I collapsed in the chair yesterday night after a long day. My wife and daughter watched and chuckled from the couch as I nodded off. My submission to sleep was a quiet event marked only by the occasional snore, but the catastrophic rumble-tumble of rock when the roofs of lava tubes on the flanks of Mars’ second highest volcano collapsed must have shaken the ground like an earth, er, marsquake. In my personal situation, the body gave in; on Mars, the roof over former lava conduits within the volcano collapsed under their own weight after the lava drained away from beneath. This happened long ago, during the heyday of Martian volcanism, when lava welled up from multiple locations within the crust to create a whole field of volcanoes, including what would become the picturesque lava tubes of Ascraeus (as-KREE-es) Mons.
Like many of Mars’ volcanoes, this one is very similar to the Hawaiian shield volcanoes, where very fluid lavas erupt nearly continuously from one or more vents. The lava flows spread out layer after layer in large sheets across great distances, making shield volcanoes the largest both on Earth and Mars.
The Hawaiian volcanoes are produced by magmas erupting from a “hot spot” in the Earth’s crust. Given the enormous size of the Martian volcanoes and the fact that Mars doesn’t have moving crustal plates, they probably formed the very same way – stewing over hot spots in the Martian crust.
The lava tube photo is a recent release from NASA as is the latest image of the Mars Opportunity Rover parked next to Santa Maria crater on New Year’s Eve, which was taken by the Mars Reconnaissance Orbiter. Opportunity will spend about two months investigating the layering of rocks within the crater before moving on to the larger Endeavour crater four miles away. Studies by orbiting spacecraft indicate that Endeavour’s rim contains clay-bearing minerals indicating it was once wet there. The exploration of Mars has always been about ‘finding the water’ with the hopes of finding life, making the crater an ideal location for study.
On January 25, the feisty rover celebrates its 7th year on the planet – amazing for a machine that was designed to last just three months.
I can’t resist one last image, taken by space station astronaut Douglas Wheelock last November 8. To see more of Wheelock’s wonderful pix, click HERE.