 Why did Val become so tired during her trek across the desert?
The planet itself was tough enough—barren, desolate, forbidding; enough to stop the most adventurous and dedicated. But no; she blamed it all on me somehow: So we were out walking on the spongy sand of the Martian desert. When Val's tired and overwrought there's no sense in arguing with her. I stopped, slipped out of the geiger harness, and lowered myself ponderously to the ground. She slid down beside me, curled up, and in a moment she was fast asleep, sprawled out on the sands. And that started the chain of events that led Val and me to end up as a madman's prisoners, on Mars. It's a stopgap effort, just to keep things moving until Project Sea-Dredge starts functioning.
 She did not have the technology that enabled Ron to persist
 She did not have the technology that enabled Ron to persist  She became consumed with resentment for having traveled to Mars  She had trouble adjusting to the Martian climate and terrain  Uranium was seeping through her space suit