As global warming and greenhouse gases raise temperatures near the Earth's surface, they cool the outer atmosphere and may change the orbits of global-positioning satellites, a group of scientists said in a commentary.
Those falling temperatures in the upper atmosphere create lower air density, according to the commentary in yesterday's issue of the journal Science, and that may affect the paths of satellites circling the Earth, the commentary said. “Temperature directly affects atmospheric density,” wrote lead author Jan Lastovicka, of the Institute of Atmospheric Physics in Prague. “At altitudes between 200 and 800 kilometers, atmospheric drag causes measurable decay of the orbits of satellites and space debris.” Twenty-four satellites orbit the Earth to form the Global Positioning System, which is used for navigation, according to the Federal Aviation Administration's Web site. Changes in the ionosphere, where satellites orbit, can affect how radio waves travel, making GPS systems less effective, the commentary said. The scientists estimated that the air cools about 17 degrees Celsius (63 degrees Fahrenheit) every decade at distances of 217 miles (350 kilometers) from the surface, the commentary said. In the atmosphere closer to the Earth, the air density has decreased by 2 to 3% a decade, a figure that accelerates both after 1980 and as measurements are taken farther from the Earth, the scientists wrote. “The upper atmosphere is generally cooling and contracting,” the scientists wrote. The “dominant driver” of the trend is buildup of greenhouse gases, they said; thus, human- generated gases “influence the atmosphere at nearly all altitudes between ground and space, affecting not only life on the surface but also the space-based technological systems on which we increasingly rely.” Satellites' lifetimes are also affected by their energy sources, instrument failures and the competence of command centers, the commentary said. (Bloomberg)
Producing journalism that is worthy of the name is a costly business. For 27 years, the publishers, editors and reporters of the Budapest Business Journal have striven to bring you business news that works, information that you can trust, that is factual, accurate and presented without fear or favor.
Newspaper organizations across the globe have struggled to find a business model that allows them to continue to excel, without compromising their ability to perform. Most recently, some have experimented with the idea of involving their most important stakeholders, their readers.
We would like to offer that same opportunity to our readers. We would like to invite you to help us deliver the quality business journalism you require. Hit our Support the BBJ button and you can choose the how much and how often you send us your contributions.
