Indias "Avatar": Aerobic Vehicle for Hypersonic Aerospace Transportation
When operational, it is planned to be capable of delivering a payload weighing up to 1000 kg to low earth orbit. It would be the cheapest way to deliver material to space at about US$67/kg. Each craft is expected to withstand 100 launches.
AVATAR would take off horizontally like a conventional airplane from a conventional airstrip using turbo-ramjet engines that burn air and hydrogen. Once at a cruising altitude, the vehicle would use scramjet propulsion to accelerate from Mach 4 to Mach 8. During this cruising phase, an on-board system would collect air from the atmosphere, from which liquid oxygen would be separated and stored. The liquid oxygen collected then would be used in the final flight phase when the rocket engine burns the collected liquid oxygen and the carried hydrogen to attain orbit. The vehicle would be designed to permit at least a hundred re-entries into the atmosphere.
Dr. M R Suresh, a senior ISRO official, stated that, "The dream of making a vehicle which can take off from a runway like an aircraft, and to return to the runway after deploying the spacecraft in the desired orbit (or Single-stage-to-orbit or SSTO) can be fulfilled only by the availability of more advanced high strength but low density materials so that the structural mass of the vehicle could be reduced considerably from the present levels. The advent of nano-technology could play a deciding factor in developing such exotic materials. However, the material technology available today can realize a Two Stage To Orbit (TSTO) vehicle only and the configuration of the vehicle which is being considered. However, the before realizing the RLV-TSTO it is important to perfect many critical technologies pertaining to hypersonic reentry vehicles. Hence a technology demonstrator vehicle (RLV-TD) is being developed."