Voyager houses a ten sided polygonal electrical bus attached to a tank of Hydrazine propulsion fuel and on this small amount of fuel has toured Jupiter, Saturn, and now both Voyager 1 & 2 are moving on to interstellar space. They have been using the flyby’s of the planets to gain speed and slingshot them on. Originally they were expected to last five years, but scientists re-planned the expected trip to take advantage of the gravity assists and see more planets.
The scientists are using a simple 20 watt transmitter on Voyager and here on Earth, a full 11 billion miles away are able to obtain the signal from a collection of extremely sensitive receivers here on Earth referred to as the Deep Space Network.
Besides going where no man has ever gone before, they have a gift with them. A golden record. On this record is greetings in the many languages of Earth as well as music and images from around the Earth. This record was put together by Carl Sagan. The hope is that even after we turn Voyager off (around the year 2020) that the record will be picked up by ET.