The research presented here represents the initial phase of a broader project that is intended to provide data in the mid- and far-IR spectral region for both well-characterized iron oxides/oxyhydroxides and poorly crystalline or amorphous materials (e.g., palagonites). Such information can be used in the interpretation of data to be returned by the Mars Observer Thermal Emission Spectrometer (TES). Additionally, this same information will prove useful for assessing the information content of existing Kuiper Airborne Observatory, Mariner 7, and Mariner 9 spectra. which also cover the thermal IR wavelength region

Bell, J. F., III

Roush, T. L.

English

NASA Technical Reports Server

2 Resuhsfrom the MSAT - ---.
N94-33192
¢'I P/es o Jx)
STATIONARY EDDIES IN THE MARS GENERAL CIR-
\ CULATION AS SIMULATED BY THE NASA-AMES GCM.J. R. Barnes 1, J. B. Pollack 2, and R. M. Haberle 2, IOregon State
University, Corvallis OR 97331, USA, -'NASA Ames Research
Center, Moffett Field CA 94035, USA.
LiZ-lo- ,-•-_ i]9
understandable in terms of differences in the topography in the two
hemispheres.
The stationary eddies in the northern winter extratropics are
found to increase in amplitude with dust loading. This behavior ap-
pears to be at least paaly associated with changes in the structure of
the zonal-mean flow that favor a greater response to wave I topo-
graphic forcing. There are also strong stationary eddy circulations in
the tropics and in the summer hemisphere. The eddies in the sum-
mer subtropics and exiratropics are substantially stronger in south-
err summer than in northern summer. The summer hemisphere
stationary cireulations are relatively shallow and are characterized by
craft over the past 20 years have revealed that the ferric mineralogy
occurs in two distinct forms: ( 1) nanophase or truly amorphous Fe 3÷-
bearing materials [ 14,15] that spectraily resemble certain terrestrial
palagonites [e.g., 16-20]; and (2) well-crystalline ferric oxides like
hematite ((t-Fe203) , maghemite (-?-Fe:O3) ' or magnetite (Fe304)
[I, 13,15,21-24]. The available data indicate that the poorly crystal-
line "palagonite-like" phases are spectrally dominant [e.g., 5,6, and
references within] and that the highly crystalline ferric oxides cannot
Quasistationary eddies are prominent in a large set of simulations
of the Mars general circulation performed with the NASA-Ames
GCM. Various spacecraft observations have at least hinted at the constitute an abundance of more than abou! 4-8 wt% [24].
existence of such eddies in the Mars atmosphere. The GCM station- = i-The _search--presen_ here represents the initial phase of a
ary eddies appear to be forced primarily by the large Mars topogra- broader project that is intended to provide data in the mid- and far-
phy, and (to a much lesser degree) by spatial variations in the surface ! ! IR spectral region for both well-characterized iron oxides/oxy-
albedo and thermal inertia. The stationary eddy circulations exhibit : ;hydroxides and poorly crystalline or amorphous materials (e.g.,
largest amplitudes at high altitudes (above 30-40 kin) in the winter _ palagonites). Such information can be used in the inte retation of
extratropical regions. In these regions they are of nlanetarv scale _ --data "^ "-................ rp
. -., , : . tu u_ zcturneo oy ine Mars uoserver I nermal Emission Spec-
characterized largely by zonal wavenumbers I and 2. Southern hemi- - _trometer (TES). Additionaliy_ ibis same in formation will prove
sphere winter appears to be dominated by a very strong wave I useful for assessing the information content of existing Kuiper
pattern, with both waves I and 2 being prominent in the northern _ Airborne Observatory, Mariner 7, and Mariner9spectra, whichalso
hemisphere winter regime. This difference seems to be basically "-cover the thermal IR wavelength region.
_ Spectral Studies: In the mid IR (5-25 pm), spectral features
arise from vibrational motions of atoms and molecules that compose
the materials. These fundamental modes are I-2 orders of magni-
tude more intense than any associated combination and/or overtones
of these modes that occur at wavelengths less than 5 lain, and hence
remote sensing observations in the IR are extremely sensitive to
-minor concentrations of these absorbing species.
From a planetary perspective, in the mid to far IR these diagnostic
features occur where thermal emission rather than reflected sunlight
supplies the observed photons. They occur under two sets of condi-
tions. First, suspended particles in a nonisothermal atmosphere pro-
smaller zonal scales than those in the winter cxtratropics, duce features near their vibrational fundamentals since these bands
< __-,._.modulate the wavelength behavior of both the extinction coefficient
5)- 7/ N94- 33193 ]ndthe single scattering albedo of the atmospheric layers within
