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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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Several of NASA's future Planetary Exploration (specifically Mars) missions will require rechargeable batteries of high specific energy and energy density and more importantly of good low temperature performance.
The zonal mean eddy heat flux is directly proportional to the wave activity that propagates from the troposphere into the stratosphere. This quantity is a simple eddy diagnostic which is easily calculated from conventional meteorological analyses. Because this "wave driving" of the stratosphere has a strong impact on the stratospheric temperature, it is necessary to compare the impact of the flux with respect to stratospheric radiative changes caused by greenhouse gas changes. Hence, we must understand the precision and accuracy of the heat flux derived from our global meteorological analyses. Herein, we quantify the stratospheric heat flux using five different meteorological analyses, and show that there are 30% differences between these analyses during the disturbed conditions of the northern hemisphere winter. Such large differences result from the planetary differences in the stationary temperature and meridional wind fields. In contrast, planetary transient waves show excellent agreement amongst these five analyses, and this transient heat flux appears to have a long term downward trend.
The earliest atmospheres of the terrestrial planets are thought to have been hotter, have stronger winds and rotate faster than atmospheres of today. Since these primitive atmospheres were weakly bound, they evolved rapidly because atmospheric escape was very strong, often referred to as "blowoff." Such escape has been treated as hydrodynamic, transonic flow; similar to solar wind flow dynamics. However, in many cases, although the outward flow is hydrodynamic at low altitudes, it becomes collisionless at higher altitudes, before sonic speeds are ever attained. Recent models dealing with the transition from fluid to kinetic flow have applied the Jeans escape flux at the exobase. This approach leads to escape rates that are too low, because thermospheric winds and planetary rotation are known to increase the escape flux above the corresponding Jeans flux. In particular, for a given density and temperature at the exobase, the escape flux increases as the wind speed and/or the rotation rate increase. Also, for a given wind speed and rotation rate, the escape flux enhancement over the Jeans flux increases as the mass of an escaping constituent increases, an important factor in isotope fractionation, especially the enrichment of deuterium on Mars. Accounting for a range of possible temperatures, thermospheric wind speeds and planetary rotation rates in the primitive atmospheres of the terrestrial planets, estimates are made of light constituent escape flux increases over the corresponding Jeans fluxes.
This final report from the University of Wisconsin-Madison Cooperative Institute for Meteorological Satellite Studies (CIMSS) summarizes a research program designed to improve our knowledge of the water and energy balance of the land surface through the application of remote sensing and in-situ data sources. The remote sensing data source investigations to be detailed involve surface radiometric ('skin') temperatures and also high-spectral-resolution infrared radiance data from atmospheric sounding instruments projected to be available at the end of the decade, which have shown promising results for evaluating the land-surface water and energy budget. The in-situ data types to be discussed are measurements of the temporal changes of the height of the planetary boundary layer and measurements of air temperature within the planetary boundary layer. Physical models of the land surface, planetary boundary layer and free atmosphere have been used as important tools to interpret the in-situ and remote sensing signals of the surface energy balance. A prototype 'optimal' system for combining multiple data sources into a three-dimensional estimate of the surface energy balance was developed and first results from this system will be detailed. Potential new sources of data for this system and suggested continuation research will also be discussed.
Anharmonic models are used to describe the high temperatures and the electronic effects characteristic of shock wave phenomena and planetary interiors. It is found that a generalized Grueneisen function dependent on temperature and volume is necessary for the self-consistent application of the Mie-Grueneisen equation at the physical conditions encountered in shock wave phenomena or in the interior of planets. It is noted that at temperatures of a few thousand degrees Kelvin, by deriving the function in terms of anharmonic lattice dynamics, the difference between gamma and gamma(th) is of the same order of a magnitude as gamma. This leads to the conclusions that (1) gamma is not a function of temperature and (2) gamma?gamma(th) does not explain either the equation of state of planetary interiors or high-temperature shock wave phenomena.
