NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, permafrost, ice, ground penetrating radar, Mars

Objective(s): To investigate icy Arctic scarps as analogues for ice-exposing scarps on Mars.

Project Description: This licence has been issued for the scientific research application No.5390. The research team propose investigating icy Arctic scarps as analogues for ice-exposing scarps on Mars. Scarp-side exposures of massive tabular ice, overlain by a polygonized overburden dotted with thermokarstic depressions, occur in the continuous and extremely deep permafrost of the Tuktoyaktuk Coastlands in the Canadian arctic and in the eastern Russian arctic. An important example of these exposures is near Tuktoyaktuk (133°02 ' W; 69°26 ' N). These are meters- to decameters-deep massive tabular ice-deposits that formed in the mid- to late-Wisconsonian Epoch. Their distribution is wide-ranging and they are markers of a post-glacial climate that differed substantially from today. Hypotheses explaining the origin of the tabular massive-ice in the Canadian and Russian Arctic are varied and include: a) Iterative permafrost aggradation and the formation of post-glacial segregation ice by the injection of meltwater into freezing sediments; b) regelation at the base of a glacier, where increased pressure and decreased pressure melting point across an obstacle leads to melting on the up-glacier side of the obstacle and refreezing in the low-pressure lee-side, which over time can form layers of basal ice; and, c) post-glacial burial and preservation of glacier-ice within permafrost. Near to our proposed field site, accessible scarps expose ice with different preferred origins (periglacial and glacial). A community-wide goal in Mars science is to “understand the processes and history of climate on Mars”. The research team proposed work would be an advance because the origin of mid-latitude tabular massive ice and the development of the ice overburden depend on past climate conditions and surface processes. Studying ice-exposing scarps improves our understanding of how ice is emplaced on Mars, which provides a constraint for Mars’ climate models and a constraint on remote sensing characteristics that are used to map the distribution of near-surface ice on Mars. The work is timely because the International Mars Ice Mapper Mission that would use satellite-based radar to map the extent and volume of non-polar ice deposits could launch as soon as 2026. And, strategic scientific planning is ongoing. The proposed findings and data sets would add to the current state-of-knowledge about the Arctic icy scarps themselves and open an analogical pathway for critically comparing and contrasting the Earth and Mars based landforms. From the early days of the Mariner missions to Mars, possible Earth geomorphological and geological analogues have been used to evaluate observed similarities of form, size and spatial association with Martian landscape features and landforms. The main objective of this work is to supplement and enhance this decades-long work, but with a specific lens on the recently observed icy scarps on Mars. The photo-geological data sets will be collected at a distance that resolves scarp-face structure comparable to high-resolution imagery as well as from a closer distance to evaluate how structural information may be resolution-limited in Mars’ data. By combining image-based and radar-based views of the icy scarps, the team will generate a novel 3-D view of these terrains. In addition to the value of this work for planetary sciences, the research team will make available new data sets of these rapidly degrading coastal ice exposures, which are relevant to understanding the origin hypotheses of this ice and will contribute to work done by others who monitor and evaluate ice stability and how that impacts the Tuktoyaktuk community. The fieldwork focuses on the Tuktoyaktuk Coastlands, and specifically at the area of Peninsula Point, southwest of the village of Tuktoyaktuk. In this area the research team can access scarps that expose ice with different preferred origins (periglacial and glacial). While the exact locations of scarp sites in this area with a likely glacial origin are not documented precisely in the literature, the team would rely on local knowledge and work with local guides to identify these locations based on available descriptions; scarp sites with a likely periglacial origin are known. The team plan to arrive in the field just after the sea ice clears from the coast. As possible during the days in Tuktoyaktuk the team would be transported to Peninsula Point by boat, as the field sites are not accessible by land. Transportation one-way can take up to one hour and the team can work at the remote sites for 8-10 hours per day. As needed to accomplish the goals the team can work in groups of two or three, or together as a whole team. In order to generate a 3-D view of the Arctic icy scarps the research team will conduct photogeologic, photogrammetric, and ground-penetrating radar surveys. Structure visible in the scarp exposure will be tied-in with internal structure observed in the radargrams to add a new dimension of information. Photogeologic surveys: At least two scarp-face sections, one of them thought to be periglacial and the other glacial in origin, will be photographed cross-sectionally and planimetrically with a digital camera, and then mapped. Detailed field notes will complement the photographs. UW Earth and Space Sciences owns suitable cameras and lenses that can be borrowed and can be integrated with a high-precision GPS on a tripod. The mapping process will include 1) identifying if exposures exhibit layers, ice wedges, boulder inclusions, or other structures in the ice; 2) photographing portions of the scarp face at deliberate distances so that structures are visible at a scale comparable to HiRISE imagery (25 cm/pixel), or better; and, 3) organizing detailed field notes and measurements of the scarp face including estimations of the fine-scale layering, as well as overburden thickness, polygonization of the overburden surface, and forefield conditions. Photogrammetric surveys: Additionally, a large number of images taken from multiple view-angles of the target scarp faces (>500 per scarp) will be collected by drone (if approved) and/or on foot with a digital camera. From these data the team will use Structure from Motion (SfM) photogrammetry software to generate 3-D point clouds of elevation. A distributed network of 30-50 ground-control points—whose location is to be measured in the field a priori using high accuracy GPS—will allow output point clouds to be geo-rectified and for images and photogeological maps of scarp structure to, in turn, be projected onto the resulting 3-D representation of scarp geometry. This provides an effective way to robustly tie the location and mapped characteristics of structures seen in the scarp face imagery with those measured using radar. Ground-penetrating radar surveys: Radar data will be collected using a commercial radar system mounted on a roller sled pulled by an operator traveling on foot. This is a common practice on rocky or hummocky terrains. The penetration depth and fidelity of radar data depends on the specific frequency of operation and substrate conditions. The PI and graduate student would test the system prior to fieldwork and together with Collaborator Adam Hepburn the team would choose a series of appropriate radar-frequencies, taking into account site conditions. The research team anticipate using several frequencies from 100 to 500 MHz to fully capture the depth distribution and internal structure of the buried ice inland of the scarp exposures. The radar will be run along the top of the icy exposures, traveling inland from, and perpendicular to, the mapped scarp faces at a grid spacing dictated by radar frequency. A high-precision differential GPS system will be used to enable the sub-centimeter topographic correction of the output radar transects to account for uneven terrain and to allow these transects to be geo-rectified and correlated in 3-D space. Further, this will allow the radar data to be accurately compared to the models of the scarp exposure generated using photogrammetry. Contact will be made with community leaders in Tuktoyaktuk (Inuvialuit Land Administration) and Inuvik (Hunters and Trappers Association). If possible, meetings will be held in Inuvik and Tuktoyaktuk to elaborate on the plans The fieldwork for this study will be conducted from April 26, 2023 to June 26, 2023.