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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Studies of high latitude mesospheric turbulence by radar and rocket. II - Measurements of small scale turbulence

Measurements of mesospheric small scale turbulence and associated larger scale wave structures were obtained from rocket probe flights during equinox in spring 1985. The measurements were verified by data from the mesosphere-stratosphere-troposphere radar at Poker Flat, Alaska. Electron density irregularities down to an altitude of about 62 km and fluctuations in positive ion density in the altitude region from 50 to 90 km were measured. Turbulence in the inertial subrange was observed at heights where the fluctuations generally were largest. Measurement of background electron density exhibited gradients relative to the monotonically increasing density profile, suggesting the presence of large amplitude wave motions transporting the plasma by mixing. The radar detected the occurrence of 1-3 km wavelike perturbations superimposed on a 7-km wave in the wind velocity field. It is suggested that the 1-3 km waves are more important in the transport of energy and momentum and in the production of turbulence in the lower mesosphere.

Blood, S. P.↗
NASA NTRS1993

Temperature, N2, and N density profiles of Triton's atmosphere - Observations and model

Improved analysis of the Voyager Ultraviolet Spectrometer observations of the solar occultation by Triton yields the isothermal temperature and N2 number densities in the altitude range 475-675 km. The signature of atomic nitrogen in the occultation spectra is identified, its density profile is derived, and an experimental value of the escape rate of N atoms is given. The one-dimensional thermal conductivity equation for a spherical atmosphere is solved, taking into account CO heating and cooling and heating by precipitating electrons, solar radiation, and chemical effects. Finally, profiles of number densities of N, H2, and H are calculated.

Krasnopolsky, V. A.↗
NASA NTRS1972

A global empirical model of thermospheric composition based on OGO-6 mass spectrometer measurements.

A global empirical model for magnetically quiet conditions has been developed to describe longitudinally averaged OGO-6 N2, O, and He densities (in the altitude range 400 to 600 km) by means of an expansion into spherical harmonics. The annual asymmetric component in N2 density corresponds to an increase of about 400 K between winter and summer poles, which is about a factor of three greater than in the Jacchia model. However, the corresponding oxygen component at satellite altitudes reflects an increase between winter and summer comparable to that in the Jacchia model; this implies that at 120 km atomic oxygen increases by more than a factor of two between summer and winter poles. The amplitude of the symmetric semiannual component in N2 is larger at the poles than the equator. At the poles, the N2 variation corresponds to a temperature decrease of about 70 K from mid-April to mid-July. At low latitudes, the daily temperature maximum occurs close to 16 hours local time, nearly in agreement with radar backscatter observations.

Hedin, A. E.↗
NASA NTRS1991

Large scale lunar horizon glow and a high altitude lunar dust exosphere

All three Apollo 17 astronauts sketched a `lunar horizon glow', seen from orbit above the moon. It is shown that the shape of the glow is compatible with scattering of sunlight off of gas or dust at high altitudes above the moon. The present mathematical modeling best simulates the glow with submicron dust grains whose spatial density varies with altitude above the moon as exp(-H/H(s)), where H(s) is in the range of 5 to 20 km. These dust grains are probably electrically charged and ejected above the lunar surface by local electric fields.

Zook, Herbert A.↗
NASA NTRS2017

Nightside Ionosphere of Mars: Composition, Vertical Structure, and Variability

We provide an overview of the composition, vertical structure, and variability of the nightside ionosphere of Mars as observed by Mars Atmosphere and Volatile EvolutioN (MAVEN)'s Neutral Gas and Ion Mass Spectrometer (NGIMS) through 19 months of the MAVEN mission. We show that O+2 is the most abundant ion down to ∼130 km at all nightside solar zenith angles (SZA). However, below 130 km NO+ is the most abundant ion, and NO+ densities increase with decreasing altitude down to at least 120 km. We also show how the densities of the major ions decrease with SZA across the terminator. At lower altitudes the O+2 and CO+2 densities decrease more rapidly with SZA than the NO+ and HCO+ densities, which changes the composition of the ionosphere from being primarily O+2 on the dayside to being a mixture of O+2, NO+, and HCO+ on the nightside. These variations are in accord with the expected ion-neutral chemistry, because both NO+ and HCO+ have long chemical lifetimes. Additionally, we present median ion density profiles from three different nightside SZA ranges, including deep on the nightside at SZAs greater than 150∘ and discuss how they compare to particle precipitation models. Finally, we show that nightside ion densities can vary by nearly an order of magnitude over month long timescales. The largest nightside densities were observed at high northern latitudes during winter and coincided with a major solar energetic particle event.

