Ann Clayborne is one of the Americans, and is on the geology team. Ann is one of the first on Mars to disagree with ideas of terraforming, a movement that soon becomes known as the Red's, with Ann as their leader. Ann believes that the planet should be studied in as much of its natural state as possible. She uses her influence in Washington to attempt to block the other colonists from terraforming, and as such, becomes disliked by many in the book. She chooses the live with her companion, Simon, and with him, the two have a child called Peter. Ann and Sax Russell are opposites in the novel. Ann also gets a rover stuck while she and the others of the first hundred are escaping the revolution, and when Frank Chalmers frees the rover, he is killed. Ann is safe in the end with the hidden colony of Hiroko.