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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 NTRS1976

Diurnal tide in the Martian atmosphere

Classical atmospheric tidal theory is extended to include the effects of large-amplitude planetary-scale variations of the terrain height. Utilizing simple models of the thermotidal forcing, the resulting technique is used to compute the diurnal tide in both the dust-free and the dust-laden Martian atmosphere. The main effect of the Martian variable terrain is to drive topographic tidal modes which can propagate vertically and to excite the possibly resonant diurnal Kelvin mode. The resulting surface wind can exceed 20 m/sec and may determine the preferred location for the initiation of global dust storms. In the middle Martian atmosphere (30-80 km) static and shear instabilities embedded within the tidal fields will generate extensive, though variable, regions of turbulence. Vertical mixing by this turbulence and transport by the tide itself may help to stabilize the middle Martian atmosphere against photolysis.

Zurek, R. W.↗
NASA NTRS1992

Aeronomy of the current Martian atmosphere

The thermal structure of the Martian atmosphere, which varies diurnally, seasonally and episodically, is discussed. The atomic oxygen airglow at 1304 A is used to determine the density of atomic oxygen, and the 1216-A Lyman-alpha line is used to calculate the density of atomic hydrogen and, when coupled with the temperature measurement, the escape flux of atomic hydrogen. The most intense airglow is the IR atmospheric band of O2 at 1.27 micron that results from the photodissociation of ozone. The escape mechanism for atomic hydrogen is thermal, or Jeans, escape, while the atomic oxygen escape is caused by a nonthermal process, namely, the dissociative recombination of O2(+). The ratio of deuterium to hydrogen is enriched by a factor of 6. Three-dimensional models of the Mars thermospheric circulation show that planetary rotation has a significant effect on the wind, composition, and temperature structure.

Barth, C. A.↗
NASA NTRS1993

Eddy transport of water vapor in the Martian atmosphere

Viking orbiter measurements of the Martian atmosphere suggest that the residual north polar water-ice cap is the primary source of atmospheric water vapor, which appears at successively lower northern latitudes as the summer season progresses. Zonally symmetric studies of water vapor transport indicate that the zonal mean meridional circulation is incapable of transporting from north polar regions to low latitudes the quantity of water vapor observed. This result has been interpreted as implying the presence of nonpolar sources of water. Another possibility is the ability of atmospheric wave motions, which are not accounted for in a zonally symmetric framework, to efficiently accomplish the transport from a north polar source to the entirety of the Northern Hemisphere. The ability or inability of the full range of atmospheric motions to accomplish this transport has important implications regarding the questions of water sources and sinks on Mars: if the full spectrum of atmospheric motions proves to be incapable of accomplishing the transport, it strengthens arguments in favor of additional water sources. Preliminary results from a three dimensional atmospheric dynamical/water vapor transport numerical model are presented. The model accounts for the physics of a subliming water-ice cap, but does not yet incorporate recondensation of this sublimed water. Transport of vapor away from this water-ice cap in this three dimensional framework is compared with previously obtained zonally symmetric (two dimensional) results to quantify effects of water vapor transport by atmospheric eddies.

Murphy, J. R.↗
NASA NTRS1993

Tentative identification of formaldehyde in the Martian atmosphere

Solar occultation observations of the Martian atmosphere near the limb of the planet were performed during the Phobos mission by means of the Auguste infrared spectrometer in the ranges 2707-2740 and 5392-5272/cm with a resolving power of approximately = 1300. The spectra exhibit features at 2710 and 2730/cm which have not been identified previously. After applying a set of corrections to the data and examining the spectra of various molecules, we are led to conclude that the best candidate for the above-mentioned features is formaldehyde (CH2O). It was observed in eight of the nine successful occultation sequences, mainly between 8 and 20 km with an average mixing ratio of 0.5 (+0.8, - 0.3) ppm (there are no good data below 8 km). The observations are performed in equatorial spring conditions. The altitude distribution of formaldehyde reveals correlation with the permanent haze opacity.

