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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Zonal winds near Venus' cloud top level - A model study of the interaction between the zonal mean circulation and the semidiurnal tide

The Holton (1982) wave-mean flow interaction model's primitive equation is presently adapted in order to clarify the interaction between the semidiurnal tide and the thermally driven mean meridional circulation near cloud top level. The model is found to produce midlatitude jets whose structure is insensitive to vertical shear of the background angular velocity, both above and below cloud top level; a sensitivity to background angular velocity at cloud top level, however, is noted. Agreement between the model tide and either the observed one or that generated by the more detailed calculations of Pechmann and Ingersoll (1984) is found to be greatest when the background angular velocity at the jet level is of the order of 30 percent larger than that which is observed.

Baker, Nancy L.↗
NASA NTRS1990

The interaction of horizontal eddy transport and thermal drive in the stratosphere

The two processes that determine the average state of the circulation; i.e., horizontal eddy transport and thermal dissipation, are examined, and the effects of their interaction on circulation and on tracer distribution in the stratosphere are investigated using barotropic calculations on the sphere. It is shown that eddy advection tends to homogenize the meridional gradient Q at low latitudes, while thermal dissipation restores the gradient after episodes of mixing.

Salby, Murry L.↗
NASA NTRS2016

Active CryoCubeSat

The Active CryoCubeSat project will demonstrate an advanced thermal control system for a 6-Unit (6U) CubeSat platform. A miniature, active thermal control system, in which a fluid is circulated in a closed loop from thermal loads to radiators, will be developed. A miniature cryogenic cooler will be integrated with this system to form a two-stage thermal control system. Key components will be miniaturized by using advanced additive manufacturing techniques resulting in a thermal testbed for proving out these technologies. Previous CubeSat missions have not tackled the problem of active thermal control systems nor have any past or current CubeSat missions included cryogenic instrumentation. This Active CryoCubeSat development effort will provide completely new capacities for CubeSats and constitutes a major advancement over the state-of-the-art in CubeSat thermal control.

CubeSat↗
NASA NTRS1987

A simplified model of the modified Hadley circulation

In this paper, a simplified model of modified Hadley circulation that is amenable to analysis is developed to find the low-latitude upper-tropospheric circulation which would exist in the absence of transient eddies. The model is developed as a perturbation of the ideal Hadley circulation solution due to zonally assymmetric thermal forcing and is solved semianalytically. The modified Hadley circulation, found using forcing derived from observed outgoing long-wave radiation, exhibits some similarities to observed features of the tropical and subtropical time-mean upper-tropospheric flow, particularly with regard to the velocity potential.

Schneider, Edwin K.↗
NASA NTRS2015

Opportunity In Situ Geologic Context of Aqueous Alteration Along Offsets in the Rim of Endeavour Crater

Mars Exploration Rover Opportunity traversed 7.9 km and 27 degrees of arc along the rim of the 22 km-diameter Noachian "Endeavour" impact crater since its arrival 1200 sols ago. Areas of aqueous and low-grade thermal alteration, and changes in structure, attitude, and macroscopic texture of outcrops are notable across several discontinuities between segments of the crater rim. The discontinuities and other post-impact joints and fractures coincide with sites of apparent deep fluid circulation processes responsible for thermal and chemical alteration of local outcrops.

Crumpler, L. S.↗
NASA NTRS1988

Principal components of the North American summer temperature field and the antecedent oceanic and atmospheric conditions

The North American summer temperature field is evaluated in terms of the preceding patterns of the ocean and atmosphere. It is found that the planetary scale circulation associated with the thermal field over the western tropical Pacific and the ocean-atmosphere interaction over the central North Pacific-Aleutian region are important in determining the summer surface temperature pattern over North America. Also, evidence is presented for the possible impact of the El Nino-Southern Oscillation on the summer circulation pattern. It is suggested that by using the principal components, the predictability of regional circulation can be evaluated as a linear combination of independent sources of variability.

