The Consolations of Physics by Tim Radford – review
The space probe Voyager 1 was launched on 5 September 1977. Its identical twin, Voyager 2, had a 16-day head start on their grand tour of the outer planets. Each had a computing system with about one-millionth of the capacity and capability of a modern smartphone. The Voyager missions were designed to take advantage of a planetary conjunction that happens once every 175 years when Jupiter, Saturn, Uranus and Neptune are on the same side of the sun. A spacecraft launched at the right time could visit all of them in turn, using the gravity of each planet as a slingshot to make it to the next.
Travelling at a million miles a day, the duo completed the grand tour in 1989. Voyager 1 became the first human-made object to leave the solar system and enter interstellar space in August 2012 and is heading towards a star called AC+79 3888. Some 17.6 light years from Earth, Voyager 1 should swing past it in about 40,000 years.
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