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). 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). They 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). See also Near space NewSpace Orbital Launch Proposals Space Fellowship References External links JP Aerospace JP Aerospace Rockoons Space Frontier Foundation CATS Prize Official JP Aerospace Forum Stew Magnusson (2003), Air Force Explores Balloon-Assisted Launches, Space.com Space News, Imaginova Trade Publishing Space organizations Space program of the United States