Park, Chung-Kyu↗
NASA NTRS2000

In-Situ Environmental Measurements Needed for Future Mars Missions

Existing measurements and modeling studies indicate that the climate and general circulation of the thin, predominately CO2 Martian atmosphere are characterized by large-amplitude variations with a wide range of spatial and temporal scales. Remote sensing observations from Earth-based telescopes and the Mariner 9, Viking, Phobos, and Mars Global Surveyor (MGS) orbiters show that the prevailing climate includes large-scale seasonal variations in surface and atmospheric temperatures (140 to 300 K), dust optical depth (0.15 to 1), and water vapor (10 to 100 precipitable microns). These observations also provided the first evidence for episodic regional and global dust storms that produce even larger perturbations in the atmospheric thermal structure and general circulation. In-situ measurements by the Viking and Mars Pathfinder Landers reinforced these conclusions, documenting changes in the atmospheric pressure on diurnal (5%) and seasonal (>20%) time scales, as well as large diurnal variations in the near-surface temperature (40 to 70 K), wind velocity (0 to 35 m/s), and dust optical depth (0.3 to 6). These in-situ measurements also reveal phenomena with temporal and spatial scales that cannot be resolved from orbit, including rapid changes in near-surface temperatures (+/- 10 K in 10 seconds), large near-surface vertical temperature gradients (+/- 15 K/meter), diurnally-varying slope winds, and dust devils . Modeling studies indicate that these changes are forced primarily by diurnal and seasonal variations in solar insolation, but they also include contributions from atmospheric thermal tides, baroclinic waves (fronts), Kelvin waves, slope winds, and monsoonal flows from the polar caps.

Crisp, D.↗
NASA NTRS1980

Zonal and meridional circulation of the lower atmosphere of Venus determined by radio interferometry

The results of the Pioneer Venus differential long-baseline interferometry experiment are presented. The velocity component of the Pioneer probes as they fell to the surface of Venus was calculated from the Doppler shift of the received signal, and the other two orthogonal components were determined by long-baseline interferometry. The ambient wind velocity was about 1 m/s or less near the surface of the planet and about 100 m/s at an altitude of about 65 km at all four probe locations. Strata of high wind shear were found at altitudes of 15, 45, and 60 km. The wind velocity was always directed within a few degrees of due west except at a few km above the surface. The dominant motion of the lower atmosphere seems to be a retrograde zonal rotation, and eddies appear to account for most of the instantaneous meridional velocity. The data suggest that, within the clouds, a thermally driven mean meridional circulation is superimposed upon the much more rapid zonal rotation.

Counselman, C. C., III↗
NASA NTRS1972

The stable auroral red arc of October 31 - November 1, 1968 and its interaction with the neutral atmosphere

Satellite observations of electron temperature and the topside electron density structure are used to calculate the red arc according to the thermal conduction model. In this model, energy from the magnetosphere flows in the electron gas along geomagnetic field lines into the ionosphere. This energy heats the ambient F-region electrons sufficiently to excite the oxygen atoms to the O I(1D) level by collisional impact giving rise to the 6300 A emission characteristic of the arc. For the 31 October/1 November 1968 red arc, the calculated emission rate, geographical position, and horizontal extent of the red arc are in agreement with the photometric data obtained by airglow observatories. Almost all of the energy conducted into the red arc is ultimately transferred to the neutral gas through elastic and inelastic collisions. This energy drives a large thermal cell and the circulation extends the influence of the arc thousands of kilometers beyond the region of direct heat input. The calculated neutral gas temperature response to electron heating within the arc is small.

Roble, R. G.↗
NASA NTRS1973

Radiation measurements from polar and geosynchronous satellites

During the 1960's, radiation budget measurements from satellites have allowed quantitative study of the global energetics of our atmosphere-ocean system. A continuing program is planned, including independent measurement of the solar constant. Thus far, the measurements returned from two basically different types of satellite experiments are in agreement on the long term global scales where they are most comparable. This fact, together with independent estimates of the accuracy of measurement from each system, shows that the energy exchange between earth and space is now measured better than it can be calculated. Examples of application of the radiation budget data were shown. They can be related to the age-old problem of climate change, to the basic question of the thermal forcing of our circulation systems, and to the contemporary problems of local area energetics and computer modeling of the atmosphere.

Vonderhaar, T. H.↗
NASA NTRS1981

Solar-energy heats a transportation test center--Pueblo, Colorado

Petroleum-base, thermal energy transport fluid circulating through 583 square feet of flat-plate solar collectors accumulates majority of energy for space heating and domestic hot-water of large Test Center. Report describes operation, maintenance, and performance of system which is suitable for warehouses and similar buildings. For test period from February 1979 to January 1980, solar-heating fraction was 31 percent, solar hot-water fraction 79 percent.

Source record↗
NASA NTRS1981

Superrotation planetary atmospheres: Mechanical analogy, angular momentum budget and simulation of the spin up process

Superrotation rates observed in planetary atmospheres are analyzed based on the concept of a thermally driven zonally symmetric circulation. Specifically, how this superrotation is produced and maintained against the tendency for friction to oppose differential motions between the atmosphere and the underlying planet is addressed. The time evolution of a fluid leading from corotation under uniform heating to superrotation under globally nonuniform heating is simulated using a three dimensional zonally symmetric spectral model and Laplace transformation. The increased tendency toward geostrophy combined with the increase of surface pressure toward the poles (due to meridional mass transport), induces the atmosphere to subrotate temporarily at lower altitudes. The resulting viscous shear near the surface thus permits angular momentum to flow from the planet into the atmosphere where it propagates upwards and, combined with the change in moment of inertia, produces large superrotation rates at higher viscosities.

