McClatchy Newspapers: From 500 miles in space, satellites track brown clouds of toxic pollutants from Asia as the machines stream across the Pacific and take aim at the western United States. A fleet of tiny, specially equipped, unmanned aerial vehicles, launched from an island 700 or so miles downwind of Beijing, are flying through the projected paths of the pollution. The satellites are taking chemical samples and recording temperatures, humidity levels and sunlight intensity in the clouds of …