Theory:

     The success of the experiment depended on how massive the comet was. Nobody could estimate; everybody hoped that it was not very massive.
 
     “Do you think we will succeed?” Duttada asked Sir John Macpherson for his opinion. During the week the two had developed considerable affinity for each other.
 
     “Mr Dutta, I will give you an honest answer! I am not buying any Christmas presents till December 15.”
 
     Duttada toured the British Isles for two weeks after the conference and he had a pleasant time visiting observatories and exchanging views with amateur as well as professional astronomers. On his return he was greeted by the inevitable vast crowd of friends, social leaders, students and the usual hangers-on. Loaded with garlands and bombarded by questions from the press he somehow made his way to the waiting car.
Explanation:
 
Despite the scientists' decision to launch a spacecraft with a massive nuclear explosion, the experiment's success largely depends on the comet's size. No one could tell how massive the comet was since no one could predict its size.
 
Scientists were working on the 'Project Light Brigade' with the support of nuclear power on Earth, hoping that it would successfully divert 'Comet Dutta' and rescue the Earth. Scientists and experts at the conference hall hoped that the 'Project Light Brigade' would succeed, but they were uncertain.
 
Duttada was sceptical about the effectiveness of the 'Project Light Brigade,' therefore he sought Sir John Macpherson's opinion. Duttada and Sir John Macpherson became good friends during the one-week conference. Sir John answered Duttada's question by saying he would wait until December 15 to buy Christmas gifts. It indicates that even Sir John suspected the success of the 'Project Light Brigade'.
 
After the conference was over, Duttada stayed in England for about two weeks, and he had a pleasant time visiting observatories. He met with amateur and professional astronomers and shared ideas with them.
 
Duttada returned to India following a three-week stay in England. When he arrived back at the airport, he was greeted by a huge gathering of close friends, social leaders, students, and the usual hangers-on. People assumed that Duttada was invited to England because he discovered Comet Dutta. He made his way to the waiting car, loaded with garlands and bombarded with questions from the press.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Massive
Very large or heavy
2.
Affinity
A close relationship between two people or things
3.
Observatory A building with a telescope or other equipment which astronomers use to observe stars, planets, weather, etc
4.
BombardTo attack a place with bombs or guns
5.
Hanger-onSomeone who tries to be friendly with a rich or important person in order to
Reference:
National Council of Educational Research and Training (2008). The Comet - II — JAYANT NARLIKAR (pp. 81-87). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.