Who is Martha Parker from Paris to the Moon and what is their importance?

Martha Parker, the wife of Adam Gopnik and the mother of their two children, was Adam's constant companion in this book. She was not often quoted in conversations with him or others, but she manifested as an important presence in the story. Her ideas or attitudes were often relayed in paraphrase by Gopnik, so that her personality was filtered through his perceptions. He clearly saw her as bright, temperate, and calm. On occasion she could be a little peeved if she was left at home too long while he rambled about Paris, and on one occasion she actually yelled at him for spending too much money on trivialities, but generally, she was depicted as a warm lover and a great mother to their children. She also showed flashes of humor.