Disclaimer: All I own here are my ideas. The fantastic world of Doctor Who belongs to someone else, as do the songs of U2 and The Beatles. I'm just playing with the characters, and promise to put everything back where I found it.

Summary: After visiting the Planet of the Ood, Donna needs her faith in humanity restored, so the Doctor takes her to the beginning of Earth's new age of exploration. A story about adventure, sacrifice, and the consequences of a mistimed look, where history is in the future.

Spoilers: The Fires of Pompeii and Planet of the Ood.

New Moon

Chapter 1: Eve

"Are you alright?" the Doctor asked from his seat, lounging with his feet propped up on the console.

"'Course," Donna replied tritely. She was seated against the opposite wall. "Why wouldn't I be?"

"If you say so," the Doctor said skeptically, "but if you keep frowning like that your face will stick that way."

"Will not," Donna replied, rubbing her cheek.

"No," the Doctor admitted, "well, maybe. You never know what we're flying through."

"It's just," Donna sighed finally, standing up, "is that all we have to look forward to, us humans? A civilization built on slavery and a population too complacent to admit it?"

"Not all, no," the Doctor replied carefully, getting to his feet as well.

"But that's part of it," Donna lamented.

"Sure," the Doctor admitted, turning a knob on the console. "You humans make a lot of mistakes, you do a lot of terrible things, and you do a lot of great things. That's just part of being human."

He reached for a button beside him then hesitated.

"I wish it didn't have to be," Donna maintained.

"I suppose I've shown you too many of the terrible things," the Doctor said inwardly, and slapped his hand down on the button. The TARDIS shivered. "Grab a coat," he added aloud, pulling on his own and bounding for the door.

"We just went to a cold place," Donna complained, grabbing her coat off a pillar and following anyway. "I was hoping for a beach."

"Watch your step," the Doctor added, as though Donna hadn't spoken, opening the door and stepping outside.

"What for?" Donna asked, pausing at the doorway. "I don't see anything to trip over."

In truth, she couldn't see much of anything at all; the room outside the TARDIS seemed to consist mostly of shadows.

"Come on," the Doctor called from one of them.

Donna stepped off the TARDIS and immediately realized what the Doctor had meant.

"The gravity's different," Donna said in awe, trying an experimental jump which nearly propelled her to the ceiling. "Where are we?"

"See for yourself," the Doctor replied, gesturing to a window behind him.

Donna stepped clumsily over to it, looked outside, and was uncharacteristically lost for words. The view above was a blue marbled planet, the Earth, meaning that the shadowed grey landscape below could only be one place.

"We are not on the moon," Donna breathed, pressing her face against the thick plastic.

"I know it's dark out there," the Doctor replied from the other side of the room, "but if you look closely I think you'll find that we are."

"We can't be," Donna denied.

"Can too," the Doctor countered. "Welcome to Shackleton Crater and Earth's first lunar outpost."

"No way," Donna exclaimed, awestruck. "What year is it?"

"2020," the Doctor replied. He was inspecting the many cabinets arranged around the walls.

"That's not so far off," Donna said.

"Amazing what you humans can do in a couple of years," the Doctor confirmed. Now he was standing next to her, examining a pressure suit, which was standing in a case against the wall.

"Why doesn't someone turn on the heat?" Donna muttered, pulling her coat tighter around her.

The TARDIS was in the center of the room, which was the only place in the domed capsule tall enough to accommodate its height. The room itself seemed to be dedicated to science. The cabinets were filled with beakers and microscopes and several collapsible tables were piled near one side, but it was entirely unoccupied except for the two visitors, and the only experiment currently in progress consisted of a dense assembly of plants lit by a few dim fluorescent bulbs, the room's sole light source.

Donna was about to ask if the outpost was abandoned when she heard a sound.

"Shush," she commanded hurriedly, earning a silent look of reproach from the Doctor, who hadn't been making much noise in the first place. However, his expression slid into a smile when he heard the same thing that had caught Donna's attention.

