Well, there's lots of explanations of the noise on here, and possible dire consequences from coming in contact with something from outer space! But is there a possibility it might be some of the junk we've left scattered all around the world, at varying altitudes? They say it's getting dangerous out there, due to all the crap we humans have thrown into orbit!
Adapt, improvise, overcome.-Gysgt Highway, Heartbreak Ridge
IN GOD WE TRUST!