Radar images have revealed the possible presence of ice deposits in
Mercury's polar regions. Although thermal models indicate that watts
ice can be stable in permanently shaded regions near Mercury's poles,
the ultimate source of the water remains unclear. We use stochastic
models and other theoretical methods to investigate the role of external
sources in supplying Mercury with the requisite amount of water.
By extrapolating the current terrestrial influx of interplanetary
dust particles to that at Mercury, we find that continual micrometeoritic
bombardment of Mercury over the last 3.5 byr could have resulted
in the delivery of (3-60) x 10(16) g of water ice to tb permanently
shaded regions at Mercury's poles (equivalent to an average ice thickness
of 0.8-20 m), Erosion by micrometeoritic impact on exposed ice deposits
could reduce the above value by about a half. For comparison, the
current ice deposits on Mercury are believed to be somewhere between
similar to 2 and 20 m thick. Using a Monte Carlo model to simulate
the impact history of Mercury, we find that asteroids and comets
can also deliver an amount of water consistent with the observations.
Impacts from Jupiter-family comets over the last 3.5 billion years
can supply (0.1-200) x 10(16) g of water to Mercury's polar regions
(corresponding to ice deposits 0.05-60 m thick), Halley-type comets
can supply (0.2-20) x 10(16) g of water to the poles (0.07-7 m of
ice), and asteroids can provide (0.4-20) x 10(16) g of water to the
poles (0.1-8 m of ice). Although all these external sources are nominally
sufficient to explain the estimated amount of ice currently at Mercury's
poles, impacts by a few large comets and/or asteroids seem to provide
the best explanation for both the amount and cleanliness of the ice
deposits on Mercury. Despite their low population estimates in the
inner solar system, Jupiter-family comets are particularly promising
candidates for delivering water to Mercury because they have a larger
volatile content than asteroids and more favorable orbital and impact
characteristics than Halley-type comets. (C) 1999 Academic Press.
%0 Journal Article
%1 Moses1999
%A Moses, J. I.
%A Rawlins, K.
%A Zahnle, K.
%A Dones, L.
%D 1999
%J Icarus
%K ANOMALIES; ASTEROIDS; COMETS; EARTH; IMPACT; MOON OBJECTS; PLANETS; POLAR SHORT-PERIOD SOLAR-SYSTEM; STABILITY;
%N 2
%P 197--221
%T External sources of water for Mercury's putative ice deposits
%V 137
%X Radar images have revealed the possible presence of ice deposits in
Mercury's polar regions. Although thermal models indicate that watts
ice can be stable in permanently shaded regions near Mercury's poles,
the ultimate source of the water remains unclear. We use stochastic
models and other theoretical methods to investigate the role of external
sources in supplying Mercury with the requisite amount of water.
By extrapolating the current terrestrial influx of interplanetary
dust particles to that at Mercury, we find that continual micrometeoritic
bombardment of Mercury over the last 3.5 byr could have resulted
in the delivery of (3-60) x 10(16) g of water ice to tb permanently
shaded regions at Mercury's poles (equivalent to an average ice thickness
of 0.8-20 m), Erosion by micrometeoritic impact on exposed ice deposits
could reduce the above value by about a half. For comparison, the
current ice deposits on Mercury are believed to be somewhere between
similar to 2 and 20 m thick. Using a Monte Carlo model to simulate
the impact history of Mercury, we find that asteroids and comets
can also deliver an amount of water consistent with the observations.
Impacts from Jupiter-family comets over the last 3.5 billion years
can supply (0.1-200) x 10(16) g of water to Mercury's polar regions
(corresponding to ice deposits 0.05-60 m thick), Halley-type comets
can supply (0.2-20) x 10(16) g of water to the poles (0.07-7 m of
ice), and asteroids can provide (0.4-20) x 10(16) g of water to the
poles (0.1-8 m of ice). Although all these external sources are nominally
sufficient to explain the estimated amount of ice currently at Mercury's
poles, impacts by a few large comets and/or asteroids seem to provide
the best explanation for both the amount and cleanliness of the ice
deposits on Mercury. Despite their low population estimates in the
inner solar system, Jupiter-family comets are particularly promising
candidates for delivering water to Mercury because they have a larger
volatile content than asteroids and more favorable orbital and impact
characteristics than Halley-type comets. (C) 1999 Academic Press.
@article{Moses1999,
abstract = {Radar images have revealed the possible presence of ice deposits in
Mercury's polar regions. Although thermal models indicate that watts
ice can be stable in permanently shaded regions near Mercury's poles,
the ultimate source of the water remains unclear. We use stochastic
models and other theoretical methods to investigate the role of external
sources in supplying Mercury with the requisite amount of water.
By extrapolating the current terrestrial influx of interplanetary
dust particles to that at Mercury, we find that continual micrometeoritic
bombardment of Mercury over the last 3.5 byr could have resulted
in the delivery of (3-60) x 10(16) g of water ice to tb permanently
shaded regions at Mercury's poles (equivalent to an average ice thickness
of 0.8-20 m), Erosion by micrometeoritic impact on exposed ice deposits
could reduce the above value by about a half. For comparison, the
current ice deposits on Mercury are believed to be somewhere between
similar to 2 and 20 m thick. Using a Monte Carlo model to simulate
the impact history of Mercury, we find that asteroids and comets
can also deliver an amount of water consistent with the observations.
Impacts from Jupiter-family comets over the last 3.5 billion years
can supply (0.1-200) x 10(16) g of water to Mercury's polar regions
(corresponding to ice deposits 0.05-60 m thick), Halley-type comets
can supply (0.2-20) x 10(16) g of water to the poles (0.07-7 m of
ice), and asteroids can provide (0.4-20) x 10(16) g of water to the
poles (0.1-8 m of ice). Although all these external sources are nominally
sufficient to explain the estimated amount of ice currently at Mercury's
poles, impacts by a few large comets and/or asteroids seem to provide
the best explanation for both the amount and cleanliness of the ice
deposits on Mercury. Despite their low population estimates in the
inner solar system, Jupiter-family comets are particularly promising
candidates for delivering water to Mercury because they have a larger
volatile content than asteroids and more favorable orbital and impact
characteristics than Halley-type comets. (C) 1999 Academic Press.},
added-at = {2009-11-03T20:21:25.000+0100},
author = {Moses, J. I. and Rawlins, K. and Zahnle, K. and Dones, L.},
biburl = {https://www.bibsonomy.org/bibtex/2d616d5c2437f8019f1e3ebb61128e8aa/svance},
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interhash = {8e20048e5be1717a53868edc1e54bb0d},
intrahash = {d616d5c2437f8019f1e3ebb61128e8aa},
journal = {Icarus},
keywords = {ANOMALIES; ASTEROIDS; COMETS; EARTH; IMPACT; MOON OBJECTS; PLANETS; POLAR SHORT-PERIOD SOLAR-SYSTEM; STABILITY;},
number = 2,
owner = {svance},
pages = {197--221},
timestamp = {2009-11-03T20:22:07.000+0100},
title = {External sources of water for Mercury's putative ice deposits},
volume = 137,
year = 1999
}