible relationship to the equatorial quasi-biennial oscillation (QBO) and semiannual oscillation (SAO). Kelvin wave activity reaches a maximum during the solstice seasons and almost disappears during the equinoxes, in agreement with previous studies. Eastward propagating variance is estimated for wave periods from 4 to 20 days, at all UARS pressure surfaces currently available for MLS. The semiannual modulation of variance is observed to extend down to the lower limits of the height ranges of the temperature and ozone retrievals. Furthermore, a superposed QBO modulation is detected up to the stratopause. Comparison between the variance in eastward propagating waves and the mean zonal wind shows a possible participation of kelvin waves in the forcing of the QBO. At the stratopause the role of Kelvin waves in forcing the SAO appears to be limited, in agreement with previous results. Between the 21-hPa and 4.6-hPa surfaces there appears to be a transition zone where there is no clear relationship between Kelvin wave activity and mean zonal flow acceleration.

Canziani, Pablo O.↗
NASA NTRS2017

How Long Do Satellites Need to Overlap? Evaluation of Climate Data Stability from Overlapping Satellite Records

Sensors on satellites provide unprecedented understanding of the Earth's climate system by measuring incoming solar radiation, as well as both passive and active observations of the entire Earth with outstanding spatial and temporal coverage. A common challenge with satellite observations is to quantify their ability to provide well-calibrated, long-term, stable records of the parameters they measure. Ground-based intercomparisons offer some insight, while reference observations and internal calibrations give further assistance for understanding long-term stability. A valuable tool for evaluating and developing long-term records from satellites is the examination of data from overlapping satellite missions. This paper addresses how the length of overlap affects the ability to identify an offset or a drift in the overlap of data between two sensors. Ozone and temperature data sets are used as examples showing that overlap data can differ by latitude and can change over time. New results are presented for the general case of sensor overlap by using Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) and Solar Stellar Irradiance Comparison Experiment (SOLSTICE) solar irradiance data as an example. To achieve a 1 % uncertainty in estimating the offset for these two instruments' measurement of the Mg II core (280 nm) requires approximately 5 months of overlap. For relative drift to be identified within 0.1 %/yr uncertainty (0.00008 W/sq m/nm/yr), the overlap for these two satellites would need to be 2.5 years. Additional overlap of satellite measurements is needed if, as is the case for solar monitoring, unexpected jumps occur adding uncertainty to both offsets and drifts; the additional length of time needed to account for a single jump in the overlap data may be as large as 50 % of the original overlap period in order to achieve the same desired confidence in the stability of the merged data set. Results presented here are directly applicable to satellite Earth observations. Approaches for Earth observations offer additional challenges due to the complexity of the observations, but Earth observations may also benefit from ancillary observations taken from ground-based and in situ sources. Difficult choices need to be made when monitoring approaches are considered; we outline some attempts at optimizing networks based on economic principles. The careful evaluation of monitoring overlap is important to the appropriate application of observational resources and to the usefulness of current and future observations.

climate data records↗
NASA NTRS1999

Mars Global Surveyor Thermal Emission Spectrometer (TES) Observations: Atmospheric Temperatures During Aerobraking and Science Phasing

Between September 1997, when the Mars Global Surveyor spacecraft arrived at Mars, and September 1998 when the final aerobraking phase of the mission began, the Thermal Emission Spectrometer (TES) has acquired an extensive data set spanning approximately half of a Martian year. Nadir-viewing spectral measurements from this data set within the 15-micrometers CO2 absorption band are inverted to obtain atmospheric temperature profiles from the surface up to about the 0.1 mbar level. The computational procedure used to retrieve the temperatures is presented. Mean meridional cross sections of thermal structure are calculated for periods of time near northern hemisphere fall equinox, winter solstice, and spring equinox, as well as for a time interval immediately following the onset of the Noachis Terra dust storm. Gradient thermal wind cross sections are calculated from the thermal structure. Regions of possible wave activity are identified using cross sections of rms temperature deviations from the mean. Results from both near-equinox periods show some hemispheric asymmetry with peak eastward thermal winds in the north about twice the magnitude of those in the south. The results near solstice show an intense circumpolar vortex at high northern latitudes and waves associated with the vortex jet core. Warming of the atmosphere aloft at mid-northern latitudes suggests the presence of a strong cross-equatorial Hadley circulation. Although the Noachis dust storm did not become global in scale, strong perturbations to the atmospheric structure are found, including an enhanced temperature maximum aloft at high northern latitudes resulting from intensification of the Hadley circulation. TES results for the various seasonal conditions are compared with published results from Mars general circulation models, and generally good qualitative agreement is found.

Conrath, Barney J.↗
NASA NTRS2022

Seasonal Variation of Thermospheric Composition Observed by NASA GOLD

We examine characteristics of the seasonal variation of thermospheric composition using column number density ratio ∑O/N(2) observed by the NASA Global Observations of Limb and Disk (GOLD) mission from low-mid to mid-high latitudes. We also use ∑O/N(2) derived from the Global Ultraviolet Imager (GUVI) limb measurements onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite and estimated by the NRLMSISE-00 empirical model to aid our investigation. We found that the ∑O/N(2) seasonal variation is hemispherically asymmetric: in the southern hemisphere, it exhibits the well-known annual and semiannual pattern, with highs near the equinoxes, and primary and secondary lows near the solstices. In the northern hemisphere, it is dominated by an annual variation, with a minor semiannual component with the highs shifting toward the wintertime. We also found that the durations of the December and June solstice seasons in terms of ∑O/N(2) are highly variable with longitude. Our hypothesis is that ion-neutral collisional heating in the equatorial ionization anomaly region, ion drag, and auroral Joule heating play substantial roles in this longitudinal dependency. Finally, the rate of change in ∑O/N(2) from one solstice season to the other is dependent on latitude, with more dramatic changes at higher latitudes.

thermosphere↗