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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 343 records · Page 19
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NASA NTRS2012

Mars Meteorolgical Network

Exploring and ultimately establishing a permanent presence on the surface of Mars will necessitate an understanding the weather conditions and the ability to forecast its dynamic behavior. The meteorology of Mars will need to be developed. This abstract puts forth a concept for a Mars Meteorological Network that will be used to investigate the Mars atmosphere behavior, explore the surface environment, and prepare for operational activities. It is proposed that the long term and the dynamic nature of the lower atmosphere and surface of Mars be observed with a distributed global array of simple automated surface nodes. The data would be ingested into the Mars Global Reference Atmospheric Model (Mars-GRAM) and other research tools for analyses to gain a better understanding of the atmospheric conditions on Mars.

Justh, H. L.↗
NASA NTRS1972

Problem of photochemical equilibrium of ozone in planetary atmospheres: Ozone distribution in the lower atmosphere of Mars

The inherent errors of applying terrestrial atmospheric ozone distribution studies to the atmosphere of other planets are discussed. Limitations associated with some of the earlier treatments of photochemical equilibrium distributions of ozone in planetary atmospheres are described. A technique having more universal application is presented. Ozone concentration profiles for the Martian atmosphere based on the results of the Mariner 4 radio occultation experiment and the more recent results with Mariner 6 and Mariner 7 have been calculated using this approach.

Grams, G. W.↗
NASA NTRS1977

Infrared heterodyne spectroscopy of CO2 in the atmosphere of Mars

An infrared heterodyne spectrometer with a resolving power of 6 million has been used to obtain detailed profiles of the 10-micron absorption lines of CO2 in the atmosphere of Mars. An analysis of the results with an empirical model-atmosphere calculation indicates a nearly pure CO2 atmosphere with an average surface pressure of 5.2 + or - 0.5 mbar in the observed regions, a subsolar surface temperature near 275 K, an atmospheric temperature of 235 to 240 K above the subsolar point, and a lapse rate of 2 K/km.

Betz, A. L.↗
NASA NTRS2001

One Martian Year of Atmospheric Observations by the Thermal Emission Spectrometer

The Mars Global Surveyor has completed one full Martian year of mapping. Infrared spectra returned by the Thermal Emission Spectrometer (TES) are very well suited for monitoring the thermal structure and the distribution of aerosols and water vapor in the Mars atmosphere. Nadir-viewing spectra allow a global picture of the state of the Mars atmosphere on a daily basis. We report here on the observed annual cycle of the latitudinal dependence of atmospheric temperature, dust aerosols, water-ice clouds, and water vapor.

Smith, Michael D.↗
NASA NTRS1987

The atmosphere of Mars and optical communications

The effects of the Martian atmosphere on an optical communication link are analyzed using Mariner 9, Viking Orbiter, and Viking Lander data. Clouds are found to have minimal effect because of their scarcity and thinness. Dust (from dust storms) has the dominant impact on opacity. However, periods of reduced visibility are infrequent and more closely resemble the effects of thin clouds on the earth. A simple argument is presented which suggests that the Martian atmosphere has fewer turbulence related effects (i.e., Mars has better resolution, lower image wander, and less scintillation) than the best of the earth's ground based locations.

Annis, J.↗
NASA NTRS2014

MAVEN Contamination Venting and Outgassing Analysis

Mars Atmosphere and Volatile EvolutioN (MAVEN) is the first mission to focus its study on the Mars upper atmosphere. MAVEN will study the evolution of the Mars atmosphere and climate, by examining the conduit through which the atmosphere has to pass as it is lost to the upper atmosphere. An analysis was performed for the MAVEN mission to address two distinct concerns. The first goal of the analysis was to perform an outgassing study to determine where species outgassed from spacecraft materials would redistribute to and how much of the released material might accumulate on sensitive surfaces. The second portion of the analysis serves to predict what effect, if any, Mars atmospheric gases trapped within the spacecraft could have on instrument measurements when re-released through vents. The re-release of atmospheric gases is of interest to this mission because vented gases from a higher pressure spacecraft interior could bias instrument measurements of the Mars atmosphere depending on the flow rates and directions.

Petro, Elaine M.↗
NASA NTRS1976

Flight characteristics of probes in the atmospheres of Mars, Venus, and the outer planets

Density, pressure, and temperature profiles of an unknown planetary atmosphere can be obtained from the high-speed entry of a probe provided the aerodynamic characteristics of the probe in this atmosphere are accurately known. An investigation of the effect of gas composition on probe aerodynamics has been conducted in the Ames Hypersonic Free Flight Facility by gun launching small-scale models into atmospheres representative of Mars, Venus, Jupiter, and Saturn. Aerodynamic data at conditions matching the velocity and Reynolds number at a number of points on the Viking trajectory (Mars) were obtained in both air and carbon dioxide and significant differences were noted. Aerodynamic data are also presented from tests in hydrogen and hydrogen-helium mixtures, gases which characterize the atmospheres of the outer planets.

