“The Tall, Tanned, Young Earthman proudly touched the silver comet emblem on the chest of his gray space jacket. It was the rocket man's emblem, the highest rating a space pilot could achieve. Ian Walker's four young companions - a Martian, a Venusian and two Mercurians - wore the same emblems. They had just finished their final exams and were looking out the windows of the speeding rocket ship with the same impatience as Walker. Below was the forbidding, wild, cold side of Mercury, an ever-dark landscape that had never seen the sun. Crushed black mountains and frozen black plains, riddled with huge cracks, stretched out, bathed in the light of distant stars...”