Layered Deposits (ESP_070261_1605) - Request submitted: March 11, 2021; Request scheduled: July 14, 2021; Request fulfilled: July 23, 2021. This observation targets a linear valley exposing light-toned layered materials in cliffs, seen in CTX image P12_005540_1595_XI_20S317W. Possible layering is observed in a rugged central ridge down to the resolution limits of CTX. Two small (< 250 m) dark-toned knobs are also visible jutting from the northern wall of the valley. The goal of this observation is to document layering at sub-meter resolution.
Resolution Justification: Layering occurs down to the resolution of CTX imaging, suggesting the presence of thin layering. Increased resolution will help place lower bounds on the scale of layering.
Cratered Cone in Terra Cimmeria (ESP_070429_1500) - Request submitted: May 27, 2021; Request scheduled: July 26, 2021; Request fulfilled: August 5, 2021 This observation targets a ~700 m wide cone located along the headwall of a valley incised in a crater rim deposit. This crater contains a shallow, elongated dome roughly oriented along the valley axis. This crater appears to have a rim of more resistant material. The appearance of the cone strongly resembles a cinder cone or spatter cone. High-resolution imagery of this feature will allow comparison to surrounding materials in terms of texture and color.
Resolution Justification: If targeted feature is a cinder cone, small boulders produced as large volcanic ejecta should be visible. More generally, high-resolution textural comparisons between the cone and surrounding crater rim materials will be useful in interpreting origins.
Possible Chloride-Rich Deposits Source Materials (Stereo Images ESP_070745_1540 and ESP_071734_1540) - Request submitted: July 6, 2020; Request scheduled: August 24, 2021; Request fulfilled: August 29, 2021. This observation studies the degraded ejecta blanket from a 20 km crater. The ejecta blanket contains small (5-10 m) exposures of a high albedo material north of the 1 km crater in the observation footprint. These materials may be the source of a chloride deposit in the adjacent high thermal inertia materials mapped by Osterloo et al 2010. The chloride deposit mapped by Osterloo et al is associated with sinuous exposures of material with a similar albedo and CTX texture. A hypothesis for their formation is that these materials were mobilized by runoff on the ejecta blanket, and deposited in a shallow depression behind a wrinkle ridge system. This observation targets the ejecta sheet to search for possible exposures of chloride-rich material in the ejecta sheet. In addition, it targets additional patchy exposures and sinuous exposures of chloride in the high thermal inertia materials.
Mound on Terra Cimmeria Crater Rim (ESP_071022_1550) - Request submitted: May 27, 2021; Request scheduled: September 16, 2021; Request fulfilled: September 21, 2021. This observation targets a ~850m wide mound located on the rim of a degraded 31 km crater. This mound loosely resembles a volcanic dome. It does not appear to have formed as the result of slumping along the crater rim, as it is circular (as opposed to more tabular slump blocks on the crater rim below it). This observation will compare the surface textures and properties of the mound with the material on the uplands surfaces outside the crater, as well as slump blocks and crater floor materials to the south of the mound.
Olivine-Rich Massif in Northeast Hellas Planitia (ESP_072594_1850) - Request submitted: December 5, 2018; Request scheduled: January 12, 2022; Request fulfilled: January 20, 2022. This observation targets banded terrain located in an olivine-rich massif in the Hellas Basin. The olivine-rich massifs have been interpreted as ejecta blocks excavated from the lower crust/upper mantle by the Hellas Basin impact (e.g. Ody et al. 2013). Thus, observations of these locations may investigation of deep crustal or mantle materials not otherwise exposed at the surface. Several large dike-like features are visible in CTX imagery of this massif. High-resolution imagery of the massif will be useful to evaluate whether these features were emplaced prior to or after the Hellas Basin impact.