Mayr, H. G.↗
NASA NTRS1987

Study of internal gravity waves in the meteor zone

An important component of the dynamical regime of the atmosphere at heights near 100 km are internal gravity waves (IGW) with periods from about 5 min to about 17.5 hrs which propagate from the lower atmospheric layers and are generated in the uppermost region of the atmosphere. As IGW propagate upwards, their amplitudes increase and they have a considerable effect on upper atmospheric processes: (1) they provide heat flux divergences comparable with solar heating; (2) they influence the gaseous composition and produce wave variations of the concentrations of gaseous components and emissions of the upper atmosphere; and (3) they cause considerable acceleration of the mean stream. It was concluded that the periods, wavelengths, amplitudes and velocities of IGW propagation in the meteor zone are now measured quite reliably. However, for estimating the influence of IGW on the thermal regime and the circulation of the upper atmosphere these parameters are not as important as the values of wave fluxes of energy, heat, moment and mass.

Gavrilov, N. M.↗
NASA NTRS1993

Equatorial superrotation in a slowly rotating GCM - Implications for Titan and Venus

The GISS GCM is used here to examine the hypothesis that equatorial superrotation on slowly rotating planets is sensitive to the nature of the vertical radiative heating profile and can exist in the absence of diurnally varying forcing. The general circulation, diabatic heating, and thermal structure produced in the experiments are described and the heat and angular momentum budgets and energy cycles are analyzed to understand the factors conducive to equatorial superrotation. The implications of the results for future planetary missions are addressed.

Del Genio, Anthony D.↗
NASA NTRS1993

The Amazon river breeze and the local boundary layer. I - Observations

Observations of the diurnal evolution of the planetary boundary layer over the Amazon rain forest, made at sites close to the confluence of the Solimoes and Negro rivers (approximately at 3 deg S, 60 deg W) near Manaus, Amazonas, Brazil, show the existence of a diurnal rotation of the wind near the surface and the frequent presence of low-level nocturnal wind maxima. These circulations are shown to be plausibly explained as elements of a river and land breeze circulation induced by the thermal contrast between the rivers and the adjacent forest.

De Oliveira, Amauri P.↗
NASA NTRSDate not supplied

Quiet Spacecraft Cabin Ventilation Fan Development: Motivation and Context

It is important to control acoustical noise aboard crewed space vehicles and space habitats to provide a satisfactory environment for voice communications, alarm audibility, and restful sleep, and to minimize the risk for hearing loss and annoyance. As with most noise control efforts, it is best to control the noise at the source, and for spaceflight vehicles these are typically the fans associated with the Environmental Control and Life Support (ECLS) system. These include air ventilation fans, such as the main air conditioning fan (the ‘cabin fan’), intermodule ventilation (IMV) fans, air revitalization fans (for removal of carbon dioxide and trace contaminates), and thermal cooling fans. Thermal cooling pumps that circulate cooling fluid are another significant noise source in spaceflight vehicles, but these are outside of the scope of this paper. Throughout the history of crewed spaceflight, there have been issues with noise from ECLS ventilation fans. In the Apollo Command Module (CM) the crew would turn off the CM cabin fan once in orbit and use the backup suit-loop fan for ventilation because noise from the cabin fan interfered with communications and was an annoyance. On the Space Shuttle the ventilation system underwent significant redesign, including the addition of ventilation system mufflers, with resulting noise levels that were still too-high for long-duration missions. In the early years of International Space Station (ISS) operations, acoustical noise was one of the top two habitability issues, resulting in significant noise controls (along with significant cost and crew-time impacts) being implemented on-orbit on many fans, with significant noise reductions realized only after replacing noisy fans with fans of a quieter design, funded by the ISS Program. And, with the spaceflight vehicles and habitats currently being developed, there are again concerns with noise levels from ventilation fans. In the Orion vehicle, additional duct mufflers needed to be added to address the cabin fan noise. The Gateway’s Habitation and Logistics Outpost (HALO) module and low-Earth orbit (LEO) Freeflyer habitats are currently working to solve this problem. This will also be an issue for lunar and Mars spaceflight vehicles, space suits, and surface habitats. In an effort to address this problem, NASA is working to leverage the technology developed in its Aeronautics Research Mission Directorate (ARMD), specifically at the Glenn Research Center (GRC), to design highly efficient and quiet fans for reducing community noise levels from civilian aircraft. This technology was created over decades of research and development, and was proven to be effective at reducing aircraft noise levels. The current collaboration across NASA Centers, including HQ, GRC, and the Johnson Space Center (JSC) in this area is the first effort at re-purposing these tools, i.e. design codes and techniques, developed for high Reynolds number fans to spaceflight vehicle and habitat, low Reynolds number, fans. This paper will discuss the need for transfer of aeronautics fan design technology to spaceflight use. This paper will also discuss the potential benefits from this, which are significant, including 1) volume and mass savings from noise controls that are no longer as large or needed at all, 2) reduced system pressure loss from mufflers and silencers (that don’t need to be as restrictive) for better ventilation, 3) reduced power draw because of the reduced system pressure loss and the highly efficient fan design, and 4) satisfying spaceflight vehicle acoustic requirements to provide a safe and habitable acoustic environment for astronaut crewmembers. All of these benefits will be crucial for the successful development and operations of future spaceflight vehicles, space suits, and habitats.

