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NASA NTRS2020

Lunar Dust Simulant Particle Adhesion on Copolyimide Alkyl Ethers

Mitigation of lunar dust contamination is one of the greatest challenges to be overcome to realize a sustained lunar presence. Likely solutions will integrate active mitigation strategies, requiring the input of external energy, and passive materials, exhibiting an intrinsic resistance to lunar dust adhesion. In this work, a series of copolyimide alkyl ethers containing per fluorinated side-chains were generated to evaluate the influence surface modification agents have on surface chemical, topographical, and mechanical properties. An expanded testing protocol to characterize the adhesion interaction between lunar dust simulant and the copolyimide substrate was carried out. The interfacial adhesion strength was in-situ measured by a custom-built particulate adhesion instrument, utilizing a sonic wand. Surface mechanical properties were characterized by nanoindentation, utilizing the continuous stiffness measurement approach. A nominal presence of surface modifying agents, 1 wt%, resulted in a six-fold reduction in adhesion strength of the interface. A strong inverse correlation between the adhesion strength and Young’s modulus of the substrate was identified. The reduction was attributed to a synergistic interaction between the surface energy, surface roughness, and modulus of the copolyimide alkyl ethers film.

Lunar Dust, Particulate Adhesion, Surface Migratio↗
NASA NTRS1979

Martian wind activity detected by a seismometer at Viking lander 2 site

Since the Viking lander 2 seismometer (Anderson et al., 1977) located on top of the lander is extremely sensitive to Martian winds, it can provide a record of Martian wind activity. The seismograph continuously samples the wind-induced lander vibration, and its output complements meteorological data. Some pertinent seismic data are presented along with results of a preliminary spectral analysis of the data. Attention is given to wind speed/seismic noise correlation, and to long-term variation and periodicity. The results indicate that wind variations on Mars are very regular in the summer and winter seasons. Winds are light in summer and exhibit a strong diurnal periodicity, the strongest winds occurring in the early afternoon. Winds become stronger and more irregular in autumn. In all seasons nighttime conditions are usually very quiet. The high wind season correlates with the global dust storm duration. Spring is characterized by very strong though variable wind activity. Other details are also presented.

Nakamura, Y.↗
NASA NTRS1988

Irradiation records in meteorites

The approximately 4.6 billion-year history of a meteorite will encompass at least one episode of exposure to such energetic particles as cosmic rays; measurements of such exposure allow determination of how long a meteorite existed as a meter-sized body prior to earth impact. Meteorite exposure to energetic particles before their ejection from a parent body entails that the meteorite reside in the upper several m of that parent regolith. At the periods closest to the 4.6 billion year horizon, early solar system conditions may have been characterized by much gas and dust; irradiation records from this period may prove invaluable in reconstructing its characteristics.

Caffee, M. W.↗
NASA NTRS2004

New Measurements of Aerosol Vertical Structure from Space using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth,s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GLAS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output.

Welton, E. J.↗
NASA NTRS2003

New Measurements of Aerosol Vertical Structure from Space Using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GUS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output,

Welton, Ellsworth J.↗
NASA NTRS2003

Laboratory performance of the Keck interferometer nulling beam combiner

Now that regular visibility squared measurements are routinely achieved, mid-infrared nulling is the next observing mode to be implemented on the Keck Interferometer. This mode's main objective is the characterization of exo-zodiacal dust disks around nearby main sequence stars in support of the TPF space mission. Keck Nuller also shares numerious characteristics with an interferometric TPF, and will then serve as a technical precursor for this mission. We report here the results obtained in the laboratory with the KI mid-IR nulling beam combiner, which is based on a dual polarization Modified Mach Zender combiner and dispersion and achromatic nulling through zinc-selenide dielectric plates.

mid-infrared↗
NASA NTRS2006

Working Group Reports and Presentations: Cis-lunar

Space agencies are committed to the "safe, sustained, affordable human and robotic exploration of the Moon, Mars, and beyond." However, we recommend that they explicitly define our ultimate goal and motivation in order to portray a sense of purpose to the public. Our goal is sustainable human settlement of the Moon and Mars and our motivation is to preserve the human race. All secondary exploration and science objectives flow from this main goal and are still imperative to our success. As an economic guiding principle, governments should be limited to those areas where only government can perform the activity and should recognize and coordinate with the larger private and military sectors. Also, space agencies must continue to fund the interdisciplinary science necessary to characterize environmental hazards associated with dust, radiation, surface charging, topology, and meteorites in order to make our first attempts at extraterrestrial living viable.

