Preliminary assessment of Termoskan observations of Mars

Murray, Bruce C.; Naraeva, M. K.; Selivanov, A. S.; Betts, Bruce; Svítek, T.; Kharlamov, V. D.; Romanov, A. V.; Santee, M. L.; Gektin, Yu. M.; Fomin, D. A.; Paige, D. A.; Panfilov, A. S.; Crisp, David; Head, J. W.; Murchie, S. L.; Martin, T. Z.

doi:10.1016/0032-0633(91)90147-3

Cited by 10 publications

(7 citation statements)

References 14 publications

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“…The inertias derived from all the models are consistent with dust-sized particles. This is consistent with previous studies that proposed that the Tharsis region has a dust covering and is currently an area of dust deposition [Kieffer et al, 1977; Zirnbelrnan and KieJ•r, 1979; Palluconi and Kieffer, 1981;Christensen, 1986b]. It is also reasonably consistent with the low rock abundances (about 5%) in this region [Christensen, 1982[Christensen, , 1983[Christensen, , 1986a.…”

Section: Arsia Occurrencesupporting

confidence: 92%

“…Herschel occurrence. The inertia lower bound of 80 (2) that we derive for the Herschel occurrence is consistent with diurnal inertias for the shadowed region: 198-252 (4.7-6.0) [Hayashi et aI., this issue] and 239-301 (5.7-7.2) [palluconi and Kieffer, 1981]. These diurnal inertias are consistent with a homogeneous surface of sand-sized particles.…”

Section: Arsia Occurrencesupporting

confidence: 86%

“…Thus, beginning of eclipse and position in the scan. We then used this Tennoskan's instantaneous field of view rocked into and out of in three different one-dimensional, finite difference thermal observing the shadow (see Murray et al [1991] Table 1. diurnal thermal model (as discussed in the appendix).…”

Section: Mars' Surface However Because the Spacecraft And Moon Werementioning

confidence: 99%

“…However, the following factors make more accurate constraint impossible: (1) The Herschel occurrence was much cooler than the Arsia occurrence due primarily to the earlier morning observations as well as the inherently higher diurnal inertias in the Herschel region. Termoskan had less sensitivity at cooler temperatures (see Murray et al [ 1991 ] or Betts [ 1993] for the infrared response characteristics), e.g., 3 DN at 230 K correspond to about 2.5 K, but 3 DN at 255 K (characteristic of the Arsia occurrence) correspond to approximately 1.5 K. (2) Due to the strong dependence of the radiative cooling rate upon temperature, less shadow-induced cooling occurs when the initial temperatures are cooler. (3) The surface temperature drop during eclipse is very nonlinear with inertia, which causes less precision distinguishing between high inertia values than between low inertia values.…”

Section: Arsia Occurrencementioning

confidence: 99%

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Thermal inertias in the upper millimeters of the Martian surface derived using Phobos' shadow

Betts¹,

Murray²,

Svítek³

1995

J. Geophys. Res.

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Abstract. The first thermal images of Phobos' shadow on the surface of Mars, in addition to simultaneous visible images, were obtained by the Phobos '88 Termoskan instrument. The best observed shadow occurrence was on the flanks of Arsia Mons. For this occurrence, we combined the observed decrease in visible illumination of the surface with the observed decrease in brightness temperature to calculate thermal inertias of the Martian surface. The most realistic of our three models of eclipse cooling improves upon our preliminary model by including nonisothermal initial conditions and downward atmospheric flux. Most of our derived inertias fall within the range 38 to 59 J m ': s 4n K 4 (0.9 to 1.4 10 -3 cal cm ': s 4a K4), corresponding to dust-sized particles (for a homogeneous surface), consistent with previous theories of Tharsis as a current area of dust deposition. Viking infrared thermal mapper (IRTM) inertias are diurnally derived and are sensitive to centimeter depths, whereas the shadow-derived inertias sample the upper tenths of a millimeter of the surface. The shadowderived inertias are lower than those derived from Viking IRTM measurements (84 to 147), however, uncertainties in both sets of derived inertias make conclusions about layering tenuous. Thus, near-surface millimeter versus centimeter layering may exist in this region, but if it does, it is likely not very significant. Both eclipse and diurnal inertias appear to increase near the eastern end of the shadow occurrence. We also analyzed a shadow occurrence near the crater Herschel that showed no observed cooling. This analysis was limited by cool morning temperatures and instrument sensitivity, but yielded a lower bound of 80 on eclipse inertias in that region. Based upon our results, we strongly recommend future spacecraft thermal observations of Phobos' shadow, and suggest that they will be most useful if they improve upon Termoskan's geographic and temporal coverage and its accuracy.

