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LYS ey Ay E\N? CIVILIAN AND MILITARY ENVIRONMENTAL SATELLITES TO BE LINKED EARTH'S CHANGING GRAVITY FIELD Oo Gizsllite data since 1998 indi cates that the bulge in the Earth's gravity field at the equator is growing, and scientists now think that the ocean may hold the answer to the mystery of how the changes in the trend of Earth's gravity are occurring. Before 1998, Earth's equatorial bulge in the gravity field was get- ting smaller because of the post- glacial rebound, or PGR, that occurred as a result of the melting of the ice sheets after the last Ice Age. When the ice sheets melted, land that was underneath the ice started rising. As the ground rebounded in this fashion, the gravity field changed. "The Earth behaved much like putting your finger into a sponge ball and watch- ing it slowly bounce back," said Christopher Cox, a research scientist sup- porting the Space Geodesy Branch at NASA's Goddard Space Flight Center, Greenbelt, Maryland, USA. Currently, the Earth has a significant upward bulge at the equator and a down- ward bulge at the poles. "Observations of the Earth's gravity field show that some phenomena are counteract- ing the gravitational effects of PGR. Whereas PGR has been decreasing the bulge in the Earth's gravity field at the equator, this recent phenomenon is causing the bulge to increase," Cox said. "The three areas that can trigger large changes in the Earth's gravitational field are oceans, polar and glacial ice, and atmosphere," he added. Cox and colleague Dr Benjamin Chao have ruled out the atmosphere as the cause, and estimates of current glacier and polar ice melting are too small to explain the recent changes in the gravity field. "The recent reports of large icebergs calving in Antarctica can't explain this, because they were already floating in the ocean,” Cox said. Further, radar altimeter observations of the average sea level rise provided by the TOPEX/Poseidon satellite show no corre- sponding change in the rate of the global sea level increase. Consequently, mass must have been redistributed within the oceans. That's where the ocean circulation theory comes in. US$4.5 billion contract has ~ been awarded to TRW Inc. to build and deploy America's future environmental satellite system, using both military and civilian satellites. The contract is for the acquisi- tion and operations phases of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The NPOESS will combine US military and civilian environmental satellite programs into a single national system that is designed to improve weather forecasting and climate prediction. The National Oceanic and Atmospheric Administration (NOAA) has overall responsibility for the converged system as well as for satellite operations and interactions with the civil and international user communities. The Department of Defense has the lead responsibility for major systems acquisitions, including launch support. And NASA has primary responsibility for facilitating the development and incorporation of new, cost-effective technologies into the converged system. NOAA Administrator Dr Conrad Lautenbacher said: "By working together on this advanced satellite system, the three agencies will make the nation's environ- mental satellite system more efficient, cost-effective and more responsive to our country's environmental information needs. This new system will provide vital information about our weather, environ- ment, climate and oceans. In addition, our integrated effort is expected to result in taxpayers saving approximately $1.6 bil- lion over the NPOESS lifetime." TRW will develop, fabricate and deliver the NPOESS satellite and ground systems as well as provide launch support, opera- tions and support services for the system. (Source: Environment News Service, August 28, 2002, http://ens-news.com; more details at http://www. ipo.noaa.gov/) 7. aa et OBE 1g ALL dg TALK A WORLD WAR DOESNT PUT A Den. in MY