"This way," he said, locating a hatch and leading the way through it and into a short, circular tunnel.

They emerged in a second, smaller dome, with bunks straight ahead, exercise equipment to the left, something which might have passed for a kitchen to the right, and a pair of socked feet sticking out from and enclosed area between the bunks and the kitchen.

"Haven't seen you in quite awhile," said a female voice, causing both the Doctor and Donna a scare, until she continued and they realized that she'd been singing.

"I was down the hold just passing time."

They approached the socks to find them attached to two legs which were visible up to the knees, but the rest of her was buried beneath and behind a panel next to a toilet. Occasionally the clank of a tool could be heard over her singing.

"Last time we met was a low-lit room, we were…we were…"

The voice faltered.

"We were as close together as a bride and groom," Donna supplied obligingly.

"We ate the food," the voice continued, one socked foot twitching slightly in time with the song, "we drank the wine, everybody having a good time except you, you were talking about the end of the world."

"U2's great," Donna said, a bit louder.

This time the woman seemed to appreciate the interjection for what it was and began the apparently involved process of extracting herself from the place where she'd been working. When was finally free, she bounced to her feet and eyed the two visitors with confusion.

"Hi," she began experimentally. She pulled off a cap and tossed it onto a pile of tools at her feet. The hair beneath was pulled back, but more blonde than brown. She was wearing grey sweatpants and a sweatshirt, but neither was quite baggy enough to hide her frame. She looked as though she might once have been well muscled, but had recently lost most of it, and replaced it with nothing.

"Hello," the Doctor replied enthusiastically, grabbing her hand and shaking it, smiling hugely. "I'm the Doctor and this is Donna Noble."

"I'm Sam, well, Samantha…Farfield, but, Sam," the woman replied, still recovering from the shock of finding two strangers in her outpost. Her accent was American. When the Doctor released her, her hand crept to a small box strapped at her hip, a radio, but she changed her mind at the last second and edged past them instead to a computer, which was in the kitchen area. Sam pressed a few buttons and her look of confusion deepened.

"Um, how'd you get here?" Sam asked.

"We've got a space ship," Donna replied.

"Actually, I'd already guessed that," Sam said, not unkindly, looking behind her out a window that showed an empty landing range. "What I really meant was…where'd you park?"

"In the other room," the Doctor replied.

"What?" Sam asked with the air of one whose intellect was in conflict with her senses, and without another word she dashed off toward the hatch and slid through feet first without touching the floor or walls. Donna and the Doctor followed, more clumsily.

When they arrived in the science bay, Sam had turned on a dim light but was still standing near the hatch with one hand on a wall but her attention on the TARDIS. It seemed that the unexpected appearance of a police box in her outpost was enough to make her realize that the evidence was pointing away from the possibility of it breaking the outpost in order to get there.

"That's your spaceship?" Sam breathed.

"Don't knock it," the Doctor defended automatically.

"I wasn't," Sam replied hurriedly, pulling a flashlight out of her pocket then fumbling through a nearby drawer. "It's just so small. I mean, I had to ride a thing the size of a skyscraper to get here."

Finally, she pulled from the drawer a book of matches. She extracted one, lit it, and blew it out a few seconds later, then started circling the room, watching the movement of the smoke with her flashlight.

"Old fashioned way," the Doctor exclaimed. "I love it."

"Is this what made that noise earlier?" Sam asked as she walked around the room.

"I was wondering if you'd heard that," the Doctor replied.

"I wasn't sure I did," Sam admitted.

"It's kind of unmistakable," Donna pointed out.

"Except for," Sam paused to thing, then charged on, "my mind's been playing tricks on me." After circuiting the room twice and running through five matches, she put the book away, satisfied that the TARDIS's appearance hadn't caused any damage. However, the way in which she did it led Donna to suspect that Sam was coming to doubt a few other things too.