Laubscher, Bryan↗
NASA NTRS2005

Evaluation of Aerosol Properties over Ocean from Moderate Resolution Imaging Spectroradiometer (MODIS) during ACE-Asia

The Aerosol Characterization Experiment-Asia (ACE-Asia) was conducted in March-May 2001 in the western North Pacific in order to characterize the complex mix of dust, smoke, urban/industrial pollution, and background marine aerosol that is observed in that region in springtime. The Moderate Resolution Imaging Spectroradiometer (MODIS) provides a large-scale regional view of the aerosol during the ACE-Asia time period. Focusing only on aerosol retrievals over ocean, MODIS data show latitudinal and longitudinal variation in the aerosol characteristics. Typically, aerosol optical depth (tau(sub a)) values at 0.55 micrometers are highest in the 30 deg. - 50 deg. latitude band associated with dust outbreaks. Monthly mean tau(sub a) in this band ranges approx. 0.40-70, although large differences between monthly mean and median values indicate the periodic nature of these dust outbreaks. The size parameters, fine mode fraction (eta), and effective radius (r(sub eff)) vary between monthly mean values of eta = 0.47 and r(sub eff)= 0.75 micrometers in the cleanest regions far offshore to approximately eta = 0.85 and r(sub eff) =.30 micrometers in near-shore regions dominated by biomass burning smoke. The collocated MODIS retrievals with airborne, ship-based, and ground-based radiometers measurements suggest that MODIS retrievals of spectral optical depth fall well within expected error (DELTA tau(sub a) = plus or minus 0.03 plus or minus 0.05 tau(sub a)) except in situations dominated by dust, in which cases MODIS overestimate both the aerosol loading and the aerosol spectral dependence. Such behavior is consistent with issues related to particle nonsphericity. Comparisons of MODIS-derived r(sub eff) with AERONET retrievals at the few occurrences of collocations show MODIS systematically underestimates particle size by 0.2 micrometers. Multiple-year analysis of MODIS aerosol size parameters suggests systematic differences between the year 2001 and the years 2000 and 2002, which are traced to instrumental electronic cross talk. Sensitivity studies show that such calibration errors are negligible in tau(sub a) retrievals but are more pronounced in size parameter retrievals, especially for dust and sea salt.

Chu, D. A.↗
NASA NTRSDate not supplied

A Rather Thick, Multilayered, Accretionary Rim on A Rather Large CAI in the NWA 10758 CV3 Chondrite

Northwest Africa (NWA) 10758 is a Bali type oxidized CV3, and section JSC1 contains a large (~ 2.4 x 1.4 cm), melilite-rich, type A Ca-Al rich inclusion (CAI), briefly introduced by Ross et al. [1]. The exceptional feature of this CAI is a thick (locally >5mm) fine- to coarse-grained, accretionary rim exhibiting at least 6 distinct layers. As such, this rim may sample a very wide region of the nebula, and mineralogically-diverse “clouds” of dust, and thus warrants detailed characterization.

M. Zolensky↗
NASA NTRS2024

A Multilayered Accretionary Rim on a CAI in the NWA 10758 CV3 Chondrite

Northwest Africa (NWA) 10758 is a Bali type oxidized CV3 chondrite, and section JSC1 contains a large (~2.4×1.4 cm), melilite-rich, type A Ca-Al rich inclusion (CAI), briefly introduced before [1,2]. The exceptional feature of this CAI is a thick (locally >5 mm) fine- to coarse-grained, accretionary rim exhibiting at least 6 distinct layers (Fig. 1). This rim may have formed during passage of the still hot CAI through diverse “clouds” of dust, and thus warrants detailed characterization.

M. Zolensky↗
NASA NTRS1976

Mariner 9 ultraviolet spectrometer experiment - Bright-limb observations of the lower atmosphere of Mars

Analysis of the bright-limb profiles obtained by the Mariner 9 ultraviolet spectrometer during the December 1971 dust storm on Mars shows that the dust extended to an altitude of plus or minus 10 km, with a sharp cutoff in altitude distribution. Above the dust layer, the reflected signal is characterized by Rayleigh scattering in the wavelength interval 2100 to 3500 A. Detached haze layers were detected at an altitude of 70 plus or minus 10 km at the top of the dust layer. The haze layers have a nominal optical thickness of about 0.0001 and a geometrical thickness of 3 to 10 km and are probably a condensate of small CO2 or H2O ice particles (mean radius less than 0.1 micron). Similar features were revealed in Mariner 9 TV pictures of the limb.

