Planetary Slingshot
Traveling to the planets is an expensive business. It takes powerful booster rockets to lift a craft into space, then give it enough "kick" to reach another world. But engineers are working on ways to propel spacecraft for a lot less money -- including an orbiting "slingshot."

The idea behind the slingshot is to use the Sun and Earth's magnetic field to fling a spacecraft from a low Earth orbit to a high orbit or beyond.

The system would use a long, skinny cable. The electrically conducting cable would spin end over end, like a stick thrown to your pet dog. It would catch a spacecraft at one end, then release it as it spins around. This would speed up the craft by a good amount.

After that, the cable would convert solar energy to electricity and feed it along the entire cable. Earth's magnetic field would push at the charged cable, boosting it back to a higher orbit for the next maneuver.

The cable could also catch a spacecraft returning to Earth after a mission to another body -- perhaps carrying samples of Mars or a comet.

The system is still in the developmental stages, but engineers have tested a similar system during shuttle missions. If the slingshot works, it could reduce the need for the upper stages that propel craft out of orbit on their way to the planets. That would cut costs by quite a bit, making it possible to fly more missions for the same amount of money.



Script by Damond Benningfield, Copyright 2004