Korablev, O. I.↗
NASA NTRS1993

Groundbased monitoring of Martian atmospheric opacity

The amount of dust in the Martian atmosphere is variable in both space and time. The presence of aerosols in the Mars atmosphere complicates quantitative analysis of Martian surface properties. We have developed a model for Mars surface and atmospheric scattering based on equations in Hillier et al (1991). This formulation was chosen for its speed of computation and because it accounts for the spherical geometry of atmospheric scattering at high mission angles, i.e., near the planetary limb.

Herkenhoff, K. E.↗
NASA NTRS2001

Carbon Dioxide Clouds at High Altitude in the Tropics and in an Early Dense Martian Atmosphere

We use a time dependent, microphysical cloud model to study the formation of carbon dioxide clouds in the Martian atmosphere. Laboratory studies by Glandor et al. show that high critical supersaturations are required for cloud particle nucleation and that surface kinetic growth is not limited. These conditions, which are similar to those for cirrus clouds on Earth, lead to the formation of carbon dioxide ice particles with radii greater than 500 micrometers and concentrations of less than 0.1 cm(exp -3) for typical atmospheric conditions. Within the current Martian atmosphere, CO2 cloud formation is possible at the poles during winter and at high altitudes in the tropics during periods of increased atmospheric dust loading. In both cases, temperature perturbations of several degrees below the CO2 saturation temperature are required to nucleate new cloud particles suggesting that dynamical processes are the most common initiators of carbon dioxide clouds rather than diabatic cooling. The microphysical cloud model, coupled to a two-stream radiative transfer model, is used to reexamine the impact of CO2 clouds on the surface temperature within a dense CO2 atmosphere. The formation of carbon dioxide clouds leads to a warmer surface than what would be expected for clear sky conditions. The amount of warming is sensitive to the presence of dust and water vapor in the atmosphere, both of which act to dampen cloud effects. The radiative warming associated with cloud formation, as well as latent heating, work to dissipate the clouds when present. Thus, clouds never last for periods much longer than several days, limiting their overall effectiveness for warming the surface. The time average cloud optical depth is approximately unity leading to a 5-10 K warming, depending on the surface pressure. However, the surface temperature does not rise about the freezing point of liquid water even for pressures as high as 5 bars, at a solar luminosity of 75% the current value.

Colaprete, Anthony↗
NASA NTRS2011

Development of an Electrostatic Precipitator to Remove Martian Atmospheric Dust from ISRU Gas Intakes During Planetary Exploration Missions

Manned exploration missions to Mars will need dependable in situ resource utilization (ISRU) for the production of oxygen and other commodities. One of these resources is the Martian atmosphere itself, which is composed of carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%), oxygen (0.13%), carbon monoxide (0.07%), and water vapor (0.03%), as well as other trace gases. However, the Martian atmosphere also contains relatively large amounts of dust, uploaded by frequent dust devils and high Winds. To make this gas usable for oxygen extraction in specialized chambers requires the removal of most of the dust. An electrostatic precipitator (ESP) system is an obvious choice. But with an atmospheric pressure just one-hundredth of Earth's, electrical breakdown at low voltages makes the implementation of the electrostatic precipitator technology very challenging. Ion mobility, drag forces, dust particle charging, and migration velocity are also affected because the low gas pressure results in molecular mean free paths that are approximately one hundred times longer than those at Earth .atmospheric pressure. We report here on our efforts to develop this technology at the Kennedy Space Center, using gases with approximately the same composition as the Martian atmosphere in a vacuum chamber at 9 mbars, the atmospheric pressure on Mars. We also present I-V curves and large particle charging data for various versions of wire-cylinder and rod-cylinder geometry ESPs. Preliminary results suggest that use of an ESP for dust collection on Mars may be feasible, but further testing with Martian dust simulant is required.