Christopher S. Allen↗
NASA NTRS2010

High C/O Chemistry and Weak Thermal Inversion in the Extremely Irradiated Atmosphere of Exoplanet WASP-12b

The carbon-to-oxygen ratio (C/O) in a planet provides critical information about its primordial origins and subsequent evolution. A primordial C/O greater than 0.8 causes a carbide-dominated interior as opposed to the silicate-dominated composition as found on Earth; the solar C/O is 0.54. Theory, shows that high C/O leads to a diversity of carbon-rich planets that can have very different interiors and atmospheres from those in the solar system. Here we report the detection of C/O greater than or equal to 1 in a planetary atmosphere. The transiting hot Jupiter WASP-12b has a dayside atmosphere depleted in water vapour and enhanced in methane by over two orders of magnitude compared to a solar-abundance chemical equilibrium model at the expected temperatures. The observed concentrations of the prominent molecules CO, CH4, and H2O are consistent with theoretical expectations for an atmosphere with the observed C/O = 1. The C/O ratios are not known for giant planets in the solar system, although they are expected to equal the solar value. If high C/O ratios are common, then extrasolar planets are likely very different in interior composition, and formed very differently, from expectations based on solar composition, potentially explaining the large diversity in observed radii. We also find that the extremely irradiated atmosphere (greater than 2500 K) of WASP-12b lacks a prominent thermal inversion, or a stratosphere, and has very efficient day-night energy circulation. The absence of a strong thermal inversion is in stark contrast to theoretical predictions for the most highly irradiated hot-Jupiter atmospheres.

Madhusudhan, Nikku↗
NASA NTRS2017

Synoptic Traveling Weather Systems on Mars: Effects of Radiatively-Active Water Ice Clouds

Atmospheric aerosols on Mars are critical in determining the nature of its thermal structure, its large-scale circulation, and hence the overall climate of the planet. We conduct multi-annual simulations with the latest version of the NASA Ames Mars global climate model (GCM), gcm2.3+, that includes a modernized radiative-transfer package and complex water-ice cloud microphysics package which permit radiative effects and interactions of suspended atmospheric aerosols (e.g., water ice clouds, water vapor, dust, and mutual interactions) to influence the net diabatic heating. Results indicate that radiatively active water ice clouds profoundly affect the seasonal and annual mean climate. The mean thermal structure and balanced circulation patterns are strongly modified near the surface and aloft. Warming of the subtropical atmosphere at altitude and cooling of the high latitude atmosphere at low levels takes place, which increases the mean pole-to-equator temperature contrast (i.e., "baroclinicity"). With radiatively active water ice clouds (RAC) compared to radiatively inert water ice clouds (nonRAC), significant changes in the intensity of the mean state and forced stationary Rossby modes occur, both of which affect the vigor and intensity of traveling, synoptic period weather systems. Such weather systems not only act as key agents in the transport of heat and momentum beyond the extent of the Hadley circulation, but also the transport of trace species such as water vapor, water ice-clouds, dust and others. The northern hemisphere (NH) forced Rossby waves and resultant wave train are augmented in the RAC case: the modes are more intense and the wave train is shifted equatorward. Significant changes also occur within the subtropics and tropics. The Rossby wave train sets up, combined with the traveling synoptic period weather systems (i.e., cyclones and anticyclones), the geographic extent of storm zones (or storm tracks) within the NH. A variety of circulation features will be presented which indicate contrasts between the RAC and nonRAC cases, and which highlight key effects radiatively-active clouds have on physical and dynamical processes active in the current climate of Mars.

Atmospheric aerosols↗