(i) Project Light Brigade was the code name for the operation that the scientists were carrying out to stop the collision of the comet
with the earth. The project involved placing nuclear payload in a spaceship, sending it to intercept the approaching comet, and
detonating it by remote control. December 15 was the date when if the experiment failed, the comet would collide with the earth.
However, if it did not, then the comet would pass by at a near but safe distance.
(ii) In his letter to Duttada in October, Sir John said that the charge of the Light Brigade had begun and that they hoped for the best.
It meant that the spaceship with the payload had been launched on time.