Potentially Layered Bedrock Deposits in Terra Sabaea (ESP_072648_1515) - Request submitted: December 5, 2018; Request scheduled: January 17, 2022; Request fulfilled: January 25, 2022. This observation targets a region with suspected layered bedrock materials. The morphological texture of this target at CTX resolution is similar to other HiRISE observations in this region (ESP_044242_1520; ESP_057455_1520) where layered bedrock was found. The targeted area thus has a high probability of detecting layered bedrock. Imaging of this bedrock material will allow study of variations in the thickness and style of layering across this bedrock region.
Sinuous Ridges along Escarpment (ESP_072687_1605) - Request submitted: March 11, 2021; Request scheduled: January 17, 2022; Request fulfilled: January 28, 2022. This observation targets an escarpment along a graben in the Terra Sabaea highlands. In CTX image G19_025622_1619_XN_18S315W, the highlands massif contains several small (~250 m) knobs (targeted along the right edge of the requested footprint). The lower half of the massif is a darker-toned interval, with several low, wide sinuous ridges with branching morphologies emerging onto the graben floor. The light-toned graben floor bedrock appears to be composed of a layered material, with possible layered exposures targeted in the bottom half of the requested observation footprint. This observation seeks to characterize the morphology of the sinuous ridges at the meter-scale, as well as develop geologic context for their formation.
Resolution Justification: The sinuous ridges targeted are relatively small (some exposures < 50 m in width). Higher resolution increases the changes of detecting internal stratigraphy if present. In addition, possible layering within the graben floor unit appears as banding between 3-5 pixels across in CTX imagery. Increased resolution may resolve more additional layering within this unit.
Dome with Flow-Like Features (ESP_072709_1475) - Request submitted: November 27, 2019; Request scheduled: January 17, 2022; Request fulfilled: January 29, 2022. This observation targets a 900m tall dome that is 8km in diameter. No objects of comparable positive relief are located in its vicinity. CTX image P07_003584_1469_XN_33S195W indicates several lobate, flow-like structures emerging from craters in its flanks. These observations suggest that this dome is a volcanic ediface. The observation crosses the entire dome to study the feature with high-resolution. This will be useful in assessing possible volcanic features located on the dome. The resolution of HiRISE is particularly important along the southern flank of the dome, where one flow-like structure emerges. The HiRISE imagery will look for possible lava flow textures, as well as evaluate the flow-like structure's relationship with a fissure/crater near its source on the dome's flank.
Mound Cluster in Noachis Terra Degraded Crater - Request submitted: April 14, 2021; Request scheduled: February 17, 2022; Request fulfilled: February 22, 2022. This observation targets a cluster of mounds located in a 45 km degraded crater in Noachis Terra. These goal of this observation is to characterize the surface texture of the mounds, their stratigraphic relationship to the surrounding crater floor materials, and compare with other mound clusters found throughout the Noachian-aged highlands. The 1km crater at the southern end of the observation footprint may expose a contact between flat-laying crater floor materials and the mound materials. Faint banding is observed in the eastern crater wall in CTX imagery.
Light-Toned Sinuous Material (ESP_073040_1495) - Request submitted: July 31, 2019; Request scheduled: February 17, 2022; Request fulfilled: February 24, 2022. This observation targets three exposures of light-toned materials with a sinuous outcrop pattern visible in CTX image B19_017048_1504_XN_29S231W. These long, narrow outcrops appear to have formed parallel to the topographic gradient between degraded crater rim materials and a ridged plain surface. In addition, they may be related to other light-toned materials with sinuous outcrop patterns seen elsewhere in Terra Cimmeria (see HiRISE observation ESP_054748_1735). The small size of these outcrops (< 10 px at CTX resolution) precludes confident geomorphic analysis or assignment of stratigraphic position relative to the surrounding materials. Observations of these materials may aid in understanding the aqueous history of the western Terra Cimmeria region.
Resolution justification: This observation targets a small outcrop of material (< 50 m in width). Higher resolution will aid analysis of the surface properties of this material and better resolve the geologic contacts with the surrounding materials.