Ajello, J. M.↗
NASA NTRS2011

Mid-Infrared Imaging of Exo-Earths: Impact of Exozodiacal Disk Structures

The characterization of Earth-like extrasolar planets in the mid-infrared is a significant observational challenge that could be tackled by future space-based interferometers. The presence of large amounts of exozodiacal dust around nearby main sequence stars represents however a potential hurdle to obtain mid-infrared spectra of Earth-like planets. Whereas the disk brightness only affects the integration time, the emission of resonant dust structures mixes with the planet signal at the output of the interferometer and could jeopardize the spectroscopic analysis of an Earth-like planet. Fortunately, the high angular resolution provided by space-based interferometry is sufficient to spatially distinguish most of the extended exozodiacal emission from the planetary signal and only the dust located near the planet significantly contributes to the noise level. Considering modeled resonant structures created by Earth-like planets, we address in this talk the role of exozodiacal dust in two different cases: the characterization of Super-Earth planets with single space-based Bracewell interferometers (e.g., the FKSI mission) and the characterization of Earth-like planets with 4-telescope space-based nulling interferometers (e.g., the TPF-I and Darwin projects). In each case, we derive constraints on the disk parameters that can be tolerated without jeopardizing the detection of Earth-like planets

Defrere, Denis↗
NASA NTRS1996

From Stardust to Planetesimals: Contributed Papers

On June 24 through 26, 1996, a scientific conference entitled From Stardust to Planetesimals was held at the Westin Hotel, Santa Clara, California, as part of the 108th annual meeting of the Astronomical Society of the Pacific. Over the last decade, our understanding of the formation and early evolution of the solar system has advanced considerably due to progress that has been made simultaneously on many fronts. Stardust has been isolated in meteorites and interplanetary dust particles (IDP's), providing us with sample materials which predate the solar system and which offer clues to the processing that has occurred. At the same time, infrared studies have led to a better characterization of the composition of interstellar dust, which is now readily accepted as an important component of the interstellar medium infrared observations have also provided a much better view of the star-formation process and the role of dust therein. Recently, the presence of Kuiper Belt planetesimals has been confirmed and spectroscopy of these rather pristine objects may soon become available. Analysis of spacecraft data from the Comet Halley flybys has yielded a wealth of information on the composition of this comet. These observational advances have changed our understanding of planetesimal processing. The launch of the Infrared Space Observatory, the opening of 10-meter class telescopes, and, in the longer term, the Rosetta mission, promise to continue to broaden and deepen our understanding of the evolution from stardust to planetesimals. For these reasons we considered it timely to organize a meeting focused on the processes that connect stardust and planetesimals. The goal of this meeting was, therefore, to bring together astronomers interested in star- and planet-formation, planetary scientists studying early solar system relics, laboratory scientists studying the processing of analogs, and scientists analyzing meteorites and interplanetary dust particles, grain by grain. As a result of this endeavor, over 200 participants, including 153 scientists from 14 different countries, gathered to discuss the origin and evolution of stardust. We hope that this encounter in Santa Clara will foster an ongoing interchange of information and ideas within this diverse group of scientists. A major aim of this meeting was to produce conference proceedings which reflect the current situation regarding the evolution from stardust to planetesimals.

Kress, M. E.↗
NASA NTRS2013

Spatial and Temporal Dust Source Variability in Northern China Identified Using Advanced Remote Sensing Analysis

The aim of this research is to provide a detailed characterization of spatial patterns and temporal trends in the regional and local dust source areas within the desert of the Alashan Prefecture (Inner Mongolia, China). This problem was approached through multi-scale remote sensing analysis of vegetation changes. The primary requirements for this regional analysis are high spatial and spectral resolution data, accurate spectral calibration and good temporal resolution with a suitable temporal baseline. Landsat analysis and field validation along with the low spatial resolution classifications from MODIS and AVHRR are combined to provide a reliable characterization of the different potential dust-producing sources. The representation of intra-annual and inter-annual Normalized Difference Vegetation Index (NDVI) trend to assess land cover discrimination for mapping potential dust source using MODIS and AVHRR at larger scale is enhanced by Landsat Spectral Mixing Analysis (SMA). The combined methodology is to determine the extent to which Landsat can distinguish important soils types in order to better understand how soil reflectance behaves at seasonal and inter-annual timescales. As a final result mapping soil surface properties using SMA is representative of responses of different land and soil cover previously identified by NDVI trend. The results could be used in dust emission models even if they are not reflecting aggregate formation, soil stability or particle coatings showing to be critical for accurately represent dust source over different regional and local emitting areas.

