The Thermal Emission Imaging System (Themis) for the Mars 2001 Odyssey Mission

Christensen, P. R.; Jakosky, B. M.; Kieffer, H. H.; Malin, M. C.; McSween, H. Y.; Nealson, Kenneth H.; Mehall, G.; Silverman, Sam; Ferry, Steven; Caplinger, M. A.; Ravine, M. A.

doi:10.1007/978-0-306-48600-5_3

Cited by 715 publications

(479 citation statements)

References 90 publications

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“…Looking at the latitude range from 50 to 90°S, previous work by Fenton and Hayward (2010) mapped and categorized dune fields into six morphological classes based on an inferred level of stability visible in Thermal Emission Imaging System (THEMIS) visible (VIS) (Christensen et al, 2004), Context Camera (CTX) (Malin et al, 2007), and Mars Orbiter Camera (MOC) (Malin et al, 1991) images (see Figure 2); this selection of images collectively offered suitable coverage of dune fields for feature identification and classification. As part of an update to the MGD 3 , all other dune fields in the south polar and equatorial MGD 3 (spanning 90°S to 65°N) were later categorized into these six morphological classes (Gullikson et al, 2018) using the same methods as Fenton and Hayward (2010).…”

Section: Introductionmentioning

confidence: 99%

Patterns in Mobility and Modification of Middle‐ and High‐Latitude Southern Hemisphere Dunes on Mars

et al. 2018

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Change detection analyses of aeolian bedforms (dunes and ripples), using multitemporal images acquired by the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (HiRISE), can reveal migration of bedforms on Mars. Here we investigated bedform mobility (evidence of wind‐driven migration or activity), from analysis of HiRISE temporal image pairs, and dune field modification (i.e., apparent presence/lack of changes or degradation due to nonaeolian processes) through use of a dune stability index or SI (1–6; higher numbers indicating increasing evidence of stability/modification). Combining mobility data and SI for 70 dune fields south of 40°S latitude, we observed a clear trend of decreasing bedform mobility with increasing SI and latitude. Both dunes and ripples were more commonly active at lower latitudes, although some high‐latitude ripples are migrating. Most dune fields with lower SIs (≤3) were found to be active while those with higher SIs were primarily found to be inactive. A shift in prevalence of active to apparently inactive bedforms and to dune fields with SI ≥ 2 occurs at ~60°S latitude, coincident with the edge of high concentrations of H2O‐equivalent hydrogen observed by the Mars Odyssey Neutron Spectrometer. This result is consistent with previous studies suggesting that stabilizing agents, such as ground ice, likely stabilize bedforms and limit sediment availability. Observations of active dune fields with morphologies indicative of stability (i.e., migrating ripples in SI = 3 dune fields) may have implications for episodic phases of reworking or dune building, and possibly geologically recent activation or stabilization corresponding to shifts in climate.

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Section: Introductionmentioning

confidence: 99%

Patterns in Mobility and Modification of Middle‐ and High‐Latitude Southern Hemisphere Dunes on Mars

et al. 2018

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“…It is thus the longest surviving orbiting imager. Images are taken with the Thermal Emission Imaging System (THEMIS) (Christensen et al, 2004), which consists of THEMIS-VIS for images and the THEMIS-IR for infrared images. The nominal target for the THEMIS-VIS was to map 60% of the Martian surface with resolution of 18 metres per pixel, but due to its longevity it has significantly surpassed this limit.…”

Section: Materials and Methodsologymentioning

confidence: 99%

Temporal analysis of all high-resolution Mars imaging products

Sidiropoulos

Müller

2014

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:A meta-data analysis has been performed of high-resolution imagery that have been acquired over the last four decades from Mars. More specifically, we are interested in two independent image parameters, the time that each image was acquired and the spatial resolution with which the planetary region is mapped in the image. We are only interested in mapping changes in high-resolution images. We use two different upper thresholds to discriminate them from low-resolution images, twenty metres and a hundred metres per pixel. In order to be able to extract semantic information about the temporal and spatial distribution of high-resolution Martian imagery we adopt two grouping strategies. In the first, images are clustered according to the time period (counted in Martian Years) that they were acquired, so as to examine whether sporadic Martian phenomena can be identified (e.g. a new crater) from imagery that depict the same area in different time periods. In the second grouping, images are clustered according to the Martian season that they were acquired, so as to examine whether seasonal Martian phenomena can be identified from imagery that depict the same area during the same season. This analysis supports the hypothesis that there is sufficient coverage for both tasks, since the Martian surface has been mapped at least once in each epoch and more than twice since 2002 and for each season at least 10% of Martian surface has been mapped at least three times. The resulting maps and graphical plots will be presented will provide additional detail to this report. * Corresponding Author

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“…This work describes and provides age estimates for two types of features identified within the valles: a complex shield-like structure on top of a mesa in Niger Vallis (henceforth Niger shield) and simple knobs with summit pits on Dao Vallis head floor (henceforth Dao pitted knobs). The used data (Zuber et al, 1992;Smith et al, 2001;Christensen et al, 2004;Neukum et al, 2004;Jaumann et al, 2007;Malin et al, 2007;McEwen et al, 2007) and methods (CATWG, 1979;Neukum, 1984;Hartmann and Neukum, 2001;Ivanov, 2001;Kneissl et al, 2011) are described in the supporting information. Volcanic vents directly associated with outflow channels are not entirely unexpected, as various other Martian outflow channels have been modified by volcanism in addition to fluvial activity (e.g., Chapman et al, 2010;Jaeger et al, 2007;Keske et al, 2015;Keske & Christensen, 2017).…”

Section: Introductionmentioning

confidence: 99%

Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

Korteniemi¹,

Kukkonen

2018

Geophysical Research Letters

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Outflow channel formation on the eastern Hellas rim region is traditionally thought to have been triggered by activity phases of the nearby volcanoes Hadriacus and Tyrrhenus Montes: As a result of volcanic heating subsurface volatiles were mobilized. It is, however, under debate, whether eastern Hellas volcanism was in fact more extensive, and if there were volcanic centers separate from the identified central volcanoes. This work describes previously unrecognized structures in the Niger‐Dao Valles outflow channel complex. We interpret them as volcanic edifices: cones, a shield, and a caldera. The structures provide evidence of an additional volcanic center within the valles and indicate volcanic activity both prior to and following the formation of the outflow events. They expand the extent, type, and duration of volcanic activity in the Circum‐Hellas Volcanic Province and provide new information on interaction between volcanism and fluvial activity.

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The Thermal Emission Imaging System (Themis) for the Mars 2001 Odyssey Mission

Cited by 715 publications

References 90 publications

Patterns in Mobility and Modification of Middle‐ and High‐Latitude Southern Hemisphere Dunes on Mars

Patterns in Mobility and Modification of Middle‐ and High‐Latitude Southern Hemisphere Dunes on Mars

Temporal analysis of all high-resolution Mars imaging products

Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

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