The fastest recorded speed for the shuttle (in orbit) is around 17,500 miles per hour. This equates to 25,700 feet per second. At normal conditions within a normal range at sea level, sound travels at 1,116 feet per second. Light travels at the speed of 186,000 miles per hour. I think that the shuttle could have been traveling 18 times the speed of sound but not 18 times the speed of light.