Thick ice deposits in shallow simple craters on the Moon and Mercury

Rubanenko, Lior; Venkatraman, Jaahnavee; Paige, D. A.

doi:10.1038/s41561-019-0405-8

Cited by 94 publications

(61 citation statements)

References 37 publications

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“…The potential volume of the micro cold traps is even smaller, scaling as ~D 3 , and we find that those with D < 1 m could account for ~10 −5 of the total cold-trapping volume, despite being vastly more numerous than larger cold traps. Thus, the potential presence of ice deposits tens of metres thick in the Moon's south polar region 35 is consistent with our finding that large >1-km-scale cold traps are more prevalent in the south than the north, dominating the cold-trapping volume.…”

Section: Calculation Of Shadow Temperaturessupporting

confidence: 91%

Micro cold traps on the Moon

2020

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Water ice is thought to be trapped in large permanently shadowed regions in the Moon's polar regions, due to their extremely low temperatures. Here, we show that many unmapped cold traps exist on small spatial scales, substantially augmenting the areas where ice may accumulate. Using theoretical models and data from the Lunar Reconnaissance Orbiter, we estimate the contribution of shadows on scales from 1 km to 1 cm, the smallest distance over which we find cold-trapping to be effective for water ice. Approximately 10-20% of the permanent cold-trap area for water is found to be contained in these micro cold traps, which are the most numerous cold traps on the Moon. Consideration of all spatial scales therefore substantially increases the number of cold traps over previous estimates, for a total area of ~40,000 km 2 , about 60% of which is in the south. A majority of cold traps for water ice is found at latitudes > 80° because permanent shadows equatorward of 80° are typically too warm to support ice accumulation. Our results suggest that water trapped at the lunar poles may be more widely distributed and accessible as a resource for future missions than previously thought.

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Section: Calculation Of Shadow Temperaturessupporting

confidence: 91%

Micro cold traps on the Moon

2020

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“…If instead of extensive Mercury‐like surface deposits, ancient lunar ice was buried under meters of regolith (e.g., Rubanenko et al, ), and if cohesive ice deposits exist at depths between 1 and 10 m, the surface ice we observe may be the result of secondary impact gardening up‐sampling that ice during the Copernican era. Our gardening calculations at high probability give a lower limit on the depth of up‐sampled ice.…”

Section: Discussionmentioning

confidence: 89%

“…At the surface, evidence of patchy surface water that covers roughly 10% of the total PSR area has been presented by workers using LRO Lunar Orbiter Laser Altimeter reflectance measurements, LRO Lyman Alpha Mapping Project UV spectra, and Chandrayan Moon Mineral Mapper infrared spectra, coupled with temperature data from the LRO Diviner thermal radiometer (e.g., Fisher et al, ; Hayne et al, ; Li et al, ; Milliken & Li, ; Zuber et al, ). A statistical approach by Rubanenko et al () concluded that craters in the south lunar polar region have relatively low depth‐diameter ratios and suggested that the shallowing is caused by buried ice; however, because of the statistical nature of the work, they could not identify individual shallowed candidate carters, and the mystery of why there might be an asymmetric distribution of water by any source between the north and south poles remains a mystery and concern. While the Moon's poles are not completely dry, the limited distribution and quantity of water ice are in stark contrast with Mercury's extensive icy deposits.…”

Section: Introductionmentioning

confidence: 99%

Impact Gardening as a Constraint on the Age, Source, and Evolution of Ice on Mercury and the Moon

et al. 2020

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We update an analytic impact gardening model (Costello et al., 2018, https://doi.org/10.1016/j.icarus.2018.05.023) to calculate the depth gardened by impactors on the Moon and Mercury and assess the implications of our results for the age, extent, and source of water ice deposits on both planetary bodies. We show that if the water presently on the Moon has a primordial origin, it may have been 4–15 m thick. If ice deposits are buried, they may be as shallow as 3 cm or as deep as 10 m and provide a gradient of probability for ice gardened into a column. Our calculations for gardening on Mercury show that thermal lag deposits will be reworked into the background over 200 Myr, and, thus, the most recent large‐scale deposition of ice on Mercury must have occurred no more than 200 Myr ago. We also find that gardening mixes incremental layers of ice with underlying regolith and prevents the growth of pure ice deposits by continuous supply. We conclude that ice deposits on the Moon and Mercury are likely the result of sudden and voluminous deposition.

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“…A few studies have applied techniques from geomorphic analysis to address the question of lunar ice (Deutsch et al., 2020; Rubanenko et al., 2019). On Earth and other solar system bodies, quantitative landform analysis has proven valuable for identifying the presence of near‐surface ice deposits or ice‐rich surface materials (Boeckli et al., 2012; Kreslavsky & Head, 2000; Mangold, 2003; Mahaney et al., 2007; Rossbacher & Judson, 1981).…”

Section: Introductionmentioning

confidence: 99%