In my last posting on the MESSENGER mission, I said that the probe would be photographing parts of Mercury we hadn’t seen before. Here is one of the first pictures from such areas from a January 15, 2008 press release:
Why hadn’t we been able to take pictures of this side of Mercury before? The research team explains in their press release:
When Mariner 10 flew past Mercury three times in 1974 and 1975, the same hemisphere was in sunlight during each encounter. As a consequence, Mariner 10 was able to image less than half the planet. Planetary scientists have wondered for more than 30 years about what spacecraft images might reveal about the hemisphere of Mercury that Mariner 10 never viewed.
So, how does this hemisphere compare to what we’ve seen before? Again, the research team:
Like the previously mapped portion of Mercury, this hemisphere appears heavily cratered. It also reveals some unique and distinctive features. On the upper right is the giant Caloris basin, including its western portions never before seen by spacecraft. Formed by the impact of a large asteroid or comet, Caloris is one of the largest, and perhaps one of the youngest, basins in the Solar System. The new image shows the complete basin interior and reveals that it is brighter than the surrounding regions and may therefore have a different composition. Darker smooth plains completely surround Caloris, and many unusual dark-rimmed craters are observed inside the basin. Several other multi-ringed basins are seen in this image for the first time. Prominent fault scarps (large ridges) lace the newly viewed region.
As more pictures from this first Mercury flyby become available, they should become available at: http://messenger.jhuapl.edu/gallery/sciencePhotos/search.php?form_keywords=3. Each photo comes with an extensive description.
Filed under: astronomy, space exploration | Tagged: Mercury, Messenger
