Mars, Ceres, and the Earth have abundant reserves of ground ice. On Earth, ice-cored mounds known as pingos (Fig. 1) are important indicators of extant and extinct near-surface groundwater systems, hydrogeologic properties, and local climate. Spacecraft observations of Mars and Ceres have revealed a variety of deca- to kilometer scale hills with morphological similarities to terrestrial pingos in ice-rich environments (Fig. 2)[2,3,4,5,6]. Domes observed on Europa, Ganymede, and Callisto also resemble these ice-cored structures[7,8,9]. These potential hydrologically controlled pingo-like features (PLFs) represent unique science targets that may contain information regarding groundwater history, hydrologic properties, and habitability due to their formation by liquid water. For these reasons, identifying, characterizing, and determining the origin of possible PLFs on Mars and Ceres are high priority science objectives related to the history of water in the solar system. They also represent potential resource deposits for future explorers. The difficulty in characterizing potential PLFs and their formation processes on Mars and Ceres is their small size and the buried nature of any supporting ice structure.
Pingo STARR will advance human and lander scale geophysical techniques specifically tailored to detect, characterize, and investigate the cryohydrology and genesis of possible PLFs on Earth, Mars, and Ceres. This systems-level field campaign will be the most comprehensive to date for any terrestrial pingos, and the first dedicated analysis of pingos from a planetary science perspective. Our science and technology objectives will provide valuable insight into detecting and characterizing ground -ice and -water systems on Mars and Ceres.
To understand PLFs and prepare for their direct exploration, we turn to pingos in the North American Arctic. Despite the existence of ~11,000 pingos on Earth, only a handful have been studied for prolonged durations, and few have been surveyed using geophysical methods[11,12,13,14]. We will investigate the predominantly unexplored subsurface structures of some of the largest hydrostatic pingos on Earth in the North American Arctic. This field program seeks to identify the connections between the structural elements of pingos, their overlying morphology, and their underlying hydrology; and characterize a pingo ‘lifecycle’ as a process analog for past and present PLF generating hydrologic systems on Mars and Ceres by acquiring an unprecedentedly thorough and detailed geophysical data set.
Figure 1. (a) Oblique view of the ~50 m tall Ibyuk Pingo, Tuktoyaktuk, Northwest Territories, Canada (image credit - CBC). (b) Plan view look at Ibyuk Pingo (image credit - Google Earth). (c) Pingo candidate on Mars (image citation HiRISE image - PSP_007533_1420, Planetary Data System). (d) Two pingo candidates on Ceres (Dawn framing camera image - FC21A0095112_18186151802F1A, Planetary Data System).
We will investigate pingo systems by:
1) characterizing their internal ice structure and hydrologic systems using geophysical methods;
2) capturing the full ‘lifecycle’ of pingos by analyzing them at various stages of degradation and characterizing the evolution of their hydrological systems; and
3) constraining relevant formation conditions, properties, and processes that would be required to form potential PLFs on other planets through direct comparisons of these features with terrestrial pingos in the context of their internal ice and groundwater distributions.
Our technology objectives are to:
1) evaluate and optimize lander and human-scale ground penetrating radar (GPR), time domain electromagnetic (TEM), and capacitively-coupled resistivity (CCR) systems for the detection of pingo ice and unfrozen water layers in the subsurface via vertical sounding, 2D profiling, and 3D surveying;
2) identify and evaluate the capabilities and limitations of the chosen geophysical methods for pingo surveys in an analog environment; and
3) identify and evaluate synergies that exist between GPR, CCR, and TEM for detecting and characterizing pingo systems.
Figure 2. Comparison of a possible pingo candidate on Ceres (a: Dawn framing camera image - FC21A0095112 _18186151802F1A, Planetary Data System) with Ibyuk Pingo (b: Sentinel image - T08WNC_20181001T210301, Copernicus Open Access Hub). While the cerean mound is nearly twice as large in every dimension, their forms are similar (c). Profiles were derived from Dawn stereo pairs and the ArcticDEM (Porter et al., 2018). Adapted from Schmidt et al., In Press.
