Mikhail Korniyenko, Alexander Lynnik and Denis Yefremov fell from an Ilyushin-76 plane flying at an altitude of 10,500 meters
stratosphere
Solar-powered balloons detected strange rumblings at a height of 70,000 feet above the Earth's surface. Scientists can't identify them.
"With present threats to Greece in the E. Mediterranean an ultra-persistent airborne platform would provide critical intelligence, surveillance & reconnaissance capabilities"