THERMAL EMISSION MEASUREMENTS (5---'_2-5_'-pm)OF
.. HAWAIIAN PALAGONITIC SOILS WITH IMPLICA. Wavelength(/zm)
TIONS FOR MARS. J.F. Bell !11 i and T. L. Roush _, rMaiI _2s _oo B3 r_
Stop 245-3, NRC/NASA Ames Research Center, Moffett Field CA
94035-1000, USA, -'San Francisco State University and NASA
Ames Research Center, Mail Stop 245-3, Moffett Field CA 94035-
I000, USA.
Background: There is ample evidence that abundant Fe-bearing
minerals are present on Mars. This evidence takes the form ofinsitu
analyses [I-4], previous and continuing Earth-based telescopic
spectroscopic observations (reviewed in [5,6]), Viking Lander and
Orbiter muhispectral imaging [7-10], and Phobos 2 multispectral
imaging [11,12]. Information regarding the crystalline or amor-
phous nature of the Fe-bearing (and other) surface materials on
Mars can provide insight into the availability of liquid water at the
surface and the duration, mode, and extent of weathering.
Data from Viking X-ray fluorescence analyses, magnetic experi-
ments, and aerosol imaging were interpreted as indicating the pres-
ence of a variety of Fe-rich materials, including iron oxides [ I-4,13].
However, since the Viking Landers did not carry any instruments
capable of determining mineralogy, the exact mineralogical form of
the Fe-bearing material remains uncertain.
Interpretations of continuing visual, near-, mid-, and far-infrared
(IR) spectroscopic observations of Mars from the Earth and space-
_>.
¢i
ud
,, 250 167 63 56 50
'L'''I'''I'''I '''l'',i_,_t= , ,, ,
• "....-\(B)
(B) PH-I, < 20 /a'n H-O-H "._,
•.. (o)
(C) 91-I, 500-1000 _ "V,
(D) 91-1. < 20 pm _.,%_
-,I,,,I,j jl,,, I ,,,I ,,,I,,,I,,,I,,,I,
400 600 BOO 1000 '1200 1400 1600 1800 200
Wavenumber(cm")
Fig. l. EmissivityspectraofHawaiianpalagoniticsamplesPH.l (thermally
altered palagonitic tephra from Mauna Kea) and 91 - l (palagonitic tephra from
South Point, island of Hawaii). Both coarse and fine size fraction sgectra are
shown. Arrows indicate subtle shifts inemissivity peak position between the two
particle size regimes shown.The vertical line shows the frequency of the strong
,H-O-H bending fundamenlalcaused by molecular water associated with these
samples.
https://ntrs.nasa.gov/search.jsp?R=19940028687 2020-06-16T12:15:10+00:00Z
LP! TechnicaI Report 93-06, Part I 3
which they reside [25]. Second, solid and particulate surfaces ex-
hibit spectral features in the thermal IR domain due tO a spectral
dependence of the surfaces' emissivity [e.g., 26,27].
Careful laboratory studies have shown that the coloring agent in
certain Mars analog Hawaiian palagonitic soils is nanophase iron
oxide [18,19,28]. We have measured the emissivity of two Mauna
Kea palagonitic soils whose transmission spectra exhibit different
spectral features [29] and of a thermally altered volcanic tephra
sample that exhibits a wide range of crystallinity and degree of
alteration (from black cinders to fully hematitic) [19]. Both of these
samples may represent analogs for formation mechanisms involving
the production of highly altered secondary weathering products on
Mars. The emission spectra of all samples were measured at the TES
spectroscopy laboratory [30] at Arizona State University with the
cooperation of Dr. P. Christensen. The data were converted to emis-
sivity using blackbody measurements combined with measurements
of each sample at different temperatures [31 ].
[23] Hargraves R. B. et al. (1979)JGR, 84, 8379. [24] Bell J. F. III
(1992) Icarus, 100, 575. [25] Toon O. B. et al. (1977) Icarus, 30,
663. [26] Salisbury J. W. and Eastes J. W. (1985) Icarus, 64, 586.
[27] Salisbury j. W. et al. (1987)JGR, 92,702. [28] Golden D. C.
et al. (1993)JGR, 98, 3401. [29] Roush T. L. (1992) LPI Tech. Rpt.
92-04, 32. [30] Anderson D. L. et al. (1991) LPS XXII, 21.
[31] Christensen P. R. and Harrison S. T. (1993) JGR, submitted.
[32] Salisbury J. W. et al. (1991) Infrared (2.1-25 tmO Spectra of
Minerals, 267, Johns Hopkins Univd
N94. 33194
THERMAL STUDIES OF MARTIAN CHANNELS AND
VALLEYS USING TERMOSKAN DATA: NEW RESULTS.
B. H. Betts I.-_ and B. C. Murray 1, 1Mail Code 170-25, California
Institute of Technology, Pasadena CA 91125, USA, -_Now at San
Juan Capistrano Research Institute, 31872 Camino Capistrano, San
Results: Emissivity spectra for coarse and fine panicle size Juan Capistrano CA 92675, USA. _
separates of each sample are shown in Fig. 1. Several trends are
m : =
immediately obvious. First, the finer panicle size fractions exhibit _'-'_The Termoskan instrument onboard the Phobos '88 spacecraft
increasingly loweremissivity than the coarser sizes at wavenumbers' acquired the highest-spatial-resolution thermal data ever obtained
above 1400 cm -T. This effect may be a manifestation ofthe increased _ for Mars [ l-3]_In_luded in the thermal images are 2 km/pixel mid-
