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The study of volcanoes has captivated scientists of many disciplines for centuries, culminating in today's inherently multidisciplinary field of volcanology. It is perhaps the enticing interplay of volcanic activity (eruptions) [...]

During the Near Earth Asteroid Rendezvous (NEAR)--Shoemaker's low-altitude flyover of asteroid 433 Eros, observations by the NEAR Laser Rangefinder (NLR) have helped to characterize small-scale surface features. On scales from meters to hundreds of meters, the surface has a fractal structure with roughness dominated by blocks, structural features, and walls of small craters. This fractal structure suggests that a single process, possibly impacts, dominates surface morphology on these scales., The NEAR--Shoemaker mission (1) has measured the shape of asteroid 433 Eros from orbit with a laser altimeter (2), enabling quantitative assessments of the asteroid's surface morphology at scales of [...]

Measurements from the Near Earth Asteroid Rendezvous (NEAR)--Shoemaker Laser Rangefinder (NLR) indicate that asteroid 433 Eros is a consolidated body with a complex shape dominated by collisions. The offset between the asteroid's center of mass and center of figure indicates a small deviation from a homogeneous internal structure that is most simply explained by variations in mechanical structure. Regional-scale relief and slope distributions show evidence for control of topography by a competent substrate. Impact crater morphology is influenced by both gravity and structural control. Small-scale topography reveals ridges and grooves that may be generated by impact-related fracturing., The sizes and shapes of asteroids contain information about the thermal, collisional, and dynamical histories of these bodies, many of which are remnants of the materials from which the solar [...]

Elevations measured by the Mars Orbiter Laser Altimeter have yielded a high-accuracy global map of the topography of Mars. Dominant features include the low northern hemisphere, the Tharsis province, and the Hellas impact basin. The northern hemisphere depression is primarily a long-wavelength effect that has been shaped by an internal mechanism. The topography of Tharsis consists of two broad rises. Material excavated from Hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary. The present topography has three major drainage centers, with the northern lowlands being the largest. The two polar cap volumes yield an upper limit of the present surface water inventory of 3.2 to 4.7 million cubic kilometers., Long-wavelength topography (changes in topography over scales of hundreds to thousands of kilometers) reflects processes that have shaped Mars on a global scale and thus is of particular interest in [...]

Volcanoes and the dynamic processes by which they are formed are inherently intriguing topics in Earth and planetary science, in part because of the many remaining mysteries associated with them. [...]

Volcanoes and the dynamic processes by which they are formed are inherently intriguing topics in Earth and planetary science, in part because of the many remaining mysteries associated with them. [...]

Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5-kiLometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied. Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily [H.sub.2]O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x [10.sup.6] to 1.7 x [10.sup.6] cubic kilometers is about half that of the Greenland ice cap. CLouds observed over the polar cap are likely composed of [CO.sub.2] that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography., The north polar ice cap of Mars is one of the largest present-day reservoirs of volatiles on that planet and preserves the record of seasonal cycles of carbon dioxide and [...]