Near-Surface Temperatures on Mercury and the Moon and the Stability of Polar Ice Deposits

Evidence for water ice on the Moon: Results for anomalous polar craters from the LRO Mini‐RF imaging radar

“…Abundant secondary craters from the Orientale basin cover the south polar area [Spudis et al, 2009]. Both polar regions contain large amounts of permanently shadowed terrain, thought on the basis of theory to be very cold (less than 100 K) [Vasavada et al, 1999;Paige et al, 2010a] and subsequently shown from Diviner data to be as cold as 25 K in some areas [Paige et al, 2010b] and thus, are located where water ice might be stable for geologically long periods of time (>1 Ga) [Vasavada et al, 1999].…”

“…These two factors result in large areas (more than 30,000 km 2 at both poles) [McGovern et al, 2013] that remain in permanent darkness and are thus very cold [Vasavada et al, 1999;Paige et al, 2010b]. Images from the Clementine global mapping mission revealed large areas of darkness near the south pole of the Moon [Shoemaker et al, 1994].…”

Depth of faulting and ancient heat flows in the Kuiper region of Mercury from lobate scarp topography

“…The depth of faulting obtained for three different regions of Mercury by Watters et al (2002), Ritzer et al (2010) Vasavada et al (1999), which results in lateral BDT depth variations. Details of the model can be found by Williams et al (2007Williams et al ( , 2011 and references therein.…”

“…The distribution of surface temperatures on Mercury is heterogeneous primarily due to the coupled spin-orbit resonance and relatively high eccentricity ( � 0.2) resulting in a strong longitudinal and latitu dinal dependence on insolation (see Mitchell and de Pater, 1994;Vasavada et al, 1999;Aharonson et al, 2004). We take into account this effect by assuming a surface temperature of 435 K, a value representative for the location of the three scarps studied here after the present -day surface temperature model of Vasavada et al (1999), Heat flow for the Kuiper and the Discovery Rupes regions calculated after the thermal history model methodology described by Williams et al (2011) for several composition models for Mercury (see Hauck et aI., 2004). Hauck et al (2004) for details on heat-producing elements abundances in compositional models) are between 16 and 29 mW m-2 when usual crustal enrichment factors of 1-4 are applied (see Williams et al, 2011).…”

Water detection on atmosphereless celestial bodies: Alternative explanations of the observations

“…The incident radar waves were supposed to be scattered predominantly in the subsurface regolith layers with constant temperature. This temperature is -300-450 K at low latitudes, 200-220 K in polar regions, and 50-80 K in permanently shadowed craters; in the largest Mercury polar crater X a temperature less than 50 K was predicted [Vasavada et al, 1999]. As shown in section 5.3, dielectric losses at these temperatures may be low enough for high radar brightness and depolarization ratio.…”