“Whew!” Mr. Shannon sighed. “I’m afraid I’ve had enough excitement to last me a lifetime!” “Not me, Dad,” Steve said, as the fire of adventure began to glow again in his eyes. “I won’t be satisfied until I’ve seen what lies beyond the Wheel in the Sky!” _DANGER ON THE ICE CANAL_ Steve and Sue Shannon were at Mars Port No. 13. This was one of the many colonies on the planet Mars where Earth scientists were carrying on work. It was a town of plastic tops, called domes, that were clear as glass. The town was at the center of three canals that led outward into the red desert. The Shannon twins were now touring the largest dome with Biff Warren, who worked for their father’s space cargo company. Suddenly their tour brought them to a large cafeteria where many of the workers were eating. “Umm!” Sue exclaimed. “Smell that turkey!” “Yeah!” Steve said. “It sure makes your mouth water, doesn’t it?” “Which reminds me,” Biff said, looking at his watch. “We’ll have to finish up our sightseeing pretty soon. The quicker we get back to your father’s ship, the quicker we can have our own turkey feast!” “I can hardly wait for that!” Sue sighed, as the wonderful smell of the holiday meal kept tickling her nose. When Thanksgiving dinner was finished aboard the big space freighter that had brought the children to Mars, the ship would take off into space. But before that, Biff, Sue and Steve would have to go twenty miles back down the ice canal to reach the ship. Biff had become a close friend of the young Shannons, having made trips with them to other ports in space. Sue liked Biff because of his quick smile and gentle patience. Steve liked him because he was all that Steve would like to be some day himself—a fearless, bold spaceman. They finished up their tour of the dome. They saw the room where giant machines made oxygen out of chemicals and blew it through the building so that there was fresh air to breathe all the time. And they saw the astronomy hall far up on top of the dome where scientists could see the heavens through the thin atmosphere much clearer than they could from Earth. “Isn’t it about time for the fuel rocket to be shot off, Biff?” Steve asked. Biff nodded. “I think it’s just about time,” he said. “We’ll suit up and go outside to see.” In the dressing room they put on their space suits. As though they were his own children, Biff carefully checked the young Shannons’ air tanks, built-in heaters, and their helmet radios for talking to one another. Finally Biff rubbed gelatin on their helmets so that they would not frost over in the cold that was a hundred degrees below zero. Outside they found space-suited figures gathered around the fuel rocket cannon. The cannon was pointed toward a shiny ball high up in the purple-black sky. “Look, Sis, there’s the space ship toward which they’re going to shoot the fuel rocket,” Steve said. “I see it!” Sue cried, her eyes dancing excitedly.