Tar sands on Iapetus.Tar sands Tar sands is a common name of what are more properly called bituminous sands, but also commonly referred to as oil sands or (in Venezuela) extra-heavy oil. They are a mixture of sand or clay, water, and extremely heavy crude oil. on Iapetus One of the solar system's most unusual-looking moons is Saturn's "two-faced" Iapetus, icy-bright on the side that faces behind as the satellite circles in its orbit, but darkened dark·en v. dark·ened, dark·en·ing, dark·ens v.tr. 1. a. To make dark or darker. b. To give a darker hue to. 2. To fill with sadness; make gloomy. 3. on the "leading" hemisphere by some unidentified material about 10 times less reflective. Now a researcher says spectral measurements of the dark side resemble those of tar sands on Earth. Tar sands, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. Edward A. Cloutis of the University of Alberta in Edmonton, consist of clays, bitumen bitumen (bĭty  `mən) a generic term referring to flammable, brown or black mixtures of tarlike hydrocarbons, derived naturally or by distillation from petroleum. (a complex array of variously polymerized hydrocarbons), quartz grains, water and lesser amounts of a few other minerals. After studying tar-sand samples from northeastern Alberta, consisting of viscous, organic material embedded in sediments, Cloutis reports in the July 14 SCIENCE that the best match for the dark-side spectrum of Iapetus is a mixture of 90 percent clay and 10 percent coal tar coal tar, product of the destructive distillation of bituminous coal. Coal tar can be distilled into many fractions to yield a number of useful organic products, including benzene, toluene, xylene, naphthalene, anthracene, and phenanthrene. representing organic material. Still, he notes that neither the specific clay-coal tar mixture nor the tar sand in general provides a perfect spectral match for Iapetus' dark stuff. An iron-substituted clay "seems to be a necessary component," he says, and other materials--such as some amount of a highly polymerized hydrocarbon--improve the spectrum. For now, Iapetus remains an enigma. |
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