"We tap the ions of their charges," he said somberly, "that the sunlight made by day. We're pulling in all the power we can. I wonder if we've drained the aurora of its energy, too."
Riki was silent. Massy gazed, still searching. But he shook his head.
"It could be," he said in a carefully detached voice. "We didn't draw much power by comparison with the amount that came. But the ionization is an ultraviolet effect. Atmospheric gases don't ionize too easily. After all, if the solar constant dropped a very little, it might mean a terrific drop in the ultraviolet part of the spectrum—and that's what makes ions of oxygen and nitrogen and hydrogen and such. The ion-drop could easily be fifty times as great as the drop in the solar constant. And we're drawing power from the little that's left."
Riki stood very still. The cold was horrible. Had there been a wind, it could not have been endured for an instant. But the air was motionless. Yet its coldness was so great that the inside of one's nostrils ached, and the inside of one's chest was aware of chill. Even through the cold-garments there was the feeling as of ice without.
"I'm beginning," said Massy, "to suspect that I'm a fool. Or maybe I'm an optimist. It might be the same thing. I could have guessed that the power we could draw would drop faster than our need for power increased. If we've drained the aurora of its light, we're scraping the bottom of the barrel. And it's a shallower barrel than one would suspect."
There was stillness again. Riki stood mousy-quiet. When she realizes what this means, thought Massy grimly, she won't admire me so much. Her brother's built me up. But I've been a fool, figuring out excuses to hope. She'll see it.
"I think," said Riki quietly, "that you're telling me that after all we can't store up heat to live on, down in the mine."
"We can't," agreed Massy grimly. "Not much, nor long. Not enough to matter."
"So we won't live as long as Ken expects?"
"Not nearly as long," said Massy evenly. "He's hoping we can find out things to be useful back on Lani II. But we'll lose the power we can get from our grid long before even their new grids are useless. We'll have to start using our reserve power a lot sooner. It'll be gone—and us with it—before they're really in straits for living-heat."