The main thing was to make as few head motions as possible. Dan had seen people suddenly erupt with projectile vomiting from merely turning their heads or nodding.

The inspector passed him easily enough and Dan gratefully made his way along the tube corridor that led “down” to the lunar-level wheel. He dumped his bag in the cubbyhole compartment he’d rented for this visit, then prowled along the sloping corridor that ran through the center of the wheel, checking the numbers on each door.

Dr. Kristine Cardenas’s name was neatly printed on a piece of tape stuck above her door number. Dan rapped once, and opened the door.

It was a small office, hardly enough room for the desk and the two plain plastic chairs in front of it. A good-looking young woman sat at the desk: shoulder-length sandy hair, cornflower blue eyes, broad swimmer’s shoulders. She wore an unadorned jumpsuit of pastel yellow; or maybe it had once been brighter, but had faded after many washings.

“I’m looking for Dr. Cardenas,” said Dan. “She’s expecting me. I’m Dan Randolph.”

The young woman smiled up at him and extended her hand. “I’m Kris Cardenas.”

Dan blinked. “You… you’re much too young to be the Dr. Cardenas.” She laughed. Motioning Dan to one of the chairs in front of the desk, she said, “I assure you, Mr. Randolph, that I am indeed the Dr. Cardenas.” Dan looked into those bright blue eyes. “You too, huh? Nanomachines.” She pursed her lips, then admitted, “It was a temptation I couldn’t resist. Besides, what better way to test what nanotechnology can do than to try it on yourself?”

“Like Pasteur injecting himself with the polio vaccine,” Dan said. She gave him a sidelong look. “Your grasp of the history of science is a bit off, but you’ve got the basic idea.”

Dan leaned back in the plastic chair. It creaked a little but accommodated itself to his weight. “Maybe I ought to try them, too,” he said.

“If you don’t have any plans to return to Earth,” Cardenas replied, with a sudden sharpness in her voice.

Dan changed the subject. “I understand you’re working with the Mars exploration program.”

She nodded. “Their budget’s being slashed to the bone. Beyond the bone, actually. If we can’t develop nanos to take over the life-support functions at their bases, they’ll have to close up shop and return to Earth.”

“But if they use nanomachines they won’t be allowed to come back home.”

“Only if they use nanomachines in their own bodies,” Cardenas said, raising a finger to emphasize her point. “The IAA has graciously decided they can be allowed to use nanotechnology to maintain and repair their equipment.” Dan caught the sarcasm in her tone. “I’ll bet the New Morality was thrilled with that decision.”

“They don’t run the entire show. At least, not yet.”

Dan huffed. “Good reason to live off Earth. I’ve always said, When the going gets tough, the tough get going—”

“ — to where the going’s easier,” Cardenas finished for him. “Yes, I’ve heard that.”

“I don’t think I’d be able to live off-Earth forever,” Dan said. “I mean… well, that’s home.”

“Not for me,” Cardenas snapped. “Not for a half a dozen of the Martian explorers, either. They’ve accepted nanomachines. They have no intention of returning to Earth.”

Surprised, Dan said, “I didn’t know that.”

“There hasn’t been much publicity about it. The New Morality and their ilk have a pretty tight grip on the news media.”

Dan studied her face for a long, silent moment. Dr. Cardenas was physically youthful, quite attractive, a Nobel laureate, the leader in her chosen field of study. Yet she seemed so indignant.

“Well, anyway,” he said, “I’m grateful that you’ve taken the time to see me. I know you’re busy.”

She broke into a pleased smile. “Your message seemed kind of…” she fished for a word,”… mysterious. It made me wonder why you wanted to see me in person, rather than by phone.”

Dan grinned back at her. “I’ve found that it’s always easier to discuss matters faceto-face. Phones, mail, even VR meetings, they can’t replace person-to-person contact.”

Cardenas’s smile turned knowing. “It’s more difficult for someone to say ‘no’ to your face.”

“You got me,” Dan replied, raising his hands in mock surrender. “I need your help and I didn’t want to tell you about it long-distance.”

She seemed to relax somewhat. Easing back in her chair, she asked, “So what’s so important that you came up here to see me?”

“Down here. I came in from Selene.”

“What’s your problem? I’ve been so wrapped up with this Mars work that I haven’t been keeping up with current events.”

Dan took in a breath, then started, “You know I’m the head of Astro Manufacturing.”

Cardenas nodded.

“I’ve got a small team ready to build a prototype fusion rocket, using nanomachines.”

“A fusion rocket?”

“We’ve tested small models. The system works. Now we need to build a full-scale prototype and test it. We’re planning a mission to the Asteroid Belt, and—”

“Spacecraft have gone to the Belt on ordinary rockets. Why do you need a fusion system?”

“Those were unmanned vehicles. This mission will carry a crew of four, maybe six.”

“To the Asteroid Belt? Why?”

“To start prospecting for the metals and minerals that the people of Earth need,” Dan said.

Cardenas’s face turned stony. Coldly, she asked, “What are you trying to accomplish, Mr. Randolph?”

“I’m trying to save the Earth. I know that sounds pompous, but if we don’t—”

“I see no reason to save the Earth,” Cardenas said flatly. Dan gaped at her.

“They got themselves into this greenhouse mess. They were warned, but they paid no attention. The politicians, the business leaders, the news media… none of them lifted a finger until it was too late.”

“That’s not entirely true,” Dan said softly, remembering his own struggles to get the world’s leaders to recognize the looming greenhouse cliff before it struck. “True enough,” Cardenas replied. “And then there’s the New Morality and all those other ultraconservative cults. Why do you want to save them?”

“They’re people,” Dan blurted. “Human beings.”

“Let them sink in their own filth,” Cardenas said, her words dripping acid.

“They’ve earned whatever they get.”

“But…” Dan felt completely at sea. “I don’t understand…”

“They exiled me.” She almost snarled the words. “Because I injected nanomachines into my body, they prevented me from returning to Earth. Their fanatics assassinated anyone who spoke in favor of nanotechnology, did you know that?”

Dan shook his head mutely.

“They attacked Moonbase, back before it became Selene. One of their suicide killers blew up Professor Zimmerman in his own lab. And you want me to help them?”

Shocked by her vehemence, Dan mumbled, “But that was years ago…”

“I was there, Mr. Randolph. I saw the mangled bodies. And then, when we won and even the old United Nations had to recognize our independence, those hypocritical ignoramuses passed laws exiling anyone who had accepted nanomachines into her body.”

“I understand that, but—”

“I had a husband,” she went on, blue eyes snapping. “I had two daughters. I have four grandchildren in college that I’ve never touched! Never held them as babies. Never sat down at the same table with them.”

Another woman might have burst into tears, Dan thought. But Cardenas was too furious for that. How the hell can I reach her? he wondered. She seemed to recover herself. Placing both hands on her desktop, she said more mildly, “I’m sorry for the tirade. But I want you to understand why I’m not particularly interested in helping the people of Earth.” Dan replied, “Then how about helping the people of Selene?”

Her chin went up a notch. “What do you mean?”

“A working fusion drive can make it economical to mine hydrates from the carbonaceous asteroids. Even scoop water vapor from comets.” She thought about that for a moment. Then, “Or even scoop fusion fuels from Jupiter, I imagine.”