After the Second World War, work continued on the aerodynamics of bombs, machine gun ammunition, rockets and other projectiles. It also continued on the vulnerability of aircraft to attack and the development of techniques to record projectiles in flight and duplicate various effects experimentally.
During the 1950s the King's Marsh was used as an experimental range for recording the flight paths of air-launched rockets. Fired from above the airfields the rockets were recorded by a series of cameras triggered by infrared sensitive cells, which could detect the rocket as it passed over.
In the peaceful atmosphere of today it is difficult to imagine the noise generated by these trials as the Gloster Meteor jets passed over at full speed and at a height of only 50 feet (15 metres).
In 1968 work started on the top secret Anglo-American System 441A 'over-the-horizon' (OTH) backscatter radar project, finally code-named 'Cobra Mist'. The Anglo-American project, whose main contractor was the Radio Corporation of America, was set up to carry out several 'missions', including detection and tracking of aircraft, detection of missile and satellite vehicle launchings, fulfilling intelligence requirements and providing a research and development test-bed.
A multi-million pound project, it was plagued by a severe 'noise' problem of an undetermined origin which resulted in a major reduction in detection capability. An investigation into this problem by a joint US/UK Scientific Assessment Committee (SAC) led to a report and recommendations in early 1973 from which came a joint US/UK decision to terminate operations at Orford Ness, based on economic and 'other considerations'.
An integral part of the project, beyond the building stood 18 'strings' of antennae in the shape of a large open fan, until they were removed in the mid 1970s. This fan was accompanied by a large aluminium 'ground net' covering some 80 acres of Lantern Marsh to the north of the site. 'Cobra Mist' is also well known for its alleged associations with UFOs. The large grey steel building currently houses radio transmitters that until recently broadcast the BBC World Service.