Sunlit Side of the Planet Mercury (NASA, MESSENGER, 10/02/13) (Photo credit: NASA’s Marshall Space Flight Center)
Ever since the MErcury Surface, Space ENvironment, GEochemistry and Ranging satellite – MESSENGER – went into orbit around the tiny planet last year, astronomers have realised that earlier theories about the origins of the planet were faulty, as data has indeed revealed that Mercury could not, as most textbooks state, have formed simply as a hot ball of molten iron, being much more chemically and geologically diverse than our own moon, which was once thought similar.
The data has revealed that unusual radar-bright deposits, quite possibly water. are to be found hidden, in permanently shadowed areas at the planet’s poles. With a rich volcanic history, Mercury is unlike the moon, in that it possesses extensive lowlands, only a few miles in elevation, above the mean planetary surface. These are littered with so-called mass concentrations, of asteroids that once hit the planet, similar to those found on the moon in the 1960s.
The fiery planetary surface is pockmarked by so-called hollows, whose bright appearance suggests that in the distant past, unknown volatile material erupted from isolated pockets on the surface of this odd world, which has an interior consisting of various alloys.
A solid iron sulphide mantle lays beneath the thin rocky crust, atop a liquid outer shell, below which is an layer of iron silicate enclosing an iron core, this mix of elements ruling out Mercury having come into existence under extremely hot conditions.
The reality is that the planet might simply have formed under cooler conditions, an idea bolstered by emerging models showing there could be comparatively cool, dynamically dead zones near to stars, trapping materials normally driven off by intense heat..
1990s research pointed to Mercury’s polar regions holding water ice which is preserved in permanently frozen shadowed polar craters – the condition existing because, as with our own moon, the spin axis of the planet is nearly perpendicular to its orbit, so the poles never see sunlight.
Add to this the news that the Cassini spacecraft has sent back data showing that there is almost certainly liquid water on the moon of Saturn called Titan, and the news that Mars could house H2o in quantity as well, and you begin to appreciate that human exploration of the solar system, and survival on hostile worlds, is much more likely with the knowledge of water being present on so many of our planetary neighbours.
Planets of the Solar System (Photo credit: Wikipedia)
I have been writing for pleasure for half a century, but only started writing for money around 1994. Since then I have had a few thousand articles, stories and poems published on line and in print all round the world.
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