Planetary Science

Our eternal quest to explore space continues to take us where no humans have gone before. But while we push the frontiers of the Solar System, seeking to launch spacecraft to Europa and Ganymede, we are also rediscovering our relationship with the Moon. This Focus provides a glimpse into what we know, and do not know, about planetary bodies.



Space for all pp229


The exploration of the Solar System is an expensive endeavour. The more nations engage in peaceful planetary research the better.



Back to the Moon pp234 - 236

Paul Spudis


Since the end of the Apollo era, the Moon has received relatively little attention from planetary scientists. Fresh interest from a new range of nations could lead to insights into our satellite's evolution and resources.

Did an impact blast away half of the martian crust? pp412 - 414

H. J. Melosh


The northern and southern hemispheres of Mars are topographically distinct. Crustal thickness analyses and numerical simulations suggest a giant impact just after the crust differentiated 4.4 billion years ago as a plausible cause for this dichotomy.

Mercury Redux pp564

Mortitz Heimpel & Konstantin Kabin


In January 2008, 33 years after Mariner 10 flew past the solar system's innermost planet, MESSENGER crossed Mercury's magnetosphere. Ancient volcanoes, contractional faults, and a rich soup of exospheric ions give clues to Mercury's structure and dynamical evolution.



Beyond water on Mars pp231 - 233

John Grotzinger


Mars exploration has been guided by the search for water. The more complex quest by Mars Science Laboratory for habitable environments should illuminate the Martian environmental history, and possibly deliver insights into extraterrestrial life.


News & Views

A mega-landslide on Mars pp248 - 249

Jeff Andrews-Hanna


The vast Thaumasia plateau on Mars is fringed by extensive zones of deformation. Topographic and structural analysis suggests that the plateau may have slipped in a massive landslide, deforming its margins in the process.


Books & Arts

Biology meets astronomy pp237

Ellen Stofan


Astrobiology, the study of life in the Solar System and beyond, is a relatively new field that seeks to answer a very old and fundamental question: where did we come from? Robert Jastrow (an astronomer) and Michael Rampino (an Earth scientist) have now taken a comprehensive look at astrobiology in an accessible, well-written text aimed at undergraduate students who do not pursue science as a principal subject.

Heavenly Rinds pp237 - 238

W. Bruce Banerdt


Comprising a planet's outermost portion, the crust is by far its most accessible part, and in the case of Earth it is of critical importance to sustaining life. However, the bewildering array of worlds in the Solar System means that in spite of this accessibility, a coherent understanding of crusts of the solid planets has not yet emerged. In their treatise, S. Ross Taylor and Scott McLennan have attempted to systematically survey the available evidence and current theory for crustal formation in all the observed bodies in the Solar System, and to construct a framework for understanding their diversity.



Brucite and carbonate assemblages from altered olivine-rich materials on Ceres pp258 - 261

Ralph E. Milliken and Andrew S. Rivkin


The mineralogy of the dwarf planet Ceres has long remained uncertain. The infrared spectral features of this planetary body are indicative of minerals derived from the aqueous alteration of olivine-rich materials, suggesting that Ceres is not represented by any known meteorite.

Timing of crystallization of the lunar magma ocean constrained by the oldest zircon pp133 - 136

A. Nemchin, N. Timms, R. Pidgeon, T. Geisler, S. Reddy & C. Meyer


The primitive Moon was covered with a thick layer of melt known as the lunar magma ocean, whose crystallization resulted in the Moon's surface as it is observed today. Dating of the oldest zircon so far in lunar rocks indicates that much of the magma was probably crystallized within 100 million years of the Moon's formation.


Review Article

The methane cycle on Titan pp159 - 164

J. I. Lunine & S. K. Atreya


Despite Titan's cold temperatures (about 93.7 K at the equator), fluvial and atmospheric processes are active on this moon of Saturn, with methane playing a similar role to water on Earth. However, Titan lacks a global methane ocean, and rainfall appears to be episodic.

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