The rockets are commonly used to take readings or carry instruments from 50 to 200 km above the surface, the region above the maximum altitude for balloons and below the minimum for satellites. The term 'sounding' is taken from the maritime expression.
A common sounding rocket consists of a solid-fuel rocket motor and a payload. The flight is a simple parabolic trajectory and the average flight time is less than forty minutes. The rocket consumes its fuel on the rising part of the flight then separates and falls away, leaving the payload to complete the arc and return to the ground via a parachute.