We address the first several hundred million years of Earth’s history. The Moon-forming impact left Earth enveloped in a hot silicate atmosphere that cooled and condensed over ∼1,000 yrs. As it cooled the Earth degassed its volatiles into the atmosphere. It took another ∼2 Myrs for the magma ocean to freeze at the surface. The cooling rate was determined by atmospheric thermal blanketing. Tidal heating by the new Moon was a major energy source to the magma ocean. After the mantle solidified geothermal heat became climatologically insignificant, which allowed the steam atmosphere to condense, and left behind a ∼100 bar, ∼500 K CO2 atmosphere. Thereafter cooling was governed by how quickly CO2 was removed from the atmosphere. If subduction were efficient this could have taken as little as 10 million years. In this case the faint young Sun suggests that a lifeless Earth should have been cold and its oceans white with ice. But if carbonate subduction were inefficient the CO2 would have mostly stayed in the atmosphere, which would have kept the surface near ∼500 K for many tens of millions of years. Hydrous minerals are harder to subduct than carbonates and there is a good chance that the Hadean mantle was dry. Hadean heat flow was locally high enough to ensure that any ice cover would have been thin ( 4 Ga detrital zircons. If carbonates in oceanic crust subducted as quickly as they formed, Earth could have been habitable as early as 10–20 Myrs after the Moon-forming impact.

Emergence of a Habitable Planet

The pH of Enceladus’ ocean

https://www.uni-muenster.de/imperia/md/content/planetology/lectures/ss2015/143897-hottopics/castillo-rogez_and_mccord_2010.pdf

Ceres’ evolution and present state constrained by shape data

Implications from Galileo Observations on the Interior Structure and Chemistry of the Galilean Satellites

Spectroscopy of Io9s Pele plume against Jupiter by the Hubble Space Telescope in October 1999 revealed absorption due to S 2 gas, with a column density of 1.0 ± 0.2 × 10 16 per square centimeter, and probably also SO 2 gas with a column density of 7 ± 3 × 10 16 per square centimeter. This SO 2 /S 2 ratio (3 to 12) is expected from equilibration with silicate magmas near the quartz-fayalite-magnetite or wustite-magnetite buffers. Condensed S 3 and S 4 , probable coloring agents in Pele9s red plume deposits, may form by polymerization of the S 2 , which is unstable to ultraviolet photolysis. Diffuse red deposits near other Io volcanoes suggest that venting and polymerization of S 2 gas is a widespread feature of Io volcanism.

http://science.sciencemag.org/content/sci/288/5469/1208.full.pdf

Discovery of gaseous S2 in Io's Pele plume.

Infrared wavelength observations of Io by the Galileo spacecraft show that at least 12 different vents are erupting lavas that are probably hotter than the highest temperature basaltic eruptions on Earth today. In at least one case, the eruption near Pillan Patera, two independent instruments on Galileo show that the lava temperature must have exceeded 1700 kelvin and may have reached 2000 kelvin. The most likely explanation is that these lavas are ultramafic (magnesium-rich) silicates, and this idea is supported by the tentative identification of magnesium-rich orthopyroxene in lava flows associated with these high-temperature hot spots.

T. V. Johnson

Papers

High-Temperature Silicate Volcanism on Jupiter's Moon Io

Io and the Early Earth

The Early History of Enceladus: Setting the Scene for Today's Activity

Role of Hydrothermal Geochemistry in the Geophysical Evolution of Icy Bodies