"We're real," Donna said. "We're here."

"Sorry," Sam replied, "but you're up against Occam's razor here."

"Which one's that?" Donna whispered to the Doctor.

"Given multiple equally probable solutions, the simplest one is usually correct," the Doctor explained.

"Well how to we increase our probability," Donna asked.

However, the Doctor was prevented from replying by Sam, who held up a finger for silence and touched a button on her radio.

"Copy that Houston, stand by," she said, then, releasing the button, she looked at the Doctor and Donna and said, "Do you want me to tell the people on the ground that you're here?"

The Doctor thought about it for a moment then said, "I know this doesn't help our chances, but it's probably best to keep all this to ourselves for now."

"You're lucky I had the cameras turned off," Sam muttered as she turned to face the wall behind her, which was covered in displays, knobs, and switches. She then returned to the radio and said, "Houston, I confirm your reading of 1000 ppm."

There was a few seconds of silence then Sam said, "Negative Houston, I was having some trouble with a component and decided to jump on the bike to clear my head."

Sam paused a few moments to listen and turned a few knobs on the control panel, then said, "Thanks, Marley. I'll let you know. Odyssey out."

"Sorry about that," Sam added, turning back to the Doctor and Donna.

"Is there a problem?" the Doctor asked.

"No," Sam replied. "MOCR noticed the carbon dioxide was a little high. They thought it might be a problem with the scrubbers, but really it's just because you two are here. Plus, that trick with the matches didn't help much either."

"Sorry," Donna interjected, "we'll try not to breathe so much."

"Don't worry about it," Sam said. "I adjusted the scrubbers; the levels should go back to normal, though if you wouldn't mind standing a bit closer to the plants…"

Donna began to obey the request, but then paused and said, "You sound like you believe we're here now."

"It's getting more likely. It was MOCR who noticed the carbon dioxide levels, not me, and that match trick wouldn't have been enough to do it," Sam replied. "Plus, if this was a hallucination, since I'm aware of it, I should have been able to find a flaw in it by now."

"That's good," Donna said.

"It would still be nice to get independent confirmation, though," Sam added. "But if you don't want me to tell anyone you're here…"

"Do what you think is best," the Doctor offered.

Sam thought about it for a moment, then, strangely, closed her eyes. Donna was surprised, but the Doctor seemed to know exactly what to do with this development. He reached out and touched her on the shoulder, then, unexpectedly, poked her in the nose.

"What was that for?" Donna demanded as Sam gasped and opened her eyes, rubbing her nose.

"You weren't expecting that, were you?" the Doctor said to Sam.

"All I do is try and think you out of existence, and you come along and hit me in the face," Sam replied, eyes watering, but she was smiling for the first time since they'd met.

"Pretty rude, trying to think two people and a space ship out of existence," the Doctor countered.

"It's not so polite to show up in a person's outpost, unexpected and unannounced," Sam replied. "Anyway, you've got the benefit of the doubt."

No one chose to speak and the silence quickly became uncomfortable. Sam, as the unwitting host, seemed to be suffering the worst of it. She kept looking from the Doctor to Donna to the TARDIS and back, apparently on the verge of asking a question, but for some reason she held it back.

Uncharacteristically, the Doctor seemed to be in no mood to take charge of the situation. He was wearing an expression of awe and dividing his attention between Sam and the control panel behind her. Eventually, Donna simply broke the silence herself, even though she didn't actually have much to contribute.

"So, you like U2?"

"Did you come here for something?" Sam asked in a flood. Though Donna usually heartily protested to being ignored, she was rather grateful that her previous question had been taken rhetorically.

"Doctor, would you care to take that one?" Donna prompted, nudging him with an elbow.

"Yes, right," the Doctor stammered, finally coming out of it, "and well, no, actually, we just figured you could use some company and thought we'd pop round."

