Monday, July 30, 2007

India's Space Ambitions Soar

Continued from page 1

By Mark Williams

Setting aside the more science-fictional objectives described by President Kalam--whose term just ended, on July 25--in the near future, the most technologically innovative of ISRO's projects is its scramjet RLV, named Avatar. Lowering launch costs via an RLV has, of course, been theunattainable holy grail for both the United States and Russian space programs. Avatar would weigh only 25 metric tons, with 60 percent of that the liquid hydrogen needed to fuel the turbo-ramjet engines that would power its initial aircraft-style takeoff from an airstrip and its ascent to a cruising altitude. Thereafter, Avatar's scramjet propulsion system would cut in to accelerate it from Mach 4 to Mach 8, while an onboard system would collect air from which liquid oxygen would be separated. That liquid oxygen would then be used in Avatar's final flight phase, as its rocket engine burned the collected liquid oxygen and the remaining hydrogen to enter a 100-kilometer-high orbit. ISRO claims that Avatar's design would enable it to achieve at least a hundred reentries into the atmosphere. Theoretically, given ISRO's plans for it to carry a payload weighing up to one metric ton, Avatar could thus deliver a 500-to-1,000-kilogram payload into orbit for about $67 per kilogram.

Current launch prices range from about $4,300 per kilogram via a Russian Proton launch to about $40,000 per kilogram via a Pegasus launch. Conceivably, Avatar could give India a radical advantage in the global launch market. Gregory Benford, an astrophysicist at the University of California, Irvine, and an advisor to NASA and the White House Council on Space Policy, is enthusiastic: "The Avatar RLV project will enable the Indian program to leap ahead of the Chinese nostalgia trip. Once low cost to orbit comes alive, it will drive cheaper methods of doing all our unmanned activities in space."

Still, Avatar's potentially radical advantage comes with significant restraints, given both the restricted scale of its payloads and that very low 100-kilometer orbit. That latter factor, indeed, is something of a puzzle since any satellite released at such a height will find its orbit degrading quickly. Do the Indians intend to use Avatar as a first-stage launcher, in effect, from which they will fire their satellites further up into secure orbits? Perhaps. But in that case, it's hard not to notice that Avatar, in fact, makes more sense as a missile-launch platform. After all, the United States is also working on the scramjet concept but in the context of an unmanned global cruise missile: the X-51 Scramjet-Waverider.

Could Avatar be just another military application upon which India's space scientists are piggybacking their hopes to develop a radical RLV prototype? The Indians do seem to be serious enough about Avatar as a commercial concept that they've taken out patents internationally on the design. ISRO has, relatively, a very low budget, and for Avatar to happen, Indians need to bring in international partners and funding. But if it turns out that Avatar is really just another military application that India's space scientists have used to secure funding from their military for their high aspirations, they will hardly be the first ones in the history of spaceflight to do so.