COSMIC BEATS

The long life of a scientific and cultural icon comes to an end

- Ian Evenden

A disjointed, globe-spanning story this month, that takes in the island of Puerto Rico, the University of Milwaukee, spinning neutron stars at the edge of the galaxy, and your PC, via James Bond and a Battlefield 4 multiplayer map.

Where to start? Well, in the late 1950s, nuclear missiles re-entering the atmosphere as part of a Soviet attack were considered to be a bit of a worry. The missiles dropped radar-reflective decoys behind them, and nobody knew enough about the upper levels of the atmosphere to tell the difference between these dummies and the real warheads coming in hot. One way to get this information, it was decided, was to build an enormous radio telescope – a huge dish 1,000ft across – reclined inside a sinkhole on Puerto Rico.

Suspended above this dish would be a 190-ton platform carrying the receivers that would read the radio waves focused by the telescope. This platform also needed to be mobile, because moving the dish itself was going to be impossible. And so it was built, officially opened in 1963, a triumph of cold war engineering. When not looking for incoming nukes or bouncing signals off the Moon to find Soviet radar installations, the dish turned out to have other uses in the field of astronomy and was soon showing results. It discovered that Mercury rotates once every 59 days instead of the previously believed 88, meaning it was not tidally locked to the Sun. It made the first radar observations of a comet, discovered the first extrasolar planets, and in 1968 provided the first evidence for the existence of neutron stars, by timing the periodicity of the Crab Pulsar.