"Well, thanks," Sam replied, looking startled, "but is that really all? I mean, we're on the moon, it's not exactly next door."

"Actually," the Doctor pointed out, "it is next door."

"Fine," San admitted, "relativity, everything depends on your perspective. But then Alpha Proxima and the Andromeda galaxy are next door too, and that doesn't make it any easier to get there."

"Well," the Doctor said, looking like he was about to launch into one of his incomprehensible lectures, but Sam stopped him first.

"Then again, you've got a spaceship, which looks like it's made of wood, but can go through walls."

"You're really having trouble with that, aren't you," the Doctor replied.

"I've got colleagues planetside who are physics geniuses," Sam explained. "They've calculated the probability of something spontaneously disappearing in one room and appearing in another."

"Really?" Donna asked, looking skeptical.

"That was about two months worth of lunch hours," Sam said. "JPL isn't exactly known for its hip employees. Anyway, I've seen their results, and that probability is mighty slim, turns out."

"Yes, well, the odds increase dramatically when you're trying to do it on purpose," the Doctor replied, beginning to look disappointed.

"A trillion trillion trillion billion times cubes?" Sam asked pointedly. "I doubt it."

"You're saying you think it's impossible," the Doctor sighed.

"I'm saying that physics as I know it doesn't allow this," San replied, "but there's plenty of physics that I don't understand. Besides, it can't be impossible, I'm looking right at it, and that makes your ship amazing."

"You think?" the Doctor said, brightening.

"Well, yeah," Sam said. "I mean, it must take advantage of some laws of physics that no one's ever thought of, so I wouldn't be surprised if it can do more than move through walls. Well, I would be surprised, but not so much intellectually, I suppose."

"Plus," Sam continued, then faltered, smiling uncomfortably, "this sounds ridiculous to ask because you look human and sound like you're from England, but you're not, are you?"

"Donna is, I'm not," the Doctor replied. "I'm a Time Lord."

"Wow," Sam breathed.

"Would you like a look?" the Doctor offered, "inside the TARDIS? The ship?"

Sam hesitated, glancing toward the hatch which led back to the place where she'd been working, but only for a moment.

"Do you really have to ask?" she concluded, beaming.

Sam lead the way to the door of the TARDIS, with the Doctor and Donna trailing along behind. Now that she wasn't moving so quickly, it was possible to discern that Sam wasn't walking. Instead, she moved with a graceful sashay which propelled her more forward than up. The Doctor and Donna copied her, finding it a much more useful method of locomotion in the moon's reduced gravity.

However, soon all of Sam's grace left her. A polite visitor, Sam curbed her enthusiasm long enough to allow the Doctor and Donna on board first, then skipped in behind them and promptly collapsed. The Doctor was just barely quick enough to catch her.

"Artificial gravity," Sam inferred.

"Sorry," the Doctor replied, setting her back on her feet. "I probably should have warned you about that."

"Is this normal Earth gravity?" Sam asked. Her knees were buckling, so she grabbed the nearby railing with one hand. The Doctor still had her other arm by the elbow.

"9.81 meters per second squared," the Doctor confirmed.

"Damn," Sam muttered. "I've got to work out more. I can't be like this when I get back to Earth."

The Doctor released Sam and turned away so quickly that she nearly toppled over again, but she managed to catch herself.

"How long have you been here?" Donna asked, watching as Sam took a few experimental steps, one hand hovering just over the railing.

"Almost a month," Sam replied, finally declaring herself recovered and turning her attention back to the TARDIS. "Bigger on the inside," she breathed.

"Where are the rest of your crewmates?" Donna pressed.

"Back on Earth," Sam replied, approaching the console, which the Doctor was contemplating. "They left a week and a half ago."

"They left you here alone?" Donna demanded.

"It wasn't exactly plan A," Sam replied, eying the glowing cylinder above the console with her hands clasped behind her back.

