The Astroliner, in theory, eliminates the two solid rocket boosters on the side of the shuttle, and replaces them with a 747 aircraft. Which will tow the Astroliner off the ground and into the air to about 20,000 feet. 60 years ago,first demonstration of the basic concept of towing an un-powered aircraft behind a powered aircraft and then releasing it for autonomous flight. It was first accomplished with the German ME321 transport glider.