Clements, J. Sidney↗
NASA NTRS1994

Durability of Carbon-Carbon Composites to a Simulated Martian Atmosphere

A new facility was designed and constructed to investigate the effects of the Martian atmosphere on high temperature radiator components. Preliminary experimental results from carbon-carbon composite radiator samples suggest that carbon is unstable in the simulated Martian atmosphere at a temperature of 600 C, consistent with previous thermodynamic modeling. However, more work is needed to identify the exact mechanism. The versatile design of the facility permits additional study of materials stability in the presence of other atmospheres.

Jaworske, D. A.↗
NASA NTRSDate not supplied

Scroll Pump Dust Tolerance Test for Martian Atmospheric Acquisition

The ability to generate oxygen on the Martian surface will be essential to establishing a human presence on Mars. Flow generating devices such as pumps, compressors, and blowers will be crucial components in Martian atmospheric acquisition and processing systems that need to work reliably during the mission duration. A concern with the reliability of the system is its ability to continue to perform nominally when Martian dust, if it bypasses the inlet filter, enters into the system. A series of tests were conducted to simulate the ingestion of Martian dust on a small scroll pump, similar to the one used on the MOXIE payload. The inlet of the pump was connected to a large volume closed-loop pipe system, known as the Mars Atmospheric Flow Loop, containing pure CO2 gas at a Martian pressure of 7 Torr. A length of stainless steel tubing was extended from the inlet port of scroll pump, which was mounted outside the flow loop, to the inside volume of the flow loop using a feed-through compression fitting. A steady low-speed flow was generated inside the flow loop to continuously disperse and transport the dust toward the inlet tubing. JSC-Mars 1 Martian simulant was used to challenge the pump. Pump performance parameters such as flow rate, pump speed, pressure and temperature were monitored during these tests. Samples of the dust entering the pump inlet were taken prior to the exposure tests, using an inline filter element to determine the rate of dust ingestion into the internal components of the pump. After two tests with exposure times of one hour, the data indicated that small changes in pump performance took place under high rates of dust exposure.

Martian Atmospheric↗
NASA NTRS1992

Implications of isotopic compositions of N and Ne in the Martian atmosphere to temporal evolution of its atmosphere and regolith

The isotopic compositions of N and Ne in the Martian atmosphere are governed by several factors, principal among which are the temporal evolution in (1) the absolute surface pressure of oxygen, (2) the physicochemical characteristics of the regolith, and finally (3) the N-15 enrichment expected due to preferential hydrodynamical escape of N-14 (due to solar wind bombardment). Each of these factors is unique to Mars. In fact, no other planet offers the uniquely favorable situations for N-15 and Ne-21 enrichments. The cosmogenic production of N-15 is, in particular, unique. It promises to provide very valuable constraints on the temporal evolution of the martian CO2 and H2O, both in the atmosphere and regolith. The rate of production of cosmogenic (spallation) N-15 is dependent on the surface pressure of oxygen, the principal target element for formation of N-15. In view of the relatively high O/N ratio in the martian atmosphere, relatively high N-15/N ratio are expected to arise from cosmogenic reactions. The added bonus comes from the fact that an appreciable production of N-15 is expected in the martian regolith because of its thin atmosphere. From model calculations it is shown that if accurate isotopic composition data become available for N and Ne, it should be possible to put robust constraints on the time averages martian oxygen surface pressure and subsurface water in the upper layers.

Lal, D.↗
NASA NTRS1963

Planetary Aeronomy: NO2 In the Martian Atmosphere - 2

The transmission curve of the Martian atmosphere derived by Opik is compared with transmission curves of an atmosphere containing various amounts of nitrogen dioxide. It is found that the amount of 6 x l0(exp 18) sq cm column NO2 (or even less) given by Sinton as an upper limit for the Martian NO2 content could adequately explain the phenomenon of the blue haze. This finding made it worthwhile to investigate the effect of the temperature and pressure sensitive equilibrium 2 NO2 reversibly yields N204 upon the total NO2 content and the altitude-number density distributions of NO2 and N204. Computations were carried out for surface temperatures of 273 K, 243 K, 213 K, and 183 K and for three different temperature distributions. The discussion of the results leads to the suggestion of several important new experiments.

Warneck, P.↗