The Book That Saved the Earth can be considered as satire because it uses humour and exaggeration to criticise and mock the Martians' intelligence.
The Martians misinterpret Earth's books, especially the nursery rhymes. This creates a satirical commentary on cultural misunderstandings and the dangers of jumping to conclusions.
In the end, it was a simple book of nursery rhymes that became the key to saving the Earth from the invasion by an alien military force, creating an ironic and satirical twist to the story.
Think-Tank's intelligence is described in exaggerated terms as the 'most powerful and intelligent creature in the whole universe'. He is even described as having a large 'balloon brain'. This is an example of satire and mockery as Think-Tank is shown to be more pompous than intelligent.