Intercrater Plain Thermophysical and Compositional Boundary (ESP_073725_1550) - Request submitted: October 30, 2020; Request scheduled: April 12, 2022; Request fulfilled: April 18, 2022. This observation targets a transitional zone at the boundary between high-thermal inertia intercrater plains materials and low thermal inertia highlands materials. In THEMIS 875 decorrelation stretch imagery, this region shows a sharp boundary between purple (ultramafic) and green/yellow (mafic to intermediate) units. The DCS purple unit appears to have lower crater retention than the DCS green/yellow unit. Similar contacts and mechanical contrasts are observed in other intercrater bedrock plains within the region. High-resolution imagery of this region will help interpret the causes for the differences between these two units.
Channel Crossing Heavily Eroded Wrinkle Ridge (ESP_073790_1485) - Request submitted: September 4, 2020; Request scheduled: April 19, 2022; Request fulfilled: April 24, 2022. This observation targets a channel crossing a heavily eroded wrinkle ridge. On the south side of the wrinkle ridge, a dark-toned channel is inset within a light-toned material. The light-toned material may be related to the channel, e.g. an overbank deposit or altered primary minerals related to the presence of groundwater. The small 1.5 km crater at the bottom left of the stamp appears to have a banded appearance in its upper rim. This observation will evalulate the relationship between these two materials, as well as evaluate the presence of layering in the light-toned materials. On the northern side of the wrinkle ridge, the channel has a ridge running down its center. It is unclear if this ridge is a clastic or volcanic fill deposit. The observation will observe the steep walls of this deposit and evaluate whether fine-scale layering consistent with a clastic deposit is present. Note: Stereo was not part of the initial request.
Light-Toned Materials at Highlands Valley Network Mouth (ESP_073927_1515) - Request submitted: August 23, 2019; Request scheduled: April 26, 2022; Request fulfilled: May 4, 2022. This observation targets a region of light-toned materials visible in CTX image B19_017236_1521_XN_27S324W. These materials are located within a geomorphically complex region at the mouth of a dendritic highlands valley network, and may represent a clastic deposit related to the valley network. This observation targets several particularly interesting landforms including: 1) an outcrop with tabular ledges (suggestive of layering), 2) a cluster of low, sinuous outcrops of darker-toned material (suggestive of topographically inverted channel deposits), and 3) a region of the light-toned material containing unusual ridges of unknown origin. HiRISE imaging resolution will help determine the presence of layering in this material, which may be useful for understanding the channel dynamics of the associated highlands valley network.
Mounds and Stratigraphy in Terra Cimmeria Crater (ESP_74279_1515) - Request submitted: May 20, 2021; Request scheduled: May 25, 2022; Request fulfilled: June 1, 2022. This observation explores the stratigraphy within a heavily degraded 25 km diameter crater in the Terra Cimmeria highlands. Several units are targeted. A mantling unit with potential periglacial features (low ridges with a shallow fissure along the crest) is exposed in the northern half of the crater. This unit covers possiblly layered bedrock which forms low ledges. Small exposures of light material are present in the bottoms of some small craters in the bedrock unit. This stratigraphy may be exposed in the rims of the 2 km crater at bottom center and the 1 km crater at center right. Finally, a mound-forming unit with an unclear relationship to the surrounding crater floor materials occurs in the northern half of the crater. In one mound, materials appear to be coarsely layered.
Large Dome on Crater Rim (ESP_074371_1555) - Request submitted: May 27, 2021; Request scheduled: May 26, 2022; Request fulfilled: June 8, 2022. This observation targets an approximately 4 km diameter dome located on the rim of a degraded 25 km crater. This dome may be a remnant of ejecta from a 10 km crater to the southeast. However, it does not have the texture of an ejecta deposit, and both craters do not appear to have surviving ejecta sheets outside the crate. In addition, in CTX image F01_036154_1562_XN_23S209W, a small amount of dome material appears to have flowed into the rim of the 10 km crater, suggesting that it postdates the formation of this crater. This image will study the relationship between the dome and both the 25 km and 10 km crater rims and be used to characterize the surface materials present on the dome.