Rockets and Missiles - Multistage Rockets

In some cases, rocket engineers combine solid and liquid rockets in the same vehicle in order to take advantage of the unique advantages each has to offer. A classical example is the National Aeronautics and Space Administration's (NASA's) space shuttles. The shuttles make use of 67 individual rockets in order to lift the vehicle off Earth's surface, maneuver it through space, and control its re-entry to the Earth's surface. Forty-nine of those rockets are liquid engines and the other 18, solid motors.

The three largest of these rockets are liquid oxygen/liquid hydrogen engines that provide part of the thrust needed to lift the shuttle off the pad. Two more liquid rockets, powered by a nitrogen tetroxide/monomethylhydrazine mixture, are used to place the shuttle into orbit and to carry out a number of orbital maneuvers. Another 44 nitrogen tetroxide/monomethylhydrazine rockets are used for fine tuning the shuttle's orientation in orbit.

Of the solid fuel rockets, two, the solid rocket booster motors, provide nearly 15,000 newtons (3,300,000 lb) of thrust at take-off. The remaining 16 rockets, composed of ammonium perchlorate, aluminum, and polybutadiene, are used to separate the solid rocket booster capsules from the main shuttle body for re-use.