>>13070987The Orbital Ascender airship would be the final flight stage from the station to orbit.[15] It would initially rise as a lighter-than-air craft from the station at 140,000 feet to 180,000 feet (ca. 42,672 m to 54,864 m). The orbiter would have to be over a mile long to gain enough buoyancy.
At 180,000 ft it would accelerate forwards using lightweight, low power ion propulsion, enabling it to rise further with additional aerodynamic lift. This would be powered by solar panels which cover most of the upper surface of the airship. The V-shaped planform and airfoil profile would allow hypersonic flight by 200,000 feet, increasing to orbital speed (above Mach 20).[13] There is a wide margin of drag-to-power ratios within which an orbital airship can attain orbit.[16]
If hit by a meteorite or space debris, this would have little effect because the inner cells are "zero pressure balloons" saying "There is no difference in pressure to create a bursting force. All a meteorite would do is to make a hole. The gas would leak out staggeringly slowly..." (Page 112).[1] They[who?] also say (page 109) that ""By losing velocity before it reaches the lower thicker atmosphere, the reentry temperatures are radically lower.... This makes reentry as safe as the climb to orbit". The skin would be made of nylon rip-stop polyethylene (page 111). On re-entry the orbital airship slows down at a very high altitude because it has such low mass with such a large cross section presented to the atmosphere (a low ballistic coefficient).
If the plan is successful, one estimate of the cost for payload to orbit is $310 per ton.
https://en.wikipedia.org/wiki/JP_Aerospace 
