Rockoon

A rockoon (from rocket and balloon) is a solid fuel sounding rocket that, rather than being immediately lit while on the ground, is first carried into the upper atmosphere by a gas-filled balloon, then separated from the balloon and automatically ignited. This allows the rocket to achieve a higher altitude, as the rocket does not have to move under power through the lower and thicker layers of the atmosphere.

The original concept was developed by Cmdr. Lee Lewis, Cmdr. G. Halvorson, S. F. Singer, and James A. Van Allen during the Aerobee rocket firing cruise of the U.S.S. Norton Sound on March 1, 1949.

A serious disadvantage is that balloons cannot be steered and consequently neither the direction the launched rocket moves in nor the region where it will fall is easily adjustable. Therefore, a large area for the fall of the rocket is required for safety reasons.