Inverted Crater with Concentric Ridges (ESP_056571_1555) - Request submitted: November 11, 2016; Request scheduled: July 4, 2018; Request fufilled: August 21, 2018 (failed attempt on July 9 due to global dust storm). Inverted crater located within a bedrock window that appears to preserve material from surrounding mesas. These mesas appear to be a part of a resistant regional unit that commonly produces inverted terrain. The inverted crater is unusual in that it has at least two concentric ridges. The primary goal of this HiRise observation is to help understand the formation process behind these ridges. The secondary goal is to understand the relationship between the resistant unit and the underlying unit.
Sinuous Ridge with Anastamosing Morphology (ESP_056676_1590) - Request submitted: September 13, 2017; Request scheduled: August 22, 2018; Request fulfilled: August 29, 2018. This observation targets a small (>100m) sinuous ridge visible in CTX image F04_037463_1578_XN_22S307W. This ridge appears to have an anastamosing morphology, while short segments appear to have a central trough. These textures suggest that this unit is an inverted channel-like feature. The ridge also appears to grade into a high thermal inertia surface at the bottom of this image. This observation serves two purposes. It will a) clarify the morphology of the sinuous ridge to help understand its origin and b) aid in determining any possible relationship between the ridge and high thermal inertia surface.
Mound Feature in Terra Sabaea Intercrater Plain (ESP_057455_1520) - Request submitted: August 16, 2018; Request scheduled: October 23, 2018; Request fulfilled: October 29, 2018.This observation targets a mound located within a Noachian intercrater bedrock plain. The mound exhibits potential layering along its eastern edge in CTX image D20_035143_1524_XN_27S328W. This mesa may be a portion of a stratigraphic sequence within the intercrater bedrock plain; layering within bedrock plain materials is visible in HiRISE image ESP_044242_1520. This observation will observe the stratigraphic relationship between the mound and surrounding plains. Determining whether this mound is a portion of the bedrock plain stratigraphy will aid in understanding lithification processes in this plain, as these materials may be an erosional remnant of former overburden throughout the intercrater plain.
Knobs associated with Dike Feature (ESP_057691_1710) - Request submitted: August 16, 2018; Request scheduled: November 7, 2018; Request fulfilled: November 16, 2018. This observation targets a knob field associated with a large Hellas-Huygens system dike. It is unclear whether the knob field is an intrusion potentially related to this dike system, or if the dike system superposes it. The dike and knob cluster are tonally similar in CTX imagery, but HiRISE multispectral imaging could help confirm this link. Alternatively, the knob field or dike may be stratigraphically superposed on the other, in which case high resolution imagery will help determine the sequence of formation of these units.
Possible Banded Olivine-Rich Massif in Northeast Hellas Planitia (ESP_058944_1540) - Request submitted: December 5, 2018; Request scheduled: February 11, 2019; Request fulfilled: February 22, 2019. 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. Coarse, 100 m scale banding is visible in an apparent megabreccia block at this location in CTX image B19_017090_1515_XN_28S298W. High-resolution imagery of this block will be useful to evaluate differences in banding across this outcrop, as well as assess whether finer-scale banding not visible at CTX resolution is present.
Mesa in Terra Sabaea Bedrock (ESP_059429_1680) - Request submitted: August 17, 2018; Request scheduled: March 27, 2019; Request fulfilled: April 1, 2019. This observation targets a mesa located within a Terra Cimmeria bedrock plain. This feature is largely unique within this plain, with the exception of a single (potentially-related) counterpart about 15 km to the south. The formation mechanism of this feature is unknown. It may be an erosional remnant of a sedimentary deposit, as faint tonal banding is partially visible in the mesa walls and in the walls of a 1 km crater that has impacted into the mesa. This observation will help confirm the presence of tonal banding. It also images a small portion of the surrounding bedrock plain to help understand the stratigraphic relationship between these materials and the mesa. The textural properties observed by HiRISE will also help determine the lithological and mechanical behavior of mesa materials.