Intrieri, P. F.↗
NASA NTRS1972

The atmosphere of Mars from Mariner 9 radio occultation measurements.

Mariner-9 S-band radio occultation measurements conducted during November and December 1971 are described in terms of new information that was obtained about the shape and atmosphere of Mars. The arrival of the spacecraft coincided with a severely obscuring global dust storm, and the effect of the dust in the atmosphere was reflected in the reduced temperature gradients that were measured in the daytime near-equatorial atmosphere, indicating (1) heating of the atmosphere by solar radiation absorbed by dust and (2) simultaneous cooling of the surface. In general, surface atmospheric pressures measured in the equatorial regions are in very good agreement with previous radio-occultation and earth-based measurements. A global disparity in pressures strongly suggests that the physical shape of Mars is more oblate than the shape of its gravitational equipotential surface.

Kliore, A. J.↗
NASA NTRS2018

The Dust in the Atmosphere of Mars and Its Impact on the Human Exploration of Mars: A NESC Workshop

The NASA Engineering and Safety Center (NESC) Chief Scientist provided support to produce an NESC final report on the "Dust in the Atmosphere of Mars and Its Impact on Human Exploration" workshop held June 1315, 2017, in Houston, TX. This report follows the standard NESC report format to describe the findings, observations, and NESC recommendations developed by the workshop participants. The key stakeholders for the final report are the Mars mission designers and engineers for the precursor missions and the crewed mission, and the NESC. Further stakeholders are the mission planners deciding on the payload selections for the Mars missions.

Winterhalter, Daniel↗
NASA NTRS1999

Mars Characterization for Future Missions

Annual simulations of Mars' atmosphere made with the NASA Ames Mars General Circulation Model have been used to extract and generate products to provide statistical products that detail the variability of Mars' atmosphere on fairly short time scales. These products are needed for the creation of a new version of Mars-GRAM, due for completion in June, 1999. The updated Mars-Gram, in turn, will provide guidance for forthcoming aerobraking and aerocapture activities. We have created files containing zonally-averaged fields (temperatures, densities, pressures, and winds, all on z-surfaces), as well as zonally-averaged diurnal and semidiurnal tidal amplitudes and phases. All fields represent a time averaged state (over either 5 or 30 sols), and all fields are available at each of 12 seasons for a Mars year (the seasons being 30deg of Ls apart). Files for low and moderate dust loading cases are liable via anonymous ftp. Files for a high dust case will be in place shortly.

Bridger, Alison F. C.↗
NASA NTRS2014

Mars Entry Atmospheric Data System Modeling, Calibration, and Error Analysis

The Mars Science Laboratory (MSL) Entry, Descent, and Landing Instrumentation (MEDLI)/Mars Entry Atmospheric Data System (MEADS) project installed seven pressure ports through the MSL Phenolic Impregnated Carbon Ablator (PICA) heatshield to measure heatshield surface pressures during entry. These measured surface pressures are used to generate estimates of atmospheric quantities based on modeled surface pressure distributions. In particular, the quantities to be estimated from the MEADS pressure measurements include the dynamic pressure, angle of attack, and angle of sideslip. This report describes the calibration of the pressure transducers utilized to reconstruct the atmospheric data and associated uncertainty models, pressure modeling and uncertainty analysis, and system performance results. The results indicate that the MEADS pressure measurement system hardware meets the project requirements.

Karlgaard, Christopher D.↗
NASA NTRS1998

Mars Pathfinder Atmospheric Entry Reconstruction

The primary objective of the Mars Pathfinder mission was to demonstrate an innovative, low-cost and reliable method for placing a science payload on the surface of Mars. This paper describes the results of an effort to access the spacecraft performance during Entry, Descent and Landing.

Mars↗
NASA NTRS1992

Mapping Mars water vapor with the Very Large Array

This paper presents the first radio measurements of Mars atmospheric water, retrieved from interferometric spectral line observations with the NRAO VLA. Large atmospheric path lengths on the limb of Mars lead to an annulus of H2O line emission which provides a measure of the diurnal and latitudinal variability of atmospheric water on Mars. The measured line shapes of the observed H2O emission yield the first direct measurements of the vertical mixing profile of H2O in the Mars atmosphere. The observations indicate a very dry Mars atmosphere in which the globally averaged water column is approximately 3 pr micron.

