Phyllis Boyle is an American geologist who is one of the first hundred on Mars. She, unlike some of the others, supports corporate control of Mars, and believes Mars is there as an extension of the Earth, as opposed to the belief that Mars should be left alone, and studied as is. As a fan of corporate control, Phyllis is placed in charge of the asteroid Clark that serves as the weighted point for the newly constructed space elevator, which makes the movement of raw materials easy to and from Mars. When the revolution occurs, however, and the space elevator is destroyed, Clark is sent spinning off. Phyllis and the rest of the crew plan to use Jupiter to spin back into the elliptical orbit of Mars, so they can escape the asteroid.