For more than 30 years we’ve been navigating the solar system with our fists. Our spacecraft, perched atop thundering rockets the size of skyscrapers, are blasted off the face of Earth. Arriving at their destination in a headlong rush, they must pivot, then blast their retro-rockets in a desperate effort to slow down enough so that they will be lassoed by the gravity of the target planet or moon and pulled into orbit.
This brute-force approach to celestial mechanics has served us well in the past, but it is a dangerous and expensive game. For example, the freight costs to the moon, our closest neighbor, are a whopping $1 million per pound. And the retro-rockets must fire at exactly the right moment to put the spacecraft into lunar orbit. If they fail, all those millions of dollars of hardware become instant space junk, sailing right past the moon into infamy and the infinite. This fuel-hungry strategy may have been appropriate when the world’s space agencies had money to burn. But now that NASA is under intense pressure to do more with less, our future capability to explore and even exploit space may well hinge on our ability to find a gentler way through the solar system.
