Feb. 19 (UPI) -- Frequent deployment of satellites and re-entries by the rockets that deploy them might pose a risk to the Earth's upper atmosphere and environment, a German study published Thursday indicates. As more rockets exit and re-enter the Earth's upper atmosphere, they leave behind lithium atoms and space debris that German researchers said could cause harm. The researchers detected 10 times more lithium atoms than normal in the upper atmosphere some 20 hours after a SpaceX Falcon 9