The sound of rings.Arriving at Saturn on June 30, the Cassini spacecraft sped through a 24,730-kilometer gap in the giant planet's rings. Three hours later, it crossed back in the other direction (SN: 7/10/04, p. 22). These pinpoint crossings helped shape the craft's orbit about Saturn. The ring gap that Cassini traversed isn't entirely empty. It contains bits of dust, which Cassini plowed into at a speed of roughly 20 km per second. The smoke-size dust particles did no harm to the craft, which encountered about 100,000 hits in less than 5 minutes during each of the ring crossings, Cassini investigator Donald A. Gurnett of the University of Iowa Not to be confused with Iowa State University. The first faculty offered instruction at the University in March 1855 to students in the Old Mechanics Building, situated where Seashore Hall is now. In September 1855, the student body numbered 124, of which, 41 were women. in Iowa City Iowa City, city (1990 pop. 59,738), seat of Johnson co., E Iowa, on both sides of the Iowa River; founded 1839 as the capital of Iowa Territory, inc. 1853. Among its manufactures are foam rubber, animal feed, paper, and food products. The city is the seat of the Univ. announced July 9. He and his colleagues could determine this number because whenever a dust particle strikes Cassini, the impact produces a puff (algorithm) puff - To decompress data that has been crunched by Huffman coding. At least one widely distributed Huffman decoder program was actually *named* "PUFF", but these days it is usually packaged with the encoder. Opposite: huff. of ionized i·on·ize tr. & intr.v. i·on·ized, i·on·iz·ing, i·on·iz·es To convert or be converted totally or partially into ions. i gas. An instrument counted as many as 680 of these puffs in a single second during the crossings. Gurnett's team converted these hits into audible sounds, which "resemble hail hitting a fin roof," he says. The sounds are posted online (http://science.nasa.gov/headlines/y2004 /images/hailstorm/61980main_PIA pi·a n. The pia mater. pi  al adj. 06410-Sounds-movie.mov).--R.C.
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