Monday, April 12, 2004

The Shadow of a Titan 04.07.04 What does your shadow say about you? When Saturn's largest moon, Titan, passed in front of the Crab Nebula last year, it created an X-ray "shadow." Images captured by NASA's Chandra X-ray Observatory during the rare event told astronomers a great deal about Titan's atmosphere -- important planning information for the Cassini-Huygens mission to Saturn. Image to left: Titan's transit enabled Chandra to image the one-arcsecond-diameter X-ray shadow cast by the moon (inset). This tiny shadow corresponds to the size of a dime as viewed from about two and a half miles. Click image for full size version. Credit: NASA/Chandra X-ray Center/Penn State University "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Pennsylvania State University's Koji Mori. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." The Crab Nebula, a supernova remnant, is bright with X-rays. So, when Titan -- the only moon in our Solar System with a thick atmosphere -- crossed its path, Chandra observed a gap, or "shadow," in the otherwise bright field of X-radiation. The shadow was one arcsecond in diameter -- about the size of a dime seen from two and a half miles away! Images showed that the diameter of Titan's X-ray shadow was larger than the diameter of the moon's solid surface. Why the difference? The answer: Titan's atmosphere. The difference in diameters reveals that the X-ray absorbing region of the moon's atmosphere reaches from the surface to a height of about 550 miles. The upper atmosphere's extent is consistent with Voyager 1's 1980 measurements, or 10-15 percent larger. But according to Hiroshi Tsunemi of Japan's Osaka University, Saturn was closer to the sun in 2003, so possibly prompting Titan's atmosphere to expand slightly from increased solar heating. Voyager 1 took measurements of Titan's atmosphere at heights below about 300 miles and above 600 miles. But until the Chandra observations, no measurements existed at heights ranging from 300 to 600 miles. Most of Chandra's images are made by focusing X-ray emissions from cosmic sources, but Titan's X-ray shadow image was produced more like a medical X-ray. That is, the X-ray source (the Crab Nebula) is used to make a shadow image (Titan and its atmosphere) that is recorded on film (Chandra's Advanced CCD Imaging Spectrometer). Image above: An illustration of Crab, Titan's shadow and Chandra. Click image for full size version. Credit: Chandra X-ray Center The Cassini-Huygens spacecraft will reach Saturn this coming July, beginning a four-year tour of the planet, its rings and its moons. Because the tour will include close flybys of Titan that will take Cassini as close as 600 miles -- as well as the launching of the Huygens probe that will land on Titan's surface -- scientists want to know as much as possible about the extent of Titan's atmosphere. "If Titan's atmosphere has really expanded, the trajectory will have to be changed," Tsunemi explained. Considering how rarely Titan passes the Crab Nebula, it's good that Chandra was in position to record the event. It turns out a simple shadow can be very informative, indeed. To view the full text of this release, visit: http://chandra.harvard.edu/press/04_releases/press_040504.html Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov 7:19:04 PM    comment []

WHILE DUPONT IS MOVING ITS R&D TO INDIA AND CHINA IT IS LAYING OFF A BOATLOAD OF PEOPLE IN THE UNITED STATES: DuPont to Eliminate 3,500 Jobs As High Gas Prices Take a Toll By THADDEUS HERRICK Staff Reporter of THE WALL STREET JOURNAL April 13, 2004 Buffeted by high natural-gas prices in the U.S., DuPont Co. said it plans to cut 3,500 jobs, or about 6% of its work force, by the end of the year. The move is part of a plan announced last year by the nation's No. 2 chemical manufacturer to cut costs by $900 million and focus on faster-growing markets, among them South America, Eastern Europe and Asia. The Wilmington, Del.-based company said employees in North America and Western Europe will bear the brunt of the cuts, which are expected to save the company about $325 million a year. DuPont said it will eliminate about 3,000 positions and cut an additional 500 through attrition. Though analysts said the number of job cuts were in line with expectations, union leaders said they had assumed no more than 2,500 positions would be eliminated. DuPont spokesman Clifton Webb said "the number is the number we determined is appropriate." The company said it expects the move to result in a charge of about 17 cents to 19 cents a share, largely for employee-severance costs, adding that it will determine the exact charge during the second quarter. Charles O. Holliday Jr., DuPont chairman and chief executive, said the moves are crucial to staying competitive. High natural-gas prices in the U.S. -- because of increased demand and a shortage of supply -- have put U.S. chemical makers at a disadvantage compared with those elsewhere. Chemical manufacturers use natural gas, and in some cases crude oil, as a raw material to make chemicals and to power their plants. "These are difficult but necessary decisions," Mr. Holliday said. DuPont's efforts to cut costs mirror those of Dow Chemical Co., the largest chemical maker in the U.S. and one of the few American chemical companies to significantly improve its results amid tough industry conditions. Dow Chemical did so last year in part by cutting 3,500 jobs, or about 7% of its work force. DuPont's cuts, which will be spread across the company's business units, are expected to affect all levels of the work force, including management. Shares of DuPont rose 63 cents, or 1.5%, to $44.06 in 4 p.m. composite trading on the New York Stock Exchange. The job cuts come in addition to the $4.2 billion sale of Invista, DuPont's textiles subsidiary, to Koch Industries Inc. in a deal scheduled to close by the end of this month. Invista has about 18,000 workers. DuPont said it expects to save about $375 million in fixed costs by reducing spending in areas such as contract services, supply procurement, telecommunications and information technology, and another $200 million by focusing on higher-value products with lower energy costs. 7:16:06 PM    comment []