“I’d like nothing better than to have you two stay on,” the captain said. “But you must consider Mr. Mulroy and all the police forces who are working to uncover the mystery of your disappearance. Right, fellows?” “Yes, Sir,” they both agreed reluctantly. “We must make full use of the time left you to finish seeing the marvels of the _Carefree_. I said I’d show you the observatory today. What do you say we go there now? I’ve got some double-star photos I want to check on.” The boys liked the idea and went with their host along the zero-gravity tunnel toward the observatory. The observatory was a “bubble” attached to the _Carefree_’s center tube or axle, just a short distance from the air lock through which Garry and Patch had first entered the ship. The observatory was such that it never rotated with the tube or the rest of the ship. In this way its telescopes could always keep focus on objects in space. Three pairs of magnetic shoes clicked along the metal floor of the observatory as Captain Eaton led the boys to the reflector telescope, whose big six-inch eye was pointed out into space. Captain Eaton looked over a camera which was attached to the eyepiece of the telescope. Then he unfastened the camera and took it off. “The picture has been exposed long enough,” the skipper said. “It takes a pretty long time for a photograph to be made in the heavens, you know. But when you give it full exposure, it shows you much more than your naked eye can do.” Garry studied a satellite chart on the wall. “I didn’t know there were so many satellites whirling around the earth. So many different kinds and sizes too!” he said. “Yes, there are many more than one would imagine,” the captain agreed. “Here, let me show you some of them on the chart. The pictures you see are exactly the way each satellite looks, and they are all drawn in proportion.” Garry and Patch studied the chart with its multitude of different shapes and sizes. There were satellites that resembled drums and others like round balls. Some were torpedo shaped, and some were circular and flat like “flying saucers.” There were giant satellites, wherein people lived and worked, and many of them were in the shape of huge revolving wheels. Some of them had no regularity at all, appearing to Garry to resemble more than anything else huge space insects, bristling with antennas and sun mirrors. “As you probably know, fellows,” Captain Eaton said, “the Von Braun Space Station is our largest satellite of all. But there are a few others that approach it in size. For example, here is Quartermaster 10, the biggest of the depot satellites that furnish supplies to men who live in the world of the artificial moons. Here is a big fueling satellite, and over here is another big one—Spaceharbor—which is really a network of smaller moons joined together. This is a shipyard satellite where space ships are built and repaired. The _Carefree_ was built in Spaceharbor.”