The Kelly Space & Technology Astroliner Space Launch System was a two-stage-to-orbit, towed space launch concept. Towing an aerodynamic vehicle to an altitude of 6,000 m yielded higher system performance due to vacuum engine performance, reduced drag and gravity losses, and aerodynamic lift during flight. After separation from the 747 towing aircraft at 6,000 m and Mach 0.8, the Astroliner would boost itself to 2750 m/s and 110 km altitude before releasing an expendable upper stage (4.2 m diameter x 7.6 m long) and payload (4.85 meter diameter x 7.56 meter long). The upper stage was capable of delivering a 5,000 kg payload into a 185 km 28.5° orbit at a cost per launch of $ 22 million - 40% of the cost of existing launchers.
Following release of the upper stage, Astroliner would continue on its suborbital trajectory, re-enter the atmosphere, and land at a conventional runway. The contemporary Pioneer Rocketplane Pathfinder design of the same period had a similar approached, but used aerial refuelling instead of towing to reach a similar launch point. The first operational flight for the Astroliner was planned in 1999 for early 2002.
LEO Payload: 5,000 kg. to: 185 km Orbit. at: 28.0 degrees. Core Diameter: 6.2 m. Total Length: 48.0 m. Launch Price $: 22.00 million. in 1999 price dollars.