Micro cold traps on the Moon

Hayne, P. O.; Aharonson, O.; Schörghofer, N.

doi:10.1038/s41550-020-1198-9

Cited by 84 publications

(81 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The area of seasonal cold traps implied from Williams et al (2019) is 17,500 km 2 for the north pole and 24,300 km 2 for the south. Hayne et al (2020) recently calculated the fractional area of cold traps at all size scales as a function of latitude. We used these three sets of values to modify the migration model from Kloos et al (2019), which was previously based on shadowing instead of temperature.…”

Section: Previous Estimates Of Water Ice Deliverymentioning

confidence: 99%

Stratigraphy of Ice and Ejecta Deposits at the Lunar Poles

Cannon

Deutsch

Head

et al. 2020

Geophysical Research Letters

View full text Add to dashboard Cite

Water ice has been delivered to the lunar poles from different sources over billions of years, but this accumulation was punctuated by large impacts that excavated dry regolith from depth and emplaced it in layers over the poles. Here, we model the resulting stratigraphies of ice and ejecta deposits in the lunar polar regions. Large polar craters were age dated, and their ejecta distributions calculated with standard scaling relations. We then created a Monte Carlo model for ice deposition and ejecta emplacement. Typical model runs showed that deposits in older cold traps (>4 Ga) are divided into two zones: buried ice-rich gigaton deposits and younger more gardened mantles. The latter are consistent with small crater morphometry measurements, but the existence of substantial ice buried at great depths is more difficult to confirm. Rare outlier model runs included Mercury-like cases with significant deposition events in recent history (<200 Ma). Plain Language Summary The polar regions of Earth's Moon have topographic depressions that are never directly exposed to the Sun, so they are cold enough for deposits of ice to exist. Water can get into these regions by water-bearing asteroids colliding with the Moon, or from lunar volcanoes erupting gases that travel to the poles. At the same time, large impact craters that form at the poles eject an enormous amount of soil and rock that could bury existing ice. It is not well understood how these two processes work together to build up deposits that may have alternating layers of ice-rich and ice-poor soil. In this study, we used computer simulations to predict what these layered deposits may look like. We found it is likely that large amounts of relatively pure ice are buried at depth in the oldest deposits, covered with thinner layers hosting less ice. Impact cratering has been the dominant process affecting the lunar poles, but the effects of large polar craters on nearby ice deposits have not been previously addressed. Impact effects have been considered for micrometeoroids (e.g.,

show abstract

Section: Previous Estimates Of Water Ice Deliverymentioning

confidence: 99%

Stratigraphy of Ice and Ejecta Deposits at the Lunar Poles

Cannon

Deutsch

Head

et al. 2020

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Determining the timing of water delivery to the Moon is a critical step in understanding the nature of the lunar volatile cycle and how it is evolving with time. The rough, ice-bearing craters identified here, as well as even smaller cold traps (Hayne et al, 2018;Rubanenko & Aharonson, 2017;Rubanenko et al, 2018), are excellent exploration candidates for studying the most recent history of volatile delivery to the Moon. Determining the abundance and precise chemical composition of volatiles within younger cold traps is essential in determining the recent fluxes and sources of volatiles to the lunar surface, providing insight into how the lunar volatile system is actively evolving.…”

Section: Discussionmentioning

confidence: 90%

Assessing the Roughness Properties of Circumpolar Lunar Craters: Implications for the Timing of Water‐Ice Delivery to the Moon

Deutsch

Head

Neumann

et al. 2020

Geophysical Research Letters

View full text Add to dashboard Cite

The roughness properties of impact craters are valuable indicators of crater degradation and can provide insight into crater ages. We evaluate the roughness of lunar craters from different geologic eras, confirming that young, Copernican craters are distinctly rougher than older craters. We evaluate the potential age of small (less than ~15 km) craters that are thought to host surface ice by quantifying the roughness inside these craters, as well as outside. Interior roughness may be subdued by slope processes or the presence of volatiles. The distribution of ice‐bearing craters is skewed toward roughness values higher than those of pre‐Imbrian craters, although no ice‐bearing craters are within the Copernican‐only domain in roughness space. All of the 15 rough, permanently shadowed craters that are found within the Copernican‐only domain lack water‐ice detections, suggesting that either ice has not been delivered to these young craters or that it has since been destroyed.

show abstract

“…At the crater rim temperature drops lower than on the steep crater walls since the solar incidence angle is basically perpendicular which leaves small craters in permanent shadow acting as so‐called micro cold traps. Micro cold traps are commonly referred to as PSRs in craters on scales of <100 m which make up the significant part of 10% of the area of all lunar PSRs (Hayne et al., 2020). Additionally, it is here on Shackleton's rim where we generally also find locations with extended and continuous periods of illumination offering the possibility to charge batteries of rovers and landers relying on solar panels (Gläser et al., 2014, 2018).…”

Section: Resultsmentioning

confidence: 99%

Temperatures Near the Lunar Poles and Their Correlation With Hydrogen Predicted by LEND

et al. 2021

View full text Add to dashboard Cite

The lunar polar regions offer permanently shadowed regions (PSRs) representing the only regions which are cold enough for water ice to accumulate on the surface. The Lunar Exploration Neutron Detector (LEND) aboard the Lunar Reconnaissance Orbiter (LRO) has mapped the polar regions for their hydrogen abundance which possibly resides there in the form of water ice. Neutron Suppression Regions (NSRs) are regions of excessive hydrogen concentrations and were previously identified using LEND data. At each pole we applied thermal modeling to three NSRs and one unclassified region to evaluate the correlation between hydrogen concentrations and temperatures. Our thermal model delivers temperature estimates for the surface and for 29 layers in the sub-surface down to 2 m depth. We compared our temperature maps at each layer to LEND neutron suppression maps to reveal the range of depths at which both maps correlate best. As anticipated, we find the three south polar NSRs which are coincident with PSRs in agreement with respective (near-)surface temperatures that support the accumulation of water ice. Water ice is suspected to be present in the upper ≈ 19 cm layer of regolith. The three north polar NSRs however lie in non-PSR areas and are counter-intuitive as such that most surfaces reach temperatures that are too high for water ice to exist. However, we find that temperatures are cold enough in the shallow sub-surface and suggest water ice to be present at depths down to ≈ 35 − 65 cm. Additionally we find ideal conditions for ice pumping into the sub-surface at the north polar NSRs. The reported depths are observable by LEND and can, at least in part, explain the existence and shape of the observed hydrogen signal. Although we can substantiate the anticipated correlation between hydrogen abundance and temperature the converse argument cannot be made.

show abstract

Micro cold traps on the Moon

Cited by 84 publications

References 39 publications

Stratigraphy of Ice and Ejecta Deposits at the Lunar Poles

Stratigraphy of Ice and Ejecta Deposits at the Lunar Poles

Assessing the Roughness Properties of Circumpolar Lunar Craters: Implications for the Timing of Water‐Ice Delivery to the Moon

Temperatures Near the Lunar Poles and Their Correlation With Hydrogen Predicted by LEND

Contact Info

Product

Resources

About