Lorre being the leader, the pilot adjusted the jets to turn. "Now, would you explain this rather--er--abrupt alteration in our plans, Dr. Lorre?" "Certainly. Call the rest of the men back." Hammond did so. The mechanic appeared undisturbed; he wasn't even curious. The bio-chemist and the metallurgist were greatly interested; the doctor wondered whether the success of the polari-neutralizer had shaken the sanity of its inventor. "The universe," began Dr. Lorre, "is full of mysteries as yet unsolved. One of these is the cosmic rays. "We know little of their origin or their properties. It seems, however, that they have a marked effect on evolution. "The Kennelly-Heaviside Layer screens out most of these rays. It is as a result of this that evolution can go slowly forward toward its goal. For should all the cosmic rays reach Earth, life would devolve back into protoplasm! "In the back of the so-called Horse's Head dark nebula is a dying star. The nebula shields us from the cosmic rays it gives off. But in only a few years our sun will carry us directly in the path of a deluge of these rays against which our ionosphere will be too weak! Man will go back to the caveman days from which he emerged. But he will not stop there. He will go back to primal protoplasm. Then, because the ray barrage will be too strong for it, it will die. All life will go the same way. In less than one million years, the world will be devoid of life! "There is a way out. We can build a machine to strengthen the Heaviside Layer. It will be merely an ionoscreen around the entire world, to hold back the rays that pass the natural ionosphere. I have been given the details of the machine, and by the time we arrive on Earth I will have them down on paper--" "But how do you know all this?" the doctor interrupted. He was still in doubt about Lorre's sanity. "On Mars there is an age old civilization that faces the same peril," was the reply. "For years they have been trying to warn us of what they knew would come. Their telepathy, however, was unable to pierce our H-layer. When we emerged from it, they immediately detected our thought vibrations, which are not stopped by the ionoscreen, and began communication with the most receptive mind aboard. It happened to be mine." "So when I found you lying in a comatose condition, you were talking to the Martians?" asked Hammond, dazedly. "That's right. The sooner we can start building the ionoscreen machine as the Martians have already done, the better we'll be off. "It is likely that you are wondering as to whether I am in full possession of all my mental faculties, doctor. You will find that I am quite sane when the first Earth-Mars trip is made. The Martians are even now preparing to receive visitors from Earth. They have no space ships; their science of mechanics is not as highly developed as ours."