Attention is given to some of the major unresolved issues concerned with the physics of planetary interiors. The important advances in observations, and experimental and theoretical investigations are briefly reviewed, and some areas for further study are identified, including: the characteristics of atomic and electronic degrees of freedom at the high pressures and temperatures typical of a condensed planetary core; the behavior of water at megabar pressures; and the nature of the core-alloy in the earth and in the core mantle phase boundary. Consideration is also given to the behavior of carbon at high pressures and temperatures in the presence of oxygen and hydrogen; the behavior of the volatile ice assemblage in Titan at pressures of 2-40 kbar; and the electrical conductivities of matter under planetary core conditions.
The origin of planetary atmospheres is thought to be the result of bombardment of a growing planet by massive planetesimals. According to some models, the accumulation of released water vapor and/or carbon dioxide can result in the formation of a dense and hot primordial atmosphere. Among source and sink processes of atmospheric water vapor the formation of hydroxides was considered mainly as rehydration of dehydrated minerals (foresterite and enstatite). From our point of view, the formation of hydroxides is not limited to rehydration. Condensation of small silicate particles in a spreading vapor cloud and their interaction with a wet atmosphere can also result in the origin of hydrated phases which have no genetic connections with initial water bearing minerals. We present results of two experiments of a simulated interaction of condensed silicate matter which originated during vaporization of dry clinopyroxene in a wet helium atmosphere.
It is pointed out that transition metal ions in silicate minerals, glasses, and crystalline and amorphous oxyhydroxides and salts contribute to the visible-near infrared spectral profiles of planetary surfaces. Investigations are conducted to obtain spectral information which might be helpful in the interpretation of the remote-sensed spectra of planetary surfaces. A description is presented of the results of high temperature crystal field spectral measurements of a variety of heated minerals containing Cr(3+), Fe(3+), Fe(++), and Mn(++) ions in different coordination symmetries, taking into account a correlation of the temperature-induced variations with those previously observed for octahedrally coordinated Fe(++)-bearing silicates. The employed experimental methods are also discussed, giving attention to the preparation of the samples, the determination of the absorption spectra, electron microprobe analyses, and the curve fitting procedure.
Research is reported on the effects of increasing the CO2, aerosols, and water content of the atmosphere on the surface temperature and climatology. An atmospheric model is described with the incoming solar radiation for a planetary albedo of 33 percent, surface temperature of 288 K, relative humidity of 75 percent, cloud cover of 48 percent, CO2 of 0.3 parts per thousand, and aerosol density of two million per square centimeter. The results show that if the CO2 increases by a factor of 1000 or more, the total pressure of the atmosphere increases, and the earth may become as hot as Venus. It is also shown that as the amount of dust particles in the atmosphere increases, the solar radiation decreases, and the surface temperature lowers.
Inversion techniques are applied to the few earth based observations of the Jovian emission spectrum to obtain directly the profiles of atmospheric temperature and ammonia abundance. The temperature profile is characterized by a definite tropopause region with a temperature of about 115K and a stratospheric region in which the temperature slowly increases with altitude. The derived ammonia profile indicates the presence of a saturated ammonia layer with a base temperature of approximately 14OK. The concept is described deducing the temperature and constituent profile of a planetary atmosphere from orbiter measurements of the planet's IR limb radiance profile. Analysis of the weighting functions for the Martian atmosphere indicates that a limb radiance profile in the 15 micron CO2 band can be used to determine the Martian atmospheric temperature profile from 20 to 60 km.