spectral mixing analysis↗
NASA NTRS1980

Physical and dynamical conditions in interstellar clouds

Techniques for measuring the local and global parameters that describe molecular clouds are presented and illustrated by selected results. The local parameters which characterize a given location in a cloud are gas kinetic temperature, dust temperature, total density, magnetic field strength, abundance of species i, volume cooling and heating rates for gas and dust, and the thermal and turbulent velocities. Global properties which characterize the cloud as a whole include the size expressed as a length or area, the orientation and shape, the mass, and the integrated heating and cooling rates. If the cloud as a whole is collapsing or rotating, then the collapse velocity and the rotational velocity or angular momentum are global properties. An intermediate class of parameters which shares features of local and global properties includes the column density of species i, the total column density, and the average density.

Evans, N. J., II↗
NASA NTRS2000

Airborne Aerosol Closure Studies During PRIDE

The Puerto Rico Dust Experiment (PRIDE) was conducted during June/July of 2000 to study the properties of Saharan dust aerosols transported across the Atlantic Ocean to the Caribbean Islands. During PRIDE, the NASA Ames Research Center six-channel (380 - 1020 nm) airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane alongside a suite of in situ aerosol instruments. The in situ aerosol instrumentation relevant to this paper included a Forward Scattering Spectrometer Probe (FSSP-100) and a Passive Cavity Aerosol Spectrometer Probe (PCASP), covering the radius range of approx. 0.05 to 10 microns. The simultaneous and collocated measurement of multi-spectral aerosol optical depth and in situ particle size distribution data permits a variety of closure studies. For example, vertical profiles of aerosol optical depth obtained during local aircraft ascents and descents can be differentiated with respect to altitude and compared to extinction profiles calculated using the in situ particle size distribution data (and reasonable estimates of the aerosol index of refraction). Additionally, aerosol extinction (optical depth) spectra can be inverted to retrieve estimates of the particle size distributions, which can be compared directly to the in situ size distributions. In this paper we will report on such closure studies using data from a select number of vertical profiles at Cabras Island, Puerto Rico, including measurements in distinct Saharan Dust Layers. Preliminary results show good agreement to within 30% between mid-visible aerosol extinction derived from the AATS-6 optical depth profiles and extinction profiles forward calculated using 60s-average in situ particle size distributions and standard Saharan dust aerosol refractive indices published in the literature. In agreement with tendencies observed in previous studies, our initial results show an underestimate of aerosol extinction calculated based on the in situ size distributions relative to the extinction obtained from the sunphotometer measurements. However, a more extensive analysis of all available AATS-6 and in situ size distribution data is necessary to ascertain whether the preliminary results regarding the degree of extinction closure is representative of the entire range of dust conditions encountered in PRIDE. Finally, we will compare the spectral extinction measurements obtained in PRIDE to similar data obtained in Saharan dust layers encountered above the Canary Islands during ACE-2 (Aerosol Characterization Experiment) in July 1997. Thus, the evolution of Saharan dust spectral properties during its transport across the Atlantic can be investigated, provided the dust origin and microphysical properties are found to be comparable.

Redemann, Jens↗
NASA NTRS2003

A P-band Radar Mission to Mars

Large regions of Mars are covered by dust that obscures geological evidence for fluvial channels, the extent of volcanic flows, and features associated with near-surface ground ice. We describe a Mars orbiting mission carrying a P-band SAR to map these hidden surface features. Mapping would be carried out in HH and VV polarizations, with the comparison of the two expected to yield a distinction between surface echoes and subsurface features beneath up to 5 m of dust. Repeat-pass interferometry data would also be collected to characterize volatile migration at the poles, aeolian shifting of the dust mantle, and possible volcanic deformation. This paper describes the technical design of a P-band SAR for global mapping of Mars, and the characteristics of the proposed mission.

Synthetic Aperture Radar (SAR)↗
NASA NTRSDate not supplied

Electrostatic Charging of the Lunar Surface

Lunar regolith dust particles accumulate charge and interact electrostatically with rover wheels, astronaut boots, and equipment. We have developed instrumentation for in situ measurements of the electrostatic charge developed by the interactions of lunar regolith dust with the space-rated materials on these devices. This instrument is also capable of measuring the distribution of electric fields on or near the lunar surface and the ion currents present near the lunar surface. We also report on our efforts to characterize the charging behavior of lunar dust in low gravity environments. This behavior is nonintuitive due to complex interactions between individual dust grains. We are developing an experiment to study this interaction in a microgravity vacuum environment. Better understanding of this interaction will allow for improved dust mitigation on the lunar surface.

electrostatics↗