| Light Sails to Orbit NASA watches from the sidelines as Cosmos 1, the first solar sail, goes up Shiny and crinkly, the material looks more like something meant to wrap frozen foods than to provide a new way to travel through space. The aluminized Mylar reflects sunlight, thereby deriving a little kick from the recoiling photons. In principle, big sheets could act as solar sails that over time would reach speeds exceeding 100 kilometers a second—far faster than chemical rockets. The first solar sail, called Cosmos 1, will go for its test flight in early 2004. The demonstration of a revolutionary way to travel to the planets and maybe even to the stars would seem to be a natural activity for NASA, which spends several million dollars every year researching advanced propulsion systems. Yet in this case, the space agency has chosen to be a bystander. Russian involvement may be one reason NASA has shied away, suggests Louis D. Friedman, executive director of the Planetary Society. Informal discussions had NASA supplying the sail material, which is tougher and, at 2.5 microns thick, half the thickness (and therefore half the weight) of the Russian film being used. "We would have gotten it for free and tested it for them," Friedman says. But NASA management never gave the go-ahead. Bureaucracy might have been a problem, he surmises, with the "upper echelons fearing private companies working with the Russians on a submarine launch." In any case, strict rules govern how closely NASA can work with other countries, remarks Hoppy Price, who was the lead solar-sail engineer for NASA at the Jet Propulsion Laboratory in Pasadena, Calif. "Possibly NASA is worried about the transfer of technology," he notes. Moreover, solar sails may provide some military advantage that the U.S. would rather not share. One proposed application, for instance, has solar sails hovering over the poles to provide valuable up-links to anyone at the Earth’s communications-starved extremities. Risk, though, is probably the main reason for NASA’s noninvolvement. Battered by a bruising report about the Columbia disaster as well as by the loss of two Mars-bound spacecraft in 1999, the agency "can’t spend taxpayer money with the level of risk" that the Cosmos 1 team is taking, notes Neil Murphy, who currently coordinates the solar-sail work at JPL. Plenty of pitfalls abound. "Concern lies with what happens to an ultrathin material over tens of meters," Friedman says, noting that engineers have no good way on the earth to test the behavior of the material in zero gravity. "You can imagine all sorts of problems—take Saran Wrap and wave it around," he offers. Ripping, fluttering and sagging would all undermine the sail’s ability to reflect photons. NASA would also want a solar-sail launch to have science-based goals to refine models and to plan the next mission, Murphy explains. Cosmos 1 is mostly a demonstration, and the components are not suitable for an extended voyage. The inflatable spars, for example, will not remain rigid for long because of the inevitable micrometeoroid impacts.
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