dropped, the aircraft returns and everything is now ready for D-Day. Nothing has been left to chance by the scientists, and, of course, every one of you has, by this time, done your own particular job to ensure that it will not be because of you that something goes wrong.
      Now comes the trying time for everyone, particularly the Task Force Commander and the Scientific Director, for they have to ensure that the nuclear weapon is dropped when weather conditions are just right. A heavy load rests upon the scientists of the Theoretical Predictions Group for they, in close collaboration with the Meteorological Staff, have to study weather reports and from these predict the fallout pattern. When the Predictions Group decide that forecast conditions are favourable, the Task Force Commander and the Scientific Director give the order to begin the Pre-firing Phase which means that the weapon will be dropped 24 hours from then. All personnel now have to carry out the final checks and adjustments just as in the Operational Rehearsal. The Decontamination Group, with the R.A.F., make final preparations to the cloud sampling aircraft and the Health Physics Team ensure that all is ready for subsequent contamination checks, including the provision of protective clothing for personnel detailed to enter any radioactive areas.
      In the last few hours before the Pre-firing Phase ends the final weather reports are scrutinized. Should the weather still be favourable, the Task Force Commander and the Scientific Director agree to order the commencement of the Firing Phase. The aircraft takes off, the target area having been evacuated, and the captain of the aircraft is the man with the "load". On his journey he keeps in radio touch with the Joint Operations Centre on Christmas Island and also with H.M.S. Narvik, the Technical Control Ship. Even at this stage should the weather suddenly deteriorate or any of the vital equipment develop a fault, the flight could be called off. All being well, the final run is made; the bomb is dropped; and all that has been planned and worked for happens: the explosion of a megaton yield nuclear bomb.
      The explosion sets off a train of events, for it is not the end but rather the beginning of intense activity. Measuring and recording equipment which operated at the time of the explosion has to be examined and calculations made to evaluate results. The scientists of the Health Physics Team, responsible for ensuring safety of personnel, go into action, clothing with special outfits the people who have to go into the contaminated area, and making arrangements to check areas for radioactivity before anyone enters. The Royal Air Force also is busy at Christmas Island for it has to send aircraft off to sample the cloud.
      Finally, all the aircraft return to base, all the information is gathered and the results checked, and everyone retires for a period of well-earned relaxation.