Voyager 2's "grand tour" of the outer planets was made possible by two things. The planets were aligned in space in a favourable way. This happens only once every 175 years. Also, Voyager 2 used gravity-assist to direct and accelerate it from planet to planet.
Voyager 2 uses a 3.7-m dish aerial to transmit radio signals back to Earth. A 12 m-long boom carries the magnetometers. The science boom and scan platform carry most of the other instruments, including particle and radiation detectors and two TV cameras.
The gravity-assist technique was first used with Mariner 10 in 1973 to enable the probe to visit both Venus and Mercury. On a gravity-assist mission, a probe is targeted close to a planet. The planet's gravity then makes the probe speed up and curve around the planet before being slung in another direction.
Voyager 2 is now heading out of our Solar System towards interstellar space. It set out from Earth two weeks before its sister craft Voyager 1. Voyager 1 visited only Jupiter and Saturn before heading for the stars.
It is just possible, in aeons to come, that the Voyagers might be found by intelligent beings from another planet in another solar system. In case they are, they both carry record discs called Sounds of Earth. On these discs are recorded greetings from Earth people in 60 languages, sounds from nature and the human world and, in code, a selection of photographs. Helpfully, instructions on how to play the discs are given in pictorial form on the record covers.
The path Voyager 2 took (above) through the Solar System on a 12-year,
four-planet mission of discovery that cannot be repeated for more than
a century and a half. Voyager 2 set out from planet Earth on 20 August
1977. It arrived at its last port of call, Neptune, on 25 August 1989.
Its 7-billion km journey had been so well planned that it was able to swoop
to within 5,000 km of Neptune's cloud tops. Now it is heading towards a
region called the heliopause, which marks the boundary between the Solar
System and interstellar space. In 300,000 years time it should pass within
a few light-years of Sirius, the brightest star in the sky.
Voyager 2 images
Voyager 2 sent back tens of thousands of images during its remarkable
mission. It spied the multicoloured disc of giant Jupiter (above left),
Saturn's glorious rings and several of its moons (above right). At Uranus,
Voyager 2 spotted a system of faint rings (above), seen here looking across
the rugged surface of the moon Miranda. Neptune (top left) was revealed
as a blue cloudflecked planet with dark spots, which are probably huge
storms.
Click the following buttons to view the voyager orbiting the Saturn. saturn.rm (87KB) require 
or 
saturn.avi (308KB) require .
