"Suppose something should happen to Mr. Roumann or to the motor while we were half way to Mars? I mean, suppose he should die, why, we wouldn't know how to stop the motor, and we might keep on going forever."
"Oh, I guess he'll tell the professor enough about it so that in case anything happened we could start it or stop it. It's only the secret of the power that he wants to keep."
"I wonder what he wants to go to Mars for, anyhow?"
"Well, you know what he said. That he wants to get possession of some wonderful substance. I guess it is the same stuff that makes the planet seem red to us."
"What's he going to do with it?"
"I don't know."
"Wonder what it is?"
"I don't know that, either. Maybe it's some sort of a mineral, like radium."
"Radium would be valuable, if he could get that. Maybe that's what he's going after."
"No, I think not. If it was, he wouldn't be particular about not telling us. We'll just have to wait and see."