Clancy, R. T.↗
NASA NTRS2000

The Coupled Roles of Dust and Clouds in the Mars Climate

During the period October 1997 to September 1999 we obtained and analyzed over 100 millimeter-wave observations of Mars atmospheric CO line absorption for atmospheric temperature profiles. These measurements extend through one full Mars year (solar longitudes L(sub S) of 190 deg in 1997 to 180 deg in 1999) and coincide with atmospheric temperature profile and dust column measurements front the Thermal Emission Spectrometer (TES) experiment on board the Mars Global Surveyor (MGS) spacecraft. A comparison of Mars atmospheric temperatures retrieved by these distinct methods provides the first opportunity to place the long-term (1982-1999) millimeter retrievals of Mars atmospheric temperatures within the context of contemporaneous, spatially mapped spacecraft, observations. Profile comparisons of 0-30 km altitude atmospheric temperatures retrieved with the two techniques agree typically to within the 5 K calibration accuracy of the millimeter observations. At the 0.5 mbar pressure level (approximately 25 km altitude) the 30N/30S average for TES infrared temperatures and the disk-averaged millimeter temperatures are also well correlated in their seasonal and dust-storm-related variations over the 1997-1999 period. This period includes the Noachis Terra regional dust storm, which led to very abrupt heating (approximately 15 K at 0.5 mbar) of the global Mars atmosphere at L(sub S)=224 deg in 1997 [Christensen et al., 1998; Conrath et al., this issue; Smith et al., this issue]. Much colder (10-20 K) global atmospheric temperatures were observed during the 1997 versus 1977 perihelion periods (L(sub S)=200 deg-330 deg), consistent with the much (2 to 8 times) lower global dust loading of the atmosphere during the 1997 perihelion dust storm season versus the Viking period of the 1977a,b storms. The 1998-1999 Mars atmosphere revealed by both the millimeter and TES observations is also 10-15 K colder than presented by the Viking climatology during the aphelion season (L(sub S)=0 deg-180 deg, northern spring/summer) of Mars. We reassess the observational basis of the Viking dusty-warm climatology for this season to conclude that the global aphelion atmosphere of Mars is colder, less dusty, and cloudier than indicated by the established Viking climatology even for the Viking period. We also conclude that Mars atmospheric temperatures exhibit their most significant interannual variations during the perihelion dust storm season (10-20 K for L(sub S)=200 deg-340 deg) and during the post-aphelion northern summer season (5-10 K for L(sub S)=100 deg-200 deg).

Clancy, R. Todd↗
NASA NTRS2020

Design of a Direct-Detection Wind and Aerosol Lidar for Mars Orbit

The present knowledge of the Mars atmosphere is greatly limited by a lack of global measurements of winds and aerosols. Hence, measurements of height-resolved wind and aerosol profiles are a priority for new Mars orbiting missions. We have designed a direct-detection lidar (MARLI) to provide global measurements of dust, winds and water ice profiles from Mars orbit. From a 400-km polar orbit, the instrument is designed to provide wind and backscatter measurements with a vertical resolution of 2 km and with resolution of 2° in latitude along track. The instrument uses a single-frequency, seeded Nd:YAG laser that emits 4 mJ pulses at 1064 nm at a 250 Hz pulse rate. The receiver utilizes a 50-cm diameter telescope and a double edge Fabry-Pérot etalon as a frequency discriminator to measure the Doppler shift of the aerosol-backscatter profiles. The receiver also includes a polarization-sensitive channel to detect the cross-polarized backscatter profiles from water ice. The receiver uses a sensitive 4 × 4 pixel HgCdTe avalanche photodiode array as a detector for all signals. Here we describe the measurement concept, instrument design, and calculate its performance for several cases of Mars atmospheric conditions. The calculations show that under a range of atmospheric conditions MARLI is capable of measuring wind speed profiles with random error of 2–4 m/s within the first three scale heights, enabling vertically resolved mapping of transport processes in this important region of the atmosphere.

Cremons, Daniel R.↗
NASA NTRS2010

Why Haven't Mars Rovers Landed Where They Were Expected to?

In a recent study (Desai, 2008) of the actual landing sites for the Mars Pathfinder, Mars Exploration Rovers and the Phoenix Mars Lander, data collected indicates that these missions landed at least 13 km downrange of their targeted landing sites. A direct reason is that density measurements taken during entry, descent and landing were consistently found to be lower than those predicted by Mars atmospheric models. The basis of this study is to further investigate this problem to see if certain aspects of current Mars atmospheric models need to be reevaluated. This study compared four different atmospheric profiles at nine pairs of comparable sites around Mars. The comparable sites are similar in location and Local True Solar Time; however they are from different Mars years. One year had normal conditions, while the other year experienced a global dust storm. Three of the atmospheric profiles were obtained by the Mars Global Surveyor (MGS); these data sets include a Radio Science profile and Thermal Emission Spectrometer data in limb and nadir projections. The three MGS data sets were selected from large observational databases to allow the sites to have data observed at nearcoincident times. The last atmospheric profile is from the Mars Global Reference Atmospheric Model (Mars-GRAM), an engineering level atmospheric model widely used for mission applications. Through careful data evaluation, several conclusions were drawn. Ratios among the data show that the three observed MGS profiles were consistent with each other, although they were recorded by three different methods. Mars-GRAM data had larger differences from the observed data. Mars-GRAM particularly had issues with consistently overestimating upper atmosphere atmospheric density, as noted in Desai s study. Differences between the observed atmospheric density profiles from the Mars-GRAM atmospheric density profile could be attributed to a temperature bias in the model, especially in the upper atmosphere.

Badger, Andrew M.↗