NASA charts course to sail to the stars on largest spacecraft ever built
11 May 2000
Captain Sisko please report to the bridge
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 trillion 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.
The Marshall Center is leading NASA's transportation research for
interstellar probes. Engineers at Marshall are conducting laboratory
experiments to evaluate and characterize materials for space
sails. Materials will be exposed to harsh conditions in a simulated space
environment to test their performance and durability in extremely hot and
cold temperatures. The emphasis of the current research effort is on the
interstellar precursor missions designed to set the stage for missions to
other star systems later this century.
Marshall is partnering with NASA's Jet Propulsion Laboratory in Pasadena,
Calif. The Jet Propulsion Laboratory has overall responsibility for NASA's
interstellar missions and the Marshall Center is responsible for developing
transportation systems for the missions. Marshall's effort is part of its
Advanced Space Transportation Program, NASA's core technology program for
all space transportation. The Advanced Space Transportation Program is
pushing technologies that will dramatically increase the safety and
reliability and reduce the cost of space transportation.