importance of multiple scattering at these frequencies rather than _ day observations of several major channel and valley systems (see ;
Fresnel-like reflections at lower frequencies. Second, emissivity : Fig. I), includlng significant portions of Shalbatana Vallis, Ravi
peaks in the 1000-1400 cm -n region in the fine fraction samples are _ Vallls, AI-Qahira Vallis, Ma'adim Vallis, the channel connecting
shifted to higher frequencies relative to the same feature in the ° Valles Marineris with Hydraotes Chaos, and channel material in
coarse fraction samples. This may be a panicle size effect or it may _ Eos Chasma. Termoskan also observed small portions of the south-
be due to variations in the silicate and/or Fe-bearing mineralogy " ern beginnings of Simud, Tiu, and Ares Valles and some channel
between the coarse and fine samples [e.g., 191. While we do not material in Gangis Chasma. Simultaneous broad band visible data
make specific mineralogie assignments for the various spectral were obtained for all but Ma'adim Vallis. Here we present new
features seen in these data, we note that a broad emissivity peak = results that go beyond the analysis presented in [41.
possibly due to silicates is present near 1200-1300 cm -1 and that We find that most of the channels and valleys have higher
narrower features near 1403-1600 cm -T and near 400 cm-I are
possibly consistent with crystalline iron oxide minerals like hema-
tite and/or goethite [32].
This preliminary study has demonstrated that naturally occurring -
palagonites, thought to be good visible to near-IR spectral analogs
for Mars, exhibit complex emissivity spectra at thermal wavelengths.
Disentangling the various spectral signatures that make up the emis-
sivity spectra of these complex assemblages may prove quite impor-
tant in the interpretation of the Mars Observer TES data and of other
mid-lR Mars datasets.
References: [ 11 Hargraves R. B. et al. (1977) JGR, 82, 4547.
[2] Toulmin P. et al. (1977) JGR, 82, 4625. [3] Clark B. C. et al.
(I 977) JGR, 82, 4577. [4] Clark B. C. et al. (1982) JGR, 87, 10059.
inertias than their surroundings, consistent with Viking IRTM-
based thermal studies of martian channels [e.g., 5--8]_ We see for the
first time that thermal inertia boundaries closely match all flat
channel floor boundaries. Combining Termoskan thermal data,
relative observations from Termoskan visible channel data, Viking
absolute bolometric albedos from [9T,_d a thermal model of the
Mars surface based upon [10_.F,_e have derived lower bounds on
channel thermal inertias. Lower bounds on typical channel thermal
inertias range from 8.4 to 12.5 (I 0-3 cal cm -2 s-J'2 K-l) (352 to 523
in SI units). Lower bounds on inertia differences with the surround-
ing heavily cratered plains range from 1.1 to 3.5 (46 to 147 in SI
units).
Atmospheric and geometric effects are not sufficient to cause the
[5] Soderblom L. A. (1992) inMars (H. H. Kieffer et al., eds.), 557. inertia enhancements. We agree with previous researchers [5,6,8]
[6] Roush T. L. et al. (1993) in Remote Geochemical Analysis (C. - that localized, dark, high inertia areas within channels are likely
Pieters and P. Englert, eds.), 367. [7] Soderblom L. A. et al. (1978) eolian in nature. However, the Termoskan data show that eolian
Icarus, 34, 446. [8] McCord T. B. et al. (1982) JGR, 87, 10129. _ deposits do not fill the channels, nor are they responsible for the
[9] AdamsJ.B.etal.(1986)JGRigl,gO98.[lO]ArvidsonR.E.et al. overall thermal inertia enhancement, contrary to the 1RTM-based-
(I 989)JGR, 94, 1573. [ I 1] Murchie S. et al. (1993) Icarus, in press, conclusions of [6] and [8]. Thermal homogeneity and strong corre-
[I 2] Mustard J. F. et al. (1993) JGR, 98, 3387. [I 3] Pollack J. B. = lation of thermal boundaries with the channel floor boundaries lead
et al. (1977) JGR, 82, 4479. [14] Morris R. V. and Lauer H. V. Jr. - us t9 favor noneolian overall explanations.
(1990)JGR, 95, 5101. [ 15] Morris R. V. et al. (I 989)JGR, 94, 2760.
[16] Singer R. B. et al. (1979) JGR, 87, 10159. [ 17] Evans D. L. and
Adams J. B. (I 980) LPS XI, 757. [18] Morris R. V. et al. ( 1990)JGR,
95, 14427. [ 19] Bell J. F. III et al. (1993) JGR, 98, 3373. [20] Banin
A. (1992) LPI Tech. Rept. 92-04, 1. [21] Morris R. V. et al. (1985)
JGR, 90, 3126. [22] Bell J. F. II1 et al. (1990) JGR, 95, 14447.
Higher inertia channel floors do not appear to be associated with
catastrophic flood channels, although very few of these were ob-
served. Eastern Ravi and southern Ares Vallis are the only two
major channel segments observed that are not thermally distinct.
They do not have flat floors. In contrast, channel floor inertia
enhancements are strongly associated with channels showing fret-


Thermal emission measurements (5-25 microns) of Hawaiian palagonitic soils with implications for Mars

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