By Marty Russell
I, like many folks, was saddened to see the last space shuttle launch last Friday morning with nothing waiting in the wings to replace it as America’s next manned spacecraft. NASA’s administrator was asked by a reporter following the launch what he would do the next day when he went into work now that we’re no longer flying the shuttle.
Fact is, NASA is much more than the shuttle program and one of its projects comes to fruition this weekend when the unmanned spacecraft Dawn goes into orbit around a large asteroid named Vesta which lies in the asteroid belt between Mars and Jupiter. Now sending a spacecraft to rendezvous with an asteroid isn’t anything new. But how it got there is and could be the key to continued manned spaceflight beyond Earth orbit.
That’s because Dawn, which will orbit Vesta for a year beginning Saturday before taking off to orbit another asteroid, Ceres, doesn’t use rockets which up until now was the only way to get around in space. It uses something called ion propulsion which is a first step toward constructing engines that could enable a spaceship to travel just about anywhere in the solar system without carrying along bulky fuel.
The ion thruster uses solar panels to ionize xenon and accelerate it through an electric field producing a beam of plasma that drives the ship. Whereas it would take about 600 pounds of rocket fuel to achieve an orbit around Mars, NASA says the ion propulsion system can do it with only 60 pounds of xenon.
And whereas conventional rockets exhaust all of their fuel and burn up after only a few minutes, Dawn carries enough xenon fuel to drive the propulsion unit constantly for 5.5 years albeit rather slowly at first. That’s because the propulsion system works exponentially, starting out slowly and building speed under constant acceleration.
“It would take four days to go from zero to 60,” says Marc Rayman, the project’s chief engineer at NASA. “But it ultimately achieves fantastically high velocity while consuming very little propellant. It uses only a kilogram of xenon every four days.”
The new ion drive opens up the possibility of manned spacecraft, constructed in orbit, that could travel anywhere in the solar system at a fraction of the cost of launching them from Earth while using far less fuel and providing more maneuverability and much more safety.
So while not as spectacular as a shuttle launch, I’ll be watching Saturday as Dawn approaches Vesta. It could be the dawn – no pun intended – of a new era of spaceflight and a first step toward that system “Star Trek” teased us with, warp drive, and the ability to finally travel to the stars.
Marty Russell writes a Wednesday column for the Daily Journal. He can be reached at 222 Farley Hall, University MS 38677 or by e-mail at firstname.lastname@example.org.