SUMMARY OF ROCKET PROPULSION
For humans, the conditions of space begins at about 45,000 feet (13,700 meters).
A satellite can orbit the Earth at an altitude of approximately 100 miles (160 kilometers).
http://www.andrews-space.com/en/employment/index_image.gif
The region beyond Earth is our most challenging final frontier.
Perhaps the biggest reason we want to explore space... is the irresistible phenomenon of the unknown.
HOWEVER;
The only device that can get us to these heights and back, are rockets and their propulsion systems.