Pingo STARR is a four-year (2020-2024) field campaign funded through NASA's Planetary Science and Technology through Analog Research (PSTAR) program.
1 Mackay, J. R., (1998). Pingo growth and collapse, Tuktoyaktuk Peninsula area, Western Arctic Coast, Canada: a long-term field study. Géographie physique et Quaternaire, 52: 271-323. https://doi.org/10.7202/004847ar
2 Dundas, C. M., and McEwen, A. S., (2010). An assessment of evidence for pingos on Mars using HiRISE. Icarus 205, 244-258. https://doi.org/10.1016/j.icarus.2009.02.020
3 Sizemore, H. G., and 29 co-authors, (2019a). A global inventory of ice-related morphological features on dwarf planet Ceres: Implications for the evolution and current state of the cryosphere. J. Geophys. Res. Planets, 124. https://doi.org/10.1029/2018JE005699
4 Sizemore, H. G., B. E. Schmidt, and J. C. Castillo-Rogez, (2019b). Introduction to the Special Issue: Ice on Ceres. JGR-Planets, 124. https://doi.org/10.1029/2019JE006012
5 Hughson, K. H. G., Schmidt, B. E., Sizemore, H. G., Scully, J. E. C., Duarte, K., Romero, V. N., Schenk, P. M., Buczkowski, D. L., Williams, D. A., Nathues, A., Castillo-Rogez, J. C., Raymond, C. A., Russell, C. T., (2019). Frost heaves may exist in Occator crater, Ceres. Geological Society of America Annual Meeting, Phoenix, AZ. Abs. #144-6.
6 Schmidt, B. E., Sizemore, H. G., Hughson, K. H. G., Duarte, K. D., Romero, V. N., Scully, J. E. C., Schenk, P. M., Buczkowski, D. L., Williams, D. A., Nathues, A., Udell, K., Castillo-Rogez, J. C., Raymond, C. A., Russell, C. T., (In Press). Hydrological evolution of Occator crater: Implications from pingo and frost heave morphology. Nature Geoscience.
7 Schenk, P. M., (1993). Central pit and dome craters: Exposing the interiors of Ganymede and Callisto. J. Geophys. Res., 98(E4), 7475– 7498. https://doi.org/10.1029/93JE00176
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9 Squyre, S. W., (1980). Topographic domes on Ganymede: Ice vulcanism or isostatic upwarping. Icarus 44, 472-480. https://doi.org/10.1016/0019-1035(80)90038-X
10 Grosse, G. and Jones, B. M., (2011). Spatial distribution of pingos in northern Asia. The Cryosphere 5, 13-33. https://doi.org/10.5194/tc-5-13-2011
11 Angelopoulos, M. C., Pollard, W. H., Couture, N. J., (2013). The application of CCR and GPR to characterize ground ice conditions at Parson Lake, Northwest Territories. Cold Regions Science and Technology 85. 22-33. https://doi.org/10.1016/j.coldregions.2012.07.005
12 Arcone, S. A., Belaney, A. J., Sellmann, P. V., (1979). Effects of seasonal changes and ground ice on electromagnetic survey of permafrost. Hanover, New Hampshire: United States Army Corps of Engineers, CRREL Report, 79-23.
13 Ross, N., Harris., C., Christiansen, H. H., Brabham, P. J., (2007). Ground penetrating radar investigations of open system pingos, Adventdalen, Svalbard. Norwegian Journal of Geogrphy 59:2, 129-138. https://doi.org/10.1080/00291950510020600
14 Yoshikawa, K., Leuschen, C., Ikeda, A., Harada, K., Gogineni, P., Hoekstra, P., Hinzman, L., Sawada, Y., and Matsuoka, N., (2006). Comparison of geophysical investigations for detection of massive ground ice (pingo ice), J. Geophys. Res., 111, E06S19. https://doi.org/10.1029/2005JE002573
©2020 by Kynan H. G. Hughson.