 Why did Peter choose to go on the mission by himself rather than taking Lorelei with him?
I do not think it was what Peter called an emotion; and yet it had nothing to do with logic, either. I did not even wish that Peter were not dead, for reason had told me that he had to die. His dream was perfect; the Citadel was complete, every minutest detail provided for—on paper. Then there would remain only the task of blasting the great, shining ship out into the carefully-calculated orbit that would be its home. Out there, away from the muffling, distorting, damnable blanket of atmosphere, away from Earth's inexorable gravitational pull, would be a laboratory such as man had never seen. NO COMMUNICATION FROM ANTARCTICA IN 6 HOURS STRANGE FORCE DEFLECTS PLANES FROM SAHARA AREA WORLD POLICE MOBILIZING The item below the last one said: Pacifica, June 7—The World Police are mobilizing, for the first time in fifty years. "The peoples of the world, then, know what they are, and know that we face the most momentous struggle in our history. "Since the Invaders first appeared in Wood River, Oregon, 24 hours ago, they have not once acknowledged our attempts to communicate, or in any way taken notice of our existence as reasoning beings. They have treated us precisely as we, in less enlightened days, might have treated a newly-discovered race of lower animals. They have examined us, dissected us, driven us mad, killed us with no discernable provocation; and this is more intolerable than any normal invasion. "I have no fear that the people of Earth will fail to meet this challenge, for there is no alternative. Not only our individual lives are threatened, but our existence as a race. It was only two stories down the moving ramp to Lorelei Cooper's laboratory. Peter took it in fifteen seconds, running, and stumbled to a halt in front of the door marked "Radiation." She gazed at him levelly for a moment, kissed him impulsively, and then walked over to the video panel on the wall and swept a mountain of papers away from in front of it. It was a street scene in the Science City of Manhattan, flooded by the warm spring sunshine. Down on the lowest level, visible past the transport and passenger tubes, the parks and moving ways should have been dotted with colorful, holiday crowds. There were left only two blood-red, malignant monstrosities somehow defiling the air they floated in; and below them, a pitiful huddle of flesh no longer recognizable as human beings.
 There was a slim chance of survial
 Women needed to stay underground for reproduction purposes  There was only room for one passenger in the ship.  There was a slim chance of survial  Lorelei was too afraid to make the journey with him.