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Section: Arsia Occurrencesupporting

confidence: 92%

Section: Arsia Occurrencesupporting

confidence: 86%

Section: Mars' Surface However Because the Spacecraft And Moon Werementioning

confidence: 99%

Section: Arsia Occurrencementioning

confidence: 99%

See 2 more Smart Citations

Thermal inertias in the upper millimeters of the Martian surface derived using Phobos' shadow

Betts¹,

Murray²,

Svítek³

1995

J. Geophys. Res.

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“…Hence, accurate bolometric Bond albedo information would be necessary to determine absolute thermal inertias. Due to instrument limitations, atmospheric variations, and very limited phase angle viewing geometry, even approximate estimates of Bond albedo have thus far not yielded high confidence results [Murray et al, 1991;Betts, 1993]. Therefore, we use only relative thermal inertias and qualitative visible differences across craters in our analysis.…”

Section: Gel'hod Of Obsf_rvation Andmentioning

confidence: 99%

Thermally distinct ejecta blankets from Martian craters

Betts¹,

Murray²

1993

J. Geophys. Res.

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Utilizing the Termoskan data set of the Phobos '88 mission we have recognized a new feature on Mars: ejecta blanket distinct in the thermal infrared (EDITH). Virtually all of the more than 100 features discovered in the Termoskan data are located on the plains near Valles Marineris. EDITHs have a startlingly clear dependence upon terrains of Hesperian age, implying a spatial or temporal dependence on Hesperian terrains. Almost no thermally distinct ejecta blankets are associated with any of the thousands of craters within the data set that occur on the older Noachian units. EDITHs also do not appear on the portions of the younger Tharsis Amazonian units seen in the data. The Hesperian terrain dependence cannot be explained by either atmospheric or impactor variations; Noachian and Hesperian terrains must have experienced identical atmospheric and impactor conditions during Hesperian times. Thermally distinct ejecta blankets therefore reflect target material differences and/or secondary modification processes. Not all lobate ejecta blankets are thermally distinct, but all EDITHs correlated with visibly discernible ejecta blankets are associated with lobate ejecta blankets. The boundaries of the thermally distinct areas usually follow closely the termini of the fluidized lobate ejecta blankets, even when the ejecta blankets show a high degree of sinuosity. Thus, the thermally distinct nature of EDITHs must be due to the primary ejecta formation process. The coupling of these thermal anomalies to morphology is unlike most sharp Martian inertia variations which are decoupled from observed surface morphology. Some thermally distinct ejecta blankets occur near otherwise similar craters that do not have thermally distinct ejecta blankets. Thus, wind patterns or locally available aeolian material cannot provide a single overall explanation for the observed variations. We compiled a data base of 110 EDITH and non-EDITH craters ranging in diameter from 4.2 km to 90.6 km. There are almost no correlations within the data base other than occurrence on Hesperian terrains. We postulate that most of the observed EDITHs are due to excavation of thermally distinctive Noachian age material from beneath a relatively thin layer of younger, more consolidated Hesperian volcanic material. The plausibility of this theory is supported by much geological evidence for relatively thin near-surface Hesperian deposits overlying massive Noachian megabreccias on the EDITH-rich plains units. We suggest that absence of thermally distinct ejecta blankets on Noachian and Amazonian terrains is due to absences of distinctive near-surface layering. Thermally distinct ejecta blankets are excellent locations for future landers and remote sensing •cause of relatively dust free surface exposures of material excavated from depth. . Laboratory experiments that vary atmospheric pressure and particle size have also reproduced some lobate crater morphologies Gault, 1979, 1984]. One of our motivations in studying Martian thermally distinct ejecta blankets in d...

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The Martian Surface Composition

Bibring

Érard

2001

Space Sciences Series of ISSI

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Preliminary assessment of Termoskan observations of Mars

Cited by 10 publications

References 14 publications

Thermal inertias in the upper millimeters of the Martian surface derived using Phobos' shadow

Thermal inertias in the upper millimeters of the Martian surface derived using Phobos' shadow

Thermally distinct ejecta blankets from Martian craters

The Martian Surface Composition

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