As NASA’s New Horizons spacecraft barrels toward Pluto, rapidly approaching its close encounter on July 14, long-distance reconnaissance by the probe is revealing a fascinating surface geology. Far from being a bland, uniform surface, the dwarf planet seems to play host to a complex array of geological features that planetary scientists are already trying to decipher.
The New Horizons probe, hurtling ever closer to Pluto, is beginning to pick up clear signs of surface geology, including unusual polygon-shaped features and sharp transitions between bright areas and a dark region along the equator known as "the whale," project scientists said Friday.
The latest image was snapped Thursday while New Horizons was still 3.3 million miles from its target. As such, features are not yet in razor-sharp focus. But the clarity is steadily improving as New Horizons races toward Pluto at more than 31,000 mph.
The dark anti-polar cap we saw in the earlier, far-blurrier images is still a coherent if mysterious feature, a ragged patch stretching over 320 kilometres (200 miles). Its source is open to wild theorizing: a compositional change due to some To Be Determined process, a region that’s been melted and refrozen as larger crystals, a deposition spot within some temporary, nebulous atmosphere formed by stealing stray gases from Pluto, or something altogether different. Unlike the cantaloupe-texture hexagons of Pluto, Charon is home of circular features that are very likely craters. The most prominent suspected crater is a 96.5 kilometre (60 mile) diameter circle near the south pole. Bright rays radiating out from from it suggest it formed relatively recently, meaning sometime within the last billion years. The dark centre suggests the crater floor might be exposing a different type of icy material than coats most of the planet, or ice that refroze with larger, less-reflective grains after the impact. But the most interesting features of all are dark, linear areas: potential chasms. If they are chasms, we’re looking at gaping canyons that put Earth’s wimpy Grand Canyon in a corner of shame for being such a weak attempt at splitting the surface. However exactly we end up defining it, if it’s a fault or a surface disruption with depth of any type, it’s shocking us by revealing moon we thought would be near featureless and rather boring is actually home to some sort of geological activity. Or maybe Mass Effect was unintentionally truthful, and those are the flaws in otherwise perfect camouflage for a mass relay. space.io9.com
The "tail" of the dark equatorial region nicknamed the "whale" has what appears to be a large, lighter-coloured peninsula and tiny speck of light material, suggesting some kind of complex geology or broken landscape. A "polygonal feature" somewhat north of the equator could be crevasses with shapes governed by shearing minerals or some other, less obvious phenomenon.
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