Author's Notes: I would like to thank Susanmartha, MathGirl, Lillehafrue and ArtisticRainey for giving me early feedback on this. Thanks to Ruth H. for betareading and catching my spelling and grammar mistakes (as well as a few plot holes), and to ThatGirlSix, for giving me feedback and a different perspective on the story. This is a Tracy Sister fic, and one I hope will do justice not only to my OC, but to the Tracy family and International Rescue.

For the record: I have not read Joan Verba's 2011 book, Situation: Critical!, which ― as I surmise from the blurb written about it ― is about a similar situation: John Tracy finding a number of asteroids which come into our solar system from outside it posing some danger that International Rescue must respond to. However, my story has been in the works since November 2007 and was written for that year's National Novel Writing Month. So neither of us have copied or plagiarized each other in any sense of the word. Nor have I copied anything from Boomercat's Asteroid One.

Disclaimer: Gerry and Sylvia Anderson created them; ITC/Granada owns them. I'm just writing about them.

Enjoy!
Tikatu

March, 2065 ― Thunderbird Five, in geostationary orbit above the earth

Thunderbird Five hummed and whispered around John Tracy as he pushed his blond hair away from his face and frowned at the images his telescope picked up. It was all still very new, but he'd already learned to tune out the multitude of voices picked up by Five's sensitive antennae. He'd set the new telescope to taking some clearer pictures of the dwarf planet Pluto and its recently discovered fifth moon. Being as far away from Earth as he was made space photography particularly effective. Besides, he was having fun playing with his new toy.

However, something occluded the telescopic images. He ran a series of diagnostics first, making sure there were no flaws in the telescope itself. When the tests came up clean, he started a continuous scan for whatever it was. It didn't seem big not yet but a week's worth of data proved it to be moving. He wanted to get a good picture of the thing itself, but for some reason it wasn't reflecting the sun's light as much as other heavenly bodies did. As a result, trying to pin it down was proving difficult.

He kept looking for it until his month-long tour of duty was over and he returned home to the tropical paradise that was Tracy Island. His last instructions to his brother Alan were to leave the scanning program running unless there was urgent need for processing space. He'd link to the computer himself in a week or so to pull the results. Not nearly as interested in the astrodome as his brother was, Alan readily agreed.

During the week after his arrival back home, John was caught up in a rescue, one with physical repercussions that put his research out of his mind for a while. Once he regained consciousness and was released from the sick room, it was still a few days before he remembered to download the running data. What he saw made him call in Brains for a conference.

"What do you think?" he asked as the two of them pored over the images.

The slight scientist shook his head. "Ah, I don't know. There's something, uh, there, but it's still not very clear."

"There seems to be more than one of them, and they're moving deeper into the system fairly quickly." John glanced at his friend. "Do you think they could be ... space craft?"

Brains pushed his glasses back up his nose, then ran a hand through his short brown hair, grimacing. "A-As you well know, there has never been any definitive sign of, uh, intelligent life elsewhere," he said, sounding a bit sarcastic. He held up a finger before John could jump in with a reply. "Though I do admit the, uh, possibility does exist, previous sightings notwithstanding."

A smug, good-humored smile crossed John's face. He and Brains had done a study of twentieth century "alien" sightings to try to dispel or confirm them. For John, it had been a lark, something fun to pass the time between classes at MIT and Harvard. For Brains, it had been a study in confusion. Too many times he had shaken his head and muttered, "How can people believe this?" Their conclusion had been a mixed one: most claims were false, but there were a number that they could neither prove nor disprove. The lack of a solid answer one way or the other had irked them both.

Now the brains behind the Thunderbirds sighed. "I don't think this is your, uh, aliens. It's something far more ... p-prosaic, and perhaