NASA sails to the stars

NASA is setting sail for the stars - literally. NASA's Marshall Space Flight Center in Huntsville, Ala., is developing space sails technology to power a mission beyond our solar system."This will be humankind's first planned venture outside our solar system," said Les Johnson, manager of Interstellar Propulsion Research at the Marshall Center. "This is a stretch goal that is among the most audacious things we've ever undertaken. The interstellar probe will travel over 23 billion miles - 250 astronomical units - beyond the edge of the solar system. The distance from Earth to the Sun, 93 million miles, is one astronomical unit. For perspective, if the distance from Earth to the Sun equaled one foot, Earth would be a mere 6 inches from Mars, 38 feet from Pluto, 250 feet from the boundaries of the solar system, and a colossal 51 miles from the nearest star system, Alpha Centauri.This first step beyond our solar system en route to the stars has an estimated trip time of 15 years.Proposed for launch in a 2010 time frame, an interstellar probe - or precursor mission, as it's often called - will be powered by the fastest spacecraft ever flown. Zooming toward the stars at 58 miles per second, it will cover the distance from New York to Los Angeles in less than a minute. It's more than 10 times faster than the Space Shuttle's on-orbit speed of 5 miles per second.Traveling five times faster than Voyager - a spacecraft launched in 1977 to explore our solar system's outer limits - an interstellar probe launched in 2010 would pass Voyager in 2018, going as far in eight years as Voyager will have journeyed in 41 years.Johnson says transportation is quite possibly the toughest challenge with interstellar missions because they have to go so far, so fast. "The difficulty is that rockets need so much fuel that they can't push their own weight into interstellar space. The best option appears to be space sails, which require no fuel," he said.Thin, reflective sails could be propelled through space by sunlight, microwave beams or laser beams - just as the wind pushes sailboats on Earth. Rays of light from the Sun would provide tremendous momentum to the gigantic structure. The sail will be the largest spacecraft ever built, spanning 440 yards - twice the diameter of the Louisiana Superdome."Nothing this big has ever been deployed in space. We think we know how to do it, but we're in the beginning phases of turning a concept into a real design," Johnson;said.Researchers are optimistic about recent breakthroughs with strong,lightweight composite materials. A leading candidate for sails is a carbon fiber material whose density is less than one-tenth ounce per square yard - the equivalent of flattening one raisin to the point that it covers a square yard. In space the material would unfurl like a fan when it's deployed from an expendable rocket.