Ceramic column grid array (CCGA) packages have been increasing in use based on their advantages of high interconnect density, very good thermal and electrical performance, and compatibility with standard surface-mount packaging assembly processes. CCGA packages are used in space applications such as in logics and microprocessor functions, telecommunications, flight avionics, and payload electronics. As these packages tend to have less solder joint strain relief than leaded packages, the reliability of CCGA packages is very important for short- and long-term space missions. Certain planetary satellites require operations of thermally uncontrolled hardware under extremely cold and hot temperatures with large diurnal temperature change from day to night. The planetary protection requires the hardware to be baked at +125 C for 72 hours to kill microbugs to avoid any biological contamination, especially for sample return missions. Therefore, the present CCGA package reliability research study has encompassed the temperature range of 185 to +125 C to cover various NASA deep space missions. Advanced 1152 and 1272 CCGA packaging interconnects technology test hardware objects have been subjected to ex treme temperature thermal cycles from 185 to +125 C. X-ray inspections of CCGA packages have been made before thermal cycling. No anomalous behavior and process problems were observed in the x-ray images. The change in resistance of the daisy-chained CCGA interconnects was measured as a function of increasing number of thermal cycles. Electrical continuity measurements of daisy chains have shown no anomalies, even until 596 thermal cycles. Optical inspections of hardware have shown a significant fatigue for CCGA 1152 packages over CCGA 1272 packages. No catastrophic failures have been observed yet in the results. Process qualification and assembly are required to optimize the CCGA assembly processes. Optical inspections of CCGA boards have been made after 258 and 596 thermal cycles. Corner columns have started showing significant fatigue per optical inspection results.
The main objective of the proposal was to model the collision induced, second overtone band of gaseous hydrogen at low temperatures. The aim of this work is to assist planetary scientists in their investigation of planetary atmospheres, mainly those of Uranus and Neptune. The recently completed extended database of collision induced dipole moments of hydrogen pairs allowed us, for the first time, to obtain dipole moment matrix elements responsible for the roto-vibrational collision induced absorption spectra of H2-H2 in the second overtone band. Despite our numerous attempts to publish those data, the enormous volume of the database did not allow us to do this. Instead, we deposited the data on a www site. The final part of this work has been partially supported by NASA, Division for Planetary Atmospheres. In order to use our new data for modelling purpose, we first needed to test how well we can reproduce the existing experimental data from theory, when using our new input data. Two papers resulted from this work. The obtained agreement between theoretical results and the measurements appeared to be within 10-30%. The obviously poorer agreement than observed for the first H2 overtone, the fundamental, and the rototranslational bands can be attributed to the fact that dipole moments responsible for the second overtone are much weaker, therefore susceptible to larger numerical uncertainties. At the same time, the intensity of the second overtone band is much weaker and therefore it is much harder to be measured accurately in the laboratory. We need to point out that until now, no dependable model of the 2nd overtone band was available for modelling of the planetary atmospheres. The only one, often referred to in previous works on Uranian and Neptune's atmospheres, uses only one lineshape, with one (or two) parameter(s) deduced at the effective temperature of Uranus (by fitting the planetary observation). After that, the parameter(s) was(were) made temperature dependent according to some very simple relation. Summarizing, no reliable temperature-dependent model has been available yet. Our approach was a bit different from similar attempts done earlier, on account of the poorer agreement of theory with experiment. We needed to resort to some semi-empirical procedure. While we were in a favourable position to be able to rely on the physical input data, these, apparently, did not supply the most dependable predictions (simply because the results did not agree well enough with experimental data). On the other hand, the relative deviations between the theory and experiment were comparable at 77 and at 298 K. That fact indicated that theory is capable of predicting the temperature dependence of the absorption spectra well. We have thus chosen the "middle way". We have fitted the existing measurements with many 3- parameter lineshapes, in order to achieve the closest fit.
