MESSENGER probe reveals Mercurian vulcanism
From Saswato R. Das, Scientific American, August 4th 2010, "Mercury Rising" (http://www.scientificamerican.com/article.cfm?id=mercury-messenger-flyby) comes the report that the MESSENGER probe has discovered evidence of extensive vulcanism on Mercury as recently as 1-2 billion years ago (Mercury, like the rest of the Solar System, is about 4.5 billion years old).
MESSENGER photographed a 290-kilometer-diameter double-ring impact crater, now named the Rachmaninoff Basin, that seems to have flat and very smooth plains that look like hardened lava flows. The small number of craters in Rachmaninoff imply that the plains have not existed for very long, Solomon said, guessing that they were anywhere between one billion and two billion years old. (Although that is still relatively old by terrestrial standards, it tells planetary scientists that volcanic activity continued well after Mercury formed about 4.5 billion years ago.) Researchers also found other examples of volcanic activity in the spacecraft's images. They showed two craters side by side, with one filled in, which must be from volcanic activity, according to Solomon. "Mercury has gone from being a planet where volcanism was questioned to one whose surface is dominantly shaped by volcanism," he said.
This is important, because it suggests an active geosphere; furthermore, if large active volcanoes existed on Mercury just 1-2 billion years ago, it is improbable that Mercury has entirely cooled to anything near the temperature of the ambient space, deep within. An active geosphere means segregation of minerals, which means a strong likelihood of rich metal and crystal deposits at various points on the planet. This is extremely good news for plans to colonize the Inner System. With an average density of 5.4 gm/cm (to Earth's 5.5 gm/cm) and a large core, Mercury always looked destined for mining operations, and the evidence from MESSENGER strengthens the case for a future in which Mercury has two major exports -- energy and metals.
See my earlier article, "Worlds for Man, Part 1 - Mercury" (http://jordan179.livejournal.com/26935.html) for my detailed opinion on the challenges and opportunities of Mercurian colonization.
MESSENGER photographed a 290-kilometer-diameter double-ring impact crater, now named the Rachmaninoff Basin, that seems to have flat and very smooth plains that look like hardened lava flows. The small number of craters in Rachmaninoff imply that the plains have not existed for very long, Solomon said, guessing that they were anywhere between one billion and two billion years old. (Although that is still relatively old by terrestrial standards, it tells planetary scientists that volcanic activity continued well after Mercury formed about 4.5 billion years ago.) Researchers also found other examples of volcanic activity in the spacecraft's images. They showed two craters side by side, with one filled in, which must be from volcanic activity, according to Solomon. "Mercury has gone from being a planet where volcanism was questioned to one whose surface is dominantly shaped by volcanism," he said.
This is important, because it suggests an active geosphere; furthermore, if large active volcanoes existed on Mercury just 1-2 billion years ago, it is improbable that Mercury has entirely cooled to anything near the temperature of the ambient space, deep within. An active geosphere means segregation of minerals, which means a strong likelihood of rich metal and crystal deposits at various points on the planet. This is extremely good news for plans to colonize the Inner System. With an average density of 5.4 gm/cm (to Earth's 5.5 gm/cm) and a large core, Mercury always looked destined for mining operations, and the evidence from MESSENGER strengthens the case for a future in which Mercury has two major exports -- energy and metals.
See my earlier article, "Worlds for Man, Part 1 - Mercury" (http://jordan179.livejournal.com/26935.html) for my detailed opinion on the challenges and opportunities of Mercurian colonization.