Mars↗
NASA NTRS1999

Global Core Plasma Model

Over 40 years of ground and spacecraft plasmaspheric measurements have resulted in many statistical descriptions of plasmaspheric properties. In some cases, these properties have been represented as analytical descriptions that are valid for specific regions or conditions. For the most part, what has not been done is to extend regional empirical descriptions or models to the plasmasphere as a whole. In contrast, many related investigations depend on the use of representative plasmaspheric conditions throughout the inner magnetosphere. Wave propagation, involving the transport of energy through the magnetosphere, is strongly affected by thermal plasma density and its composition. Ring current collisional and wave particle losses also strongly depend on these quantities. Plasmaspheric also plays a secondary role in influencing radio signals from the Global Positioning System satellites. The Global Core Plasma Model (GCPM) is an attempt to assimilate previous empirical evidence and regional models for plasmaspheric density into a continuous, smooth model of thermal plasma density in the inner magnetosphere. In that spirit, the International Reference Ionosphere is currently used to complete the low altitude description of density and composition in the model. The models and measurements on which the GCPM is currently based and its relationship to IRI will be discussed.

Gallagher, Dennis L.↗
NASA NTRS1999

Empirical Modeling of the Plasmasphere

Over 40 years of ground and spacecraft plasmaspheric measurements have resulted in many statistical descriptions of plasmaspheric properties. In some cases, these properties have been represented as analytical descriptions that are valid for specific regions or conditions. For the most part, what has not been done is to extend regional empirical descriptions or models to the plasmasphere as a whole. In contrast, many related investigations depend on the use of representative plasmaspheric conditions throughout the inner magnetosphere. Wave propagation, involving the transport of energy through the magnetosphere, is strongly affected by thermal plasma density and its composition. Ring current collisional and wave particle losses also strongly depend on these quantities, Plasmaspheric also plays a secondary role in influencing radio signals from the Global Positioning System satellites. The Global Core Plasma Model (GCPM) is an attempt to assimilate previous empirical evidence and regional models for plasmaspheric density into a continuous, smooth model of then-nal plasma density in the inner magnetosphere. In that spirit, the International Reference Ionosphere is currently used to complete the low altitude description of density and composition in the model. The models and measurements on which the GCPM is currently based and its relationship to IRI will be discussed.

Gallagher, Dennis L.↗
NASA NTRS2001

NRLMSISE-00 Empirical Model of the Atmosphere: Statistical Comparisons and Scientific Issues

The new NRLMSISE-00 model and the associated NRLMSIS database now include the following data: (1) total mass density from satellite accelerometers and from orbit determination, including the Jacchia and Barlier data; (2) temperature from incoherent scatter radar, and; (3) molecular oxygen number density, [O2], from solar ultraviolet occultation aboard the Solar Maximum Mission (SMM). A new component, 'anomalous oxygen,' allows for appreciable O(+) and hot atomic oxygen contributions to the total mass density at high altitudes and applies primarily to drag estimation above 500 km. Extensive tables compare our entire database to the NRLMSISE-00, MSISE-90, and Jacchia-70 models for different altitude bands and levels of geomagnetic activity. We also investigate scientific issues related to the new data sets in the NRLMSIS database. Especially noteworthy is the solar activity dependence of the Jacchia data, with which we investigate a large O(+) contribution to the total mass density under the combination of summer, low solar activity, high latitudes, and high altitudes. Under these conditions, except at very low solar activity, the Jacchia data and the Jacchia-70 model indeed show a significantly higher total mass density than does MSISE-90. However, under the corresponding winter conditions, the MSIS-class models represent a noticeable improvement relative to Jacchia-70 over a wide range of F(sub 10.7). Considering the two regimes together, NRLMSISE-00 achieves an improvement over both MSISE-90 and Jacchia-70 by incorporating advantages of each.

