New Scientist
A flying carpet to take us to Pluto
A GIANT flexible solar panel that is unfurled into space like a carpet could one day make long-haul space flight possible without using nuclear propulsion. Space scientist Rudolf Meyer at the University of California, Los Angeles, has designed a "flying carpet" formed of a solar-electric membrane. The membrane would supply power to an array of ion engines, in which xenon ions are attracted to a high-voltage grid and pushed out of a nozzle.
The proposed design will require significant advances in solar panel technology before it becomes a reality. If successful, it could provide an alternative to nuclear-powered spacecraft such as NASA's planned Prometheus mission to Jupiter and its moons. Nuclear power is considered undesirable because an accident, or the dumping of crippled or spent spacecraft, would pollute interplanetary space with radioactive material.
In a paper to be published in the space-flight journal Acta Astronautica, Meyer says that the system could be lofted into orbit in the bay of a space shuttle or a similar craft (see Diagram). Once in space, the solar membrane would be fixed to its spacecraft and unfurled. The far end of the membrane would be stabilised by ion engines at its corners. Multidirectional nozzles on the engines would enable them to adjust the position of the membrane to make sure it is always facing the sun and to keep it taut. A cluster of ion engines would provide forward thrust.
Flexible solar panel technology is still in its infancy, but Meyer is confident his idea is feasible, perhaps using gallium arsenide solar cells on a flexible polyester membrane. "None of the physical principles that govern semiconductors and their coatings are being violated," he writes. At the moment such a system would be far too heavy.
The panels will need to weigh about 16 grams per square metre, rather than the hundreds of grams they now weigh.
Meyer calculates that a space probe weighing 200 kilograms with a flying carpet covering 3125 square metres could travel at 666,000 kilometres per hour, reaching Pluto in less than a year.
Propulsion researcher Geoffrey Landis at NASA's Glenn Research Center in Cleveland, Ohio, says the agency's research into thin-film solar arrays suggests that, though ambitious, the necessary technological improvements should be feasible. "If this can be achieved, the extremely high-energy ion-propulsion vehicles he proposes may be a practical alternative technology for future missions to the edge of interstellar space."
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http://www.eurekalert.org/pub_releases/2006-04/ns-afc042606.phphttp://www.newscientist.com/