Why are rockets needed?
well it depends on what you mean by "needed". The Rocket, as a tool for both rudimentary aerial and space travel and exploration was developed early in the Ming dynasty by the Chinese, and perfected almost 2000 years later by an American named Dr. Robert Goddard. The rocket has found its most profound use in space travel, and is used primarily because of its ability to provide thrust without atmospheric oxygen. This is what makes rockets differ most profoundly from jet engines, in that the oxygen needed to create and sustain combustion is found in the fuel of the rocket (either solid or liquid, but most often the latter). Hope this helps, if there are any other questions just ask!