Aikin, A. C.↗
NASA NTRS2010

Updating Mars-GRAM to Increase the Accuracy of Sensitivity Studies at Large Optical Depths

The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM s perturbation modeling capability is commonly used, in a Monte-Carlo mode, to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL). During the Mars Science Laboratory (MSL) site selection process, it was discovered that Mars-GRAM, when used for sensitivity studies for MapYear=0 and large optical depth values such as tau=3, is less than realistic. From the surface to 80 km altitude, Mars-GRAM is based on the NASA Ames Mars General Circulation Model (MGCM). MGCM results that were used for Mars-GRAM with MapYear set to 0 were from a MGCM run with a fixed value of tau=3 for the entire year at all locations. This has resulted in an imprecise atmospheric density at all altitudes. As a preliminary fix to this pressure-density problem, density factor values were determined for tau=0.3, 1 and 3 that will adjust the input values of MGCM MapYear 0 pressure and density to achieve a better match of Mars-GRAM MapYear 0 with Thermal Emission Spectrometer (TES) observations for MapYears 1 and 2 at comparable dust loading. Currently, these density factors are fixed values for all latitudes and Ls. Results will be presented from work being done to derive better multipliers by including variation with latitude and/or Ls by comparison of MapYear 0 output directly against TES limb data. The addition of these more precise density factors to Mars-GRAM 2005 Release 1.4 will improve the results of the sensitivity studies done for large optical depths.

Justh, Hiliary L.↗
NASA NTRS1984

Ionospheric electron density irregularities observed by satellite-to-satellite, dual-frequency, low-low Doppler tracking link

A low-low, satellite-to-satellite, dual-frequency, Doppler tracking experiment was performed. The data are analyzed here for irregularities in electron density at the altitude of 212 km. The differential Doppler data with the relative motion term removed are integrated to obtain a representation of the electron density variation along the satellite path. Well-known large-scale features such as the equatorial geomagnetic anomaly and day/night ionization level differences are clearly observed in the integrated data. The larger crest of the morning geomagnetic anomaly is seen to occur in the southern (winter) hemisphere in agreement with previous observations. In addition, a sharp peak in the electron density at the day-to-night transition point is observed in two consecutive revolutions. This effect may be due to the previously postulated atmospheric shock wave generated by supersonic motion of the terminator.

Estes, R. D.↗
NASA NTRS1985

Positive ion composition and derived particle heating in the lower auroral ionosphere

Two E11a rocket flights in salvo B (launched on November 16, 1980) and A2 (launched on November 30, 1980), which provide positive ion composition, total and partial ion density, and electron density in the altitude range 60-170 km above Kiruna under conditions of moderate and strong magnetic disturbance, are examined. It is shown that the ionization sources are predominantly precipitating electrons in salvo B and precipitating protons in salvo A2. Under winter-time auroral conditions the characteristics of the positive ion composition are large NO(+)/O2(+) density ratios, with maximum values of 20 at 118 km in salvo B and 100 at 100 km in salvo A2, respectively. The transition from NO(+) to proton hydrates is found at an altitude of 79 km in salvo B and 76 km in salvo A2. The calculated O(+) and N(+) densities are in good agreement with model calculations and from these calculations it is concluded that 28(+) is mainly N2(+) above 110 km in salvo B and above 105 km in salvo A2, and Si(+) below these altitudes. By altitude integration of the ion-electron pair production, the energy flux of precipitating particles is found to have values of 0.85 mW/sq m and 1.0 mW/sq m in salvoes B and A2, respectively.

