Mercury's Polar Caps and the Generation of an OH Exosphere☆

Killen, R. M.; Benkhoff, J.; Morgan, T. H.

doi:10.1006/icar.1996.5601

Cited by 57 publications

(74 citation statements)

References 51 publications

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“…Thermal models show that in permanently shadowed regions of high-latitude craters, water ice covered by a regolith layer can be stable to evaporation over billions of years (Paige et al 1992;Vasavada et al 1999). The ice is thought to have been implanted by either constant micrometeoritic, asteroidal and cometary influx (Killen et al 1997), or to stem from a few large impacts by comets and/or asteroids (Moses et al 1999;Barlow et al 1999). The MESSENGER spacecraft observed areas of high and low near-infrared (NIR) reflectivity, which is interpreted as surface ice and ice buried under a layer of organic material Paige et al 2013).…”

Section: Water In the Planetsmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

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Section: Water In the Planetsmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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“…Potter [1995] proposed that the distribution of Na on Mercury and the Moon is consistent with a chemical sputtering source. In addition to the meteoritic source for water on Mercury considered by Killen et al [1997a], there may be a chemical source [Potter, 1995]. Potter [1995] showed that water is an inevitable by-product of sodium production by chemical sputtering, and he argued that the temperatures at Mercury's surface are optimum for these reactions to proceed.…”

Section: 3 / Reviews Of Geophysicsmentioning

confidence: 99%

The surface‐bounded atmospheres of Mercury and the Moon

Killen¹,

Ip²

1999

Reviews of Geophysics

171

123

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Abstract. Surface-bounded exospheres have been detected at the Moon, Mercury, and Europa and almost certainly exist about other objects. Historically, the first of these systems to be observed was the lunar exosphere, where He and Ar were detected by the Apollo spacecraft. The Hermean exosphere is archetypical of these systems in that it is part of a coupled system including the surface and magnetosphere interacting dynamically with the solar wind and fields. Studies of the Hermean exosphere heretofore have neglected or only superficially considered these interactions. We will review the current state of knowledge of the exospheres of Mercury and the Moon and discuss areas in which our knowledge is most incomplete. We will focus on the exosphere as part of a coupled system including the surface at its base and the particle, field, and interplanetary environment as both a source and sink for neutrals. Apollo era instruments made unambiguous detections of 36mr, 4ømr, Early Work and OverviewIn a review prior to the Mariner 10 encounter, Banks et al. [1970] reported no observational evidence for the presence of an atmosphere about Mercury. They predicted an exosphere (N < 2 x 10 TM cm -2) or thin atmosphere resulting from diffusion or effusion from the interior, solar wind implantation with subsequent thermal evaporation, or sputtering. By scaling terrestrial noble gas production and diffusion rates and assuming a lunar-like solar wind interaction, they suggested that the most abundant constituents should be the noble gases derived from the solar wind and radiogenic sources, the most abundant being 4He, followed by 4øAr and 2øNe.

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“…In the past, the stability of polar deposits has been compared with extrapolations of the evaporation rate of crystalline ice (Watson et al 1961b, Ingersoll et al 1992, Vasavada et al 1999. It has been recognized that water vapor condensing at low temperatures on planetary and cometary bodies may condense in the form of ASW rather than crystalline ice (Kouchi 1987, Killen et al 1997. Anderson et al (1978) concluded that on Mars the first one or two adsorbed layers will exist in the amorphous state and that additional layers would show the crystallography of ice.…”

Section: Damp Dust: Adsorption and Lunar Water Retentionmentioning

confidence: 98%