Lava tubes and channels of the Earth, Venus, Moon and Mars

The Magellan spacecraft was placed into an elliptical orbit about Venus in August 1990: a month later it began regular acquisition of altimetry and synthetic aperture radar (SAR) data. Ahhough Earth based radar has revealed that volcanic activity has occurred on Venus at some time in the past, no fine details, which would now become available, have previously been seen. Lava channels, collapse craters and especially lava tubes in particular should be able to be seen on the high resolution (120 m) Magellan radar images and can thus be compared with similar structures on the Earth, Moon and Mars and comparisons made. The study has shown that lava channels certainly exist on Venus but are far larger in dimensions than any known elsewhere in the Solar System. Venusian channels cannot be properly compared to those on the Earth because of their vastly larger scale but making them closer to lunar dimensions. Many collapse features on Venus may be attributed to collapses resulting from the withdrawal of magma below the Venusian surface. Although conditions on Venus such as topography, lava type temperature etc. are very favourable for the formation of lava tubes, evidence for their existence is mostly circumstantial, although very compelling.