82-2 Investigating Liquid Water and Microbial Lifeforms in the Variably Frozen Great Kobuk Sand Dunes: An Earth Analog for Sand Dunes at the Surface of Icy Ocean Worlds

Session: Friends of Hoth, Episode IX: The Rise of Icy Ocean Worlds

Presenting Author:

Cynthia Dinwiddie

Authors:

Dinwiddie, Cynthia L.¹, Phillips-Lander, Charity M.², Stillman, David E.³, Radebaugh, Jani⁴, Kantner, Seth⁵, Henderson, W. Patrick⁶, Baginski, Emma⁷, Wendt, David R.⁸, Flores, Mauricio E.⁹, Parmenter, Dylan S.¹⁰, Oladeji, Emmanuel O.¹¹, Atekwana, Estella A.¹²

(1) Space Science Division, Southwest Research Institute, San Antonio, TX, USA, (2) Space Science Division, Southwest Research Institute, San Antonio, Texas, USA, (3) Solar System Science and Exploration, Southwest Research Institute, Boulder, CO, USA, (4) Geological Sciences, Brigham Young University, Provo, Utah, USA, (5) Self-employed, Kotzebue, Alaska, USA, (6) Self-employed, Anchorage, Alaska, USA, (7) Geological Sciences, Brigham Young University, Provo, Utah, USA, (8) Space Science Division, Southwest Research Institute, San Antonio, Texas, USA, (9) Space Science Division, Southwest Research Institute, San Antonio, Texas, USA, (10) Chemistry and Chemical Engineering Division, Southwest Research Institute, San Antonio, Texas, USA, (11) Department of Earth and Planetary Sciences, University of California, Davis, Davis, California, USA, (12) College of Letters and Science, Department of Earth and Planetary Sciences, University of California, Davis, Davis, California, USA,

Abstract:

Sand dunes composed of sand-sized particles are found on Earth, Mars, Saturn’s moon Titan, and other icy ocean worlds. Generally, liquid drains quickly through sand. However, in March 2010, ground-penetrating radar (GPR) and electrical resistivity data revealed near-surface liquid water high in Alaska’s frozen Great Kobuk Sand Dunes (GKSD). This water was found below a 2-to-4 m-thick seasonally frozen layer and above the regional water table at interdune elevation. Cryohydrologic simulations suggested it is perched on an ice lens above dry permafrost, forming and thawing with slow dune migration. The year-round presence of liquid water may create an oasis for microbial life and biosignature preservation.

The ARRAKIS project (Assessing Regional Reflectors of Astrobiology in Kobuk Dunes for Interplanetary Science), supported by NASA, surveyed GKSD in March and September 2025. Our goals are to determine if life exists in nutrient-poor, wet sands, detect signs of life with planetary-mission-analog instruments, and understand how seasonal changes affect the cryohydrologic system and microbial activity. The research focused on a large sand dune and adjacent interdune areas, likely more hospitable due to groundwater’s presence.

In March, the GKSD were covered with snow with near-surface temperatures of -23°C. Snowmobile-enabled long geophysical surveys using 100–250 MHz GPR antennas and a capacitively coupled resistivity instrument produced data across dune crest, its stoss slopes, and interdunes. We also collected spectral induced polarization data near drillholes and in September, added induced polarization data near drillholes.

Drilling into the interdune reached 2.63 m, revealing liquid water at and below 2.5 m. Drilling on the dune’s stoss slope reached 4.55 m, revealing a dry interval from 2.8 to 3.5 m, with variably frozen to semisaturated sand below, transitioning to dry sand at 4.55 m. Sand collected downhole at 10 cm intervals was measured for microbial activity (ATP bioluminescence), biopolymers (total DNA), cell counts, chemical biosignatures (GC-MS), and habitability factors (moisture content, mineralogy, water chemistry, grain size). The highest microbial activity was found in the top 50 cm and at 250 cm below interdune, with lower activity in dune samples.

We present new geophysical and astrobiological data and interpretations of the cryosphere’s moisture and microbial activity distributions to enhance understanding of how liquid zones in cold-climate dunes might create and preserve habitable environments, guiding future exploration of similar environments on other planetary bodies.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10722

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