satellite in orbit takes sudden right angle turn and disappears.

I was sleeping under the stars in July, or early August after a long night of amateur astronomy.  My eyes opened about 4:00 AM, judging from the constellations overhead.  I looked directly above me, and was caught off guard by a very slow moving satellite in orbit exactly overhead.  It was pretty faint.  I was barely able to detect its movement except that I watched it for over a minute, and I could see that it had slowly moved against the backdrop of stars, making its way southward.  Then, without warning, the satellite took a sharp 90 degree turn and accelerated to an incredible amount of speed in a westward direction.  Within a fraction of a second it was gone.  From what I remember I only saw it for a few moon lengths after it had taken the right turn before it was gone from view.  I was in my early teens at the time.  I refused to believe I had seen something extra terrestrial since I was a big science buff, and had always observed the scientific consen! sus refute UFO's as having been extra terrestrial spacecraft.  For over 20 years I didn't even think about what I saw until I began hearing the myriad of other UFO recounts that described lights taking sudden right degree turns like the one I saw.  It's still hard for me to accept that what I saw was extra terrestrial, but whatever I saw it seemed to violate the laws of physics, at least in terms of propulsion.
Witness indicates that the date of the sighting is approximate.  PD