"Why, though?" Donna pressed. "I've never heard of NASA sending people on missions by themselves."

"The Mercury astronauts flew solo, the Apollo command module pilots were by themselves for days while their crew mates walked on the moon, and there were dozens of solo spacewalks during the shuttle program," Sam corrected. "It's never a first choice, but sometimes it's the way it has to be."

"Fine," Donna conceded, "but you've got to admit this is a little different."

"The outpost is in shadow," the Doctor supplied.

"That's why it's so cold and dark," Sam agreed. "The primary energy source is solar power, but right now there's no sun."

"So what?" Donna demanded. "That space station goes in and out of shadow all the time, no trouble."

"The ISS orbits every 90 minutes, the most time it ever spends in shadow is 35 minutes. This place hasn't seen the sun in a little over a week," Sam explained.

"How can't it?" Donna asked, feeling intellectually outclassed.

"The moon orbits the Earth at exactly the same rate as it rotates," Sam said, "that's why one side is always facing the Earth. Since a lunar day is 28 terran days, most places on the moon spend two weeks of every month in shadow. Here it's just a little better; this outpost is on the wall of a crater near the south pole, it sees the sun for a little less than three weeks at a time."

"Oh," Donna said, almost following.

"Anyway, the point is," Sam continued, "the only energy the outpost is getting is what's reflected off the Earth and from the backup generator. There's barely enough to keep the outpost and me going, it can't support any more people right now. And that's without considering the water supply."

"Then why didn't you leave with the rest of your crew and come back when the sun is out?" Donna asked.

"The outpost is too fragile right now," Sam replied. "Not all of the backups are online, so if something malfunctions someone needs to be here to fix it manually or else the entire outpost could die."

"But then people are going to come back and help you, right?" Donna pleaded, "once there's enough power?"

"No," Sam replied, with the air of one who'd been trying to avoid thinking about the fact. "That was the original plan, but…rocket the size of a skyscraper, remember? It costs too much to bring people here to do it all the time. I can cry uncle and be replaced if I need to, and the flight surgeons can force me back to Earth, but other than that I'll be here, by myself, until the outpost is ready for a permanent crew."

"How long is that supposed to take?" Donna asked apologetically.

"At this rate, three more months," Sam replied, her face a bit too emotionless to be believed. "Speaking of which, it's been nice talking with you, and you can stay awhile if you like, but I really should get back to work."

She turned for the door.

"Wait," the Doctor called just as Sam was about to pull the door open. "Come with us."

Sam froze, caught off guard by the offer, then turned around, looking torn.

"I would really, really like to, she said, gazing around the TARDIS again, "but I can't just leave. I need to keep an eye on the outpost, I've got things to finish, and if MOCR calls and I don't answer they'll start to panic."

"I can take you anywhere you'd like to go, any time you'd like to go," the Doctor added. "Well, mostly," he amended.

"Really? Time too?" Sam replied, forgetting herself. "Even backwards?"

"You know," the Doctor sighed. "Einstein was a bright guy and all, but you really shouldn't go around thinking that he had it all figured out."

"Doesn't stop the twin paradox from being the most convincing method of time travel I've heard yet," Sam replied, "unless you'd care to upstage him."

"I can show you," the Doctor insisted, "and have you back seconds after we leave."

"I'm sorry," Sam said and sounded it, "but I only just met you. It's too important that I stay here. I can't leave it up to chance."

The Doctor faltered, looking extremely disappointed.

"Tell you what," Sam added, looking up at the Doctor. "Since you've got a time machine and all, if the offer still stands, do you think you could look me up when I'm back on Earth again?"

The Doctor's expression didn't change, but it didn't change for a little too long.

"Oh," Sam said, then turned around, opened the door, and left.

"What?" Donna asked. She hadn't been watching quite as carefully, but as soon as she looked at the Doctor's stricken expression she knew exactly what the problem was. "She never makes it back to Earth. She's going to die."