Kopp, E.↗
NASA NTRS1983

GSFC optical ozonesonde results during the Gap, France, intercomparisons, June 1981

O3 soundings made with balloon-borne optical sensors during the French Intercomparison Ozone Campaign in June, 1981, are reported. The GSFC four-channel UV-filter-photometer ozonesonde designed for the Super Loki rocket was attached to the gondola roof for redundant O3-density measurements at altitudes of 22-32 km, using the 300 and 303-nm filters. Sensor calibration, data processing, input constants, and vertical O3-distribution calculations are discussed. The density profiles for three legs of the flight, calculated using Bass or Vigroux cross sections, agreed within a standard error of 1.4 percent for each channel, but showed a consistent 4-5 percent (significant) difference between channels. Total average O3-column amounts determined by combining the GSFC data with ECC measurements for altitudes below 21 km were in good agreement with bias-corrected TOMS data from Nimbus-VII and with ground-based data from the Observatoire de Haute-Provence at Mt. Chiran, when the latter were computed using the pre-campaign calibration. A 9-percent discrepancy arose when the Chiran data were corrected for a post-campaign recalibration of the Dobson spectrophotometer.

Krueger, A. J.↗
NASA NTRS1983

O(+) ions in the polar wind

A semikinetic model was used to describe the steady state collisionless flow of the polar wind along diverging geomagnetic field lines at high latitues. Emphasis was given to studying the behavior of O(+) ions for a wide range of boundary conditions at the baropause (4500 km). The main result obtained was that for high electron temperatures Te = about 10,000 K) O(+) is not gravitationally bound and significant escape fluxes (about 10 to the 7th/sq cm sec) of suprathermal (2eV) O(+) ions occur. The O(+) flow is supersonic over most of the altitude range considered, and O(+) Mach numbers as large as 20 are predicted at 10 earth radii. Also, depending on the boundary conditions, the O(+) density can be comparable to or greater than the H(+) density at high altitudes above the baropause when the electron temperature is high.

Barakat, A. R.↗
NASA NTRS1999

Singular Plasma Disturbance in the Low-Latitude F Region

We describe here a new phenomenon characterized by unusual patterns of ion drifts inside ion density depletion regions observed by the AE-E satellite in the low-latitude F region. In about 30 depletions, vertical ion drift relative to the background was upward on the western sides, downward on the eastern sides, and zero near the middle where the density depletion was greatest. These drift characteristics are distinct from those observed in plasma bubble depletions. The structures reported here were observed on circular orbits below 300 km altitude and had density depletions of up to 2 orders of magnitude or more below the ambient ion density. The upward and downward drift excursions were up to 200 m/s relative to the background. Almost all these structures were observed over oceans or near coasts and largely between +/- 10 deg and +/- 30 deg clip latitude. The structures were observed mostly as isolated, single depletion regions with the majority of them about 250 km wide in the east-west direction. They occurred during quiet magnetic conditions with near-equal occurrence frequencies in the premidnight and postmidnight periods. The characteristic density and drift signatures indicate westward propagating disturbances in which the bottomside F layer is first lifted and then returned back to its original position, leaving the ionosphere undisturbed after the disturbance passes by. The estimated speed of these disturbances is of the order of 200 m/s. These unique solitary plasma disturbances, which we designate as singular plasma disturbances, are associated with a propagating source of E x B drift, not driven by neutral perturbations at the altitude of observation.

Singh, Sardul↗
NASA NTRS2020

Validation of SAGE III/ISS Solar Ozone Data with Correlative Satellite and Ground Based Measurements

The Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III/ISS) was launched on February 19, 2017 and began routine operation in June 2017. The first two years of SAGE III/ISS (v5.1) solar ozone data were evaluated by using correlative satellite and ground-based measurements. Among the three (MES, AO3, and MLR) SAGE III/ISS solar ozone products, AO3 ozone shows the best accuracy and precision, with mean biases less than 5% for altitudes ~15–55 km in the mid-latitudes and ~20–55 km in the tropics. In the lower stratosphere and upper troposphere, AO3 ozone shows high biases that increase with decreasing altitudes and reach ~10% near the tropopause. Preliminary studies indicate that those high biases primarily result from the contributions of the oxygen dimer (O4) not being appropriately removed within the ozone channel. The precision of AO3 ozone is estimated to be ~3% for altitudes between 20 and 40 km. It degrades to ~10–15% in the lower mesosphere (~55 km), and ~20–30% near the tropopause. There could be an altitude registration error of ~100 meter in the SAGE III/ISS auxiliary temperature and pressure profiles. This, however, does not affect retrieved ozone profiles in native number density on geometric altitude coordinates. In the upper stratosphere and lower mesosphere (~40–55 km) the SAGE III/ISS (and SAGE II) sunset ozone values are systematically higher than sunrise data by ~5–8% which are almost twice larger than what observed by other satellites or model predictions. This feature needs further study.

H J Wang↗
NASA NTRS1923

Standard atmosphere

This report was prepared at the request of the National Advisory Committee for Aeronautics and discusses the need of a standard set of values of pressure, temperature and density at various altitudes and points out the desirability of adopting such values as are most in accord with actual average conditions, in order that corrections in individual cases may be as small as possible. To meet this need, so far as the united states is concerned, all free-air observations obtained by means of kites and balloons at several stations in this country near latitude 40 degrees N., have been used, and average values of pressure, temperature, and density, based upon those observations, have been determined for summer, winter, and the year, and for all altitudes up to 20,000 meters (65,000 feet). These values are presented in tables and graphs in both metric and english units; and in the tables of densities there are also included values of density for other parts of the world, more particularly for Europe. A comparison with these values shows that, except in the lowest levels, the agreement is very satisfactory.

Gregg, Willis Ray↗
NASA NTRS1981

On the maintenance of the Venus nightside ionosphere - Electron precipitation and plasma transport

The relative contributions of electron precipitation and transport of dayside plasma to the maintenance of the Venus nightside ionosphere during the long Venusian night are investigated based on simultaneous Pioneer Venus Orbiter Retarding Potential Analyzer measurements of suprathermal electron fluxes and plasma densities. In about 20 orbits, the nightside integral electron flux of electrons with energies between 5 and 45 eV is observed to be relatively constant in time and altitude, while plasma density is observed to vary by a factor of 10 or more with no correlation with the electron flux. Ionization rates and ion density height profiles are computed for O(+) and O2(+) as a function of magnetic dip angle based on a typical electron spectrum, or a downward flux of O(+) ions. Comparison of the computed profiles with the measured median O(+) and O2(+) density profiles reveals that the measured profiles can only be reproduced by a downward flux of O(+) equal to about 10 to the 8th/sq cm per sec; suprathermal electron energy distributions produce O2(+) and O(+) levels only about half and one tenth those usually observed, respectively. It is thus concluded that transport of O(+) ions from the dayside Venus ionosphere is responsible for approximately 75% of the typical nightside ionization, with variations in O(+) transport mechanism responsible for most of the observed nightside density variations. The remaining ionization is attributed to suprathermal electrons, which contribute principally to the O2(+) peak.

Spenner, K.↗
NASA NTRS1923

Performance of Maybach 300-horsepower airplane engine

This report contains the results of a test made upon a Maybach Engine in the altitude chamber of the Bureau of Standards, where controlled conditions of temperature and pressure can be made the same as those of the desired altitude. The results of this test lead to the following conclusions: from the standpoint of thermal efficiency the full-load performance of the engine is excellent at densities corresponding to altitudes up to and including 15,000 feet. The brake mean effective pressure is rather low even at wide-open throttle. This tends to give a high weight per horsepower, in as much as the weight of many engine parts is governed by the size rather than the power of the engine. At part load the thermal efficiency of the engine is low. Judged on a basis of performance the engine's chief claim to interest would appear to lie in the carburetor design, which is largely responsible excellent full-load efficiency and for its poor part-load efficiency.

Sparrow, S W↗