The temperature rise and enhanced winds during an upper atmospheric warming cause substantial changes in the high level ozone profile of the sunlit winter hemisphere. Calculations based on a photochemical model, using temperatures measured at Fort Churchill during a major warming, predict a factor of 2 variation in the ozone number density near 60 km over a time period of approximately 3 weeks. This temporal variability at a fixed location results from the planetary wave structure of the temperature field and reflects a similar longitudinal behavior at a given time. The ozone number density at fixed altitude is a maximum when the temperature is greatest at and below this level. This is due primarily to thermal expansion of the atmosphere which results in a large increase in pressure at constant altitude. However, chemical activity during a warming decreases the mesospheric ozone mixing ratio at fixed pressure. The ozone mixing ratio at constant pressure during the peak of the event studied is near 75% of its unperturbed value. The predicted variability of ozone in longitude and time demonstrates the need for hemispheric scale information on trace gas abundances, temperature, and winds in order to delineate adequately the response of upper atmospheric composition to a major perturbation.
Planetary probe conical scanning system, signal processing, S-band power amplifier survey, modulation and bit synchronization, antenna temperature, and trajectory perturbations
Silicon-On-Insulator (SOI) technology utilizes the addition of an insulation layer in its structure to reduce leakage currents and to minimize parasitic junctions. As a result, SOIbased devices exhibit reduced internal heating as compared to the conventional silicon devices, consume less power, and can withstand higher operating temperatures. In addition, SOI electronic integrated circuits display good tolerance to radiation by virtue of introducing barriers or lengthening the path for penetrating particles and/or providing a region for trapping incident ionization. The benefits of these parts make them suitable for use in deep space and planetary exploration missions where extreme temperatures and radiation are encountered. Although designed for high temperatures, very little data exist on the operation of SOI devices and circuits at cryogenic temperatures. In this work, the performance of a commercial-off-the-shelf (COTS) SOI half-bridge driver integrated circuit was evaluated under extreme temperatures and thermal cycling. The investigations were carried out to establish a baseline on the functionality and to determine suitability of this device for use in space exploration missions under extreme temperature conditions.
The Timed Doppler Interferometer (TIDI) will accurately and precisely determine the global vector MLTI (Mesosphere and Lower Thermosphere) wind, temperature, and density profiles. It will measure characteristics of the gravity wave and planetary wave spectra. The tidal characteristics of temperature, density, and wind in the MLTI will be determined. The neutral and ion winds will be measured to characterize the electrodynamical behavior of the MLTI. Oxygen and O2 abundances and nocticulent cloud activity will be measured. This review goes into the calibration and error sources, optical design, mechanisms design, detector design, electronics design, microprocessor and flight software design, and quality assurance and parts.
Spacescience instruments with cooled detectors require innovative thermal cooling solutions to meet science objectives. Detector sensitivity increases with decreasing temperature and low optics temperatures are often needed to reduce background photon noise. As the detector spectral range coverage increases from the visible to far infrared also requires lower detector temperatures. Increasing demands on detector performance lead to larger format detectors and higher refresh rates resulting in significant increases in power dissipation. Passive coolers rely on emissive power of radiating surfaces to reject heat to space. As the operating temperature requirements of detectors and optics decreases, the ability to reject heat to space becomes increasingly more difficult. Reducing both cooler internal parasitic and external environmental heat loads and maximizing the passive cooler field of view to space will enhance performance. While instrument heat loads and passive cooler parasitic heat loads are controlled by instrument designers, the external environmental heat loads and cooler views to space are governed by spacecraft and mission designers. Solar powered planetary missions require large arrays to generate sufficient power for spacecraft subsystems and payloads. Two or more solar array wings with cell coverage of the order of 40-80 m2 are often needed to generate sufficient power at 3-6 AU. These large arrays are typically symmetrically configured and can extend tens of meters. The arrays along with spacecraft attitude requirements near the target planetary bodies pose significant challenges for passive cooling at large AU. It is very difficult to provide a clear field of view to space for the cooler with large articulating arrays while keeping solar loads from impinging the cooler and meeting the spacecraft attitude science pointing requirements. This is counter intuitive because of the decreasing solar flux and colder planetary body temperatures at large AU. This paper presents the challenges and opportunities of passive cryogenic cooling versus active cooling for solar powered planetary missions.