"Stand at ease, Duport. As long as you're early, we might as well start the briefing now." On an impulse, he went to the projection screen and touched a switch which flashed on a photomap of the lunar landing area. He pointed to a particular object which was visible only because of the long shadow it cast. "As you are well aware, Duport, the research station is here, near the center of the Crater of Copernicus. The three trips so far by the _Quixote_ have been sufficient to set up the dome and to land enough equipment to keep the colony independent for several months if necessary. So far, there aren't any men there. That's our job, the _Prospero's_. We're going to have five passengers with us, research scientists, I haven't met them yet. All I know about them is that one is American and one Russian. Our job is to get them into the station, alive, and then bring back the ship. What they do up there afterward is none of our business." "Yes, sir," Duport answered, still at attention. "I have already been told this." "Yes, I haven't told you anything that you don't already know. And of course you also know that the bottom of Copernicus Crater, like all other flat areas on the Moon, is a kilometer deep with nearly molecular dust, micrometorite residue. You know that before the first landing by the _Quixote_, it was necessary to explode a hydrogen bomb in order to fuse the surface of the dust into a thick crust of glass, in order to get a stable landing stage." The American paused, turned away from the photomap, and looked at Duport again. "Yes sir." * * * * * "But something you don't know is that certain automatic instruments left at the station by the _Quixote_ have given an indication that this landing crust was weakened by the last lift-off. The instruments may be wrong, or they may be right. We're going to find out." "I--see." "Yes." The veteran leaned against the wall and looked at the boy's eyes. "The _Quixote_ is a heavy ship, and the _Prospero_ is heavier. We're going to have to set her down easy. _Very_ easy. That crust is hard, but thin. You know what will happen if the ship breaks through. The rocket nozzles will clog with dust, and the ship will sink to the cabin bubble. We'll be stuck on the Moon." "Yes sir," was all that Duport said. "Yes _sir_! The point is, Duport, that every member of the crew is going to have to function as part of the machine, the radioman included. The slightest error could be crucial on this one. You're going to have to leave your nerves behind. Once we set her down, we should be all right. But I hope to God your training program has really got you ready for this."