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Thursday, June 23, 2011

NASA’s Cassini–Huygens spacecraft has discovered evidence for a large-scale saltwater reservoir beneath the icy crust of Saturn’s moon Enceladus. The data came from the spacecraft’s direct analysis of salt-rich ice grains close to the jets ejected from the moon. The study has been published in this week’s edition of the journal Nature.

Data from Cassini’s cosmic dust analyzer show the grains expelled from fissures, known as tiger stripes, are relatively small and usually low in salt far away from the moon. Closer to the moon’s surface, Cassini found that relatively large grains rich with sodium and potassium dominate the plumes. The salt-rich particles have an “ocean-like” composition and indicate that most, if not all, of the expelled ice and water vapor comes from the evaporation of liquid salt-water. When water freezes, the salt is squeezed out, leaving pure water ice behind.

Cassini’s ultraviolet imaging spectrograph also recently obtained complementary results that support the presence of a subsurface ocean. A team of Cassini researchers led by Candice Hansen of the Planetary Science Institute in Tucson, Arizona, measured gas shooting out of distinct jets originating in the moon’s south polar region at five to eight times the speed of sound, several times faster than previously measured. These observations of distinct jets, from a 2010 flyby, are consistent with results showing a difference in composition of ice grains close to the moon’s surface and those that made it out to the E ring, the outermost ring that gets its material primarily from Enceladean jets. If the plumes emanated from ice, they should have very little salt in them.

“There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than salt water under Enceladus’s icy surface,” said Frank Postberg, a Cassini team scientist at the University of Heidelberg in Germany.

The data suggests a layer of water between the moon’s rocky core and its icy mantle, possibly as deep as about 50 miles (80 kilometers) beneath the surface. As this water washes against the rocks, it dissolves salt compounds and rises through fractures in the overlying ice to form reserves nearer the surface. If the outermost layer cracks open, the decrease in pressure from these reserves to space causes a plume to shoot out. Roughly 400 pounds (200 kilograms) of water vapor is lost every second in the plumes, with smaller amounts being lost as ice grains. The team calculates the water reserves must have large evaporating surfaces, or they would freeze easily and stop the plumes.

“We imagine that between the ice and the ice core there is an ocean of depth and this is somehow connected to the surface reservoir,” added Postberg.

The Cassini mission discovered Enceladus’ water-vapor and ice jets in 2005. In 2009, scientists working with the cosmic dust analyzer examined some sodium salts found in ice grains of Saturn’s E ring but the link to subsurface salt water was not definitive. The new paper analyzes three Enceladus flybys in 2008 and 2009 with the same instrument, focusing on the composition of freshly ejected plume grains. In 2008, Cassini discovered a high “density of volatile gases, water vapor, carbon dioxide and carbon monoxide, as well as organic materials, some 20 times denser than expected” in geysers erupting from the moon. The icy particles hit the detector target at speeds between 15,000 and 39,000 MPH (23,000 and 63,000 KPH), vaporizing instantly. Electrical fields inside the cosmic dust analyzer separated the various constituents of the impact cloud.

“Enceladus has got warmth, water and organic chemicals, some of the essential building blocks needed for life,” said Dennis Matson in 2008, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.

“This finding is a crucial new piece of evidence showing that environmental conditions favorable to the emergence of life can be sustained on icy bodies orbiting gas giant planets,” said Nicolas Altobelli, the European Space Agency’s project scientist for Cassini.

“If there is water in such an unexpected place, it leaves possibility for the rest of the universe,” said Postberg.

Sunday, November 25, 2007

Despite the hopes of many University of Wisconsin-Madison (UW) students, The Onion was not named after their student center. “People always ask questions about where the name The Onion came from,” said President Sean Mills in an interview with David Shankbone, “and when I recently asked Tim Keck, who was one of the founders, he told me the name—I’ve never heard this story about ‘see you at the un-yun’—he said it was literally that his Uncle said he should call it The Onion when he saw him and Chris Johnson eating an onion sandwich. They had literally just cut up the onion and put it on bread.” According to Editorial Manager Chet Clem, their food budget was so low when they started the paper that they were down to white bread and onions.

Long before The Daily Show and The Colbert Report, Heck and Johnson envisioned a publication that would parody the news—and news reporting—when they were students at UW in 1988. Since its inception, The Onion has become a veritable news parody empire, with a print edition, a website that drew 5,000,000 unique visitors in the month of October, personal ads, a 24 hour news network, podcasts, and a recently launched world atlas called Our Dumb World. Al Gore and General Tommy Franks casually rattle off their favorite headlines (Gore’s was when The Onion reported he and Tipper were having the best sex of their lives after his 2000 Electoral College defeat). Many of their writers have gone on to wield great influence on Jon Stewart and Stephen Colbert‘s news parody shows.

And we are sorry to break the news to all you amateur headline writers: your submissions do not even get read.

Below is David Shankbone’s interview with Chet Clem and Sean Mills about the news empire that has become The Onion.

Monday, June 23, 2008

2008 COMPUTEX Taipei, the largest trade fair since its inception in 1982, featured several seminars and forums, expansions on show spaces to TWTC Nangang, great transformations for theme pavilions, and WiMAX Taipei Expo, mainly promoted by Taipei Computer Association (TCA). Besides of ICT industry, “design” progressively became the critical factor for the future of the other industries. To promote innovative “Made In Taiwan” products, pavilions from “Best Choice of COMPUTEX”, “Taiwan Excellence Awards”, and newly-set “Design and Innovation (d & i) Award of COMPUTEX”, demonstrated the power of Taiwan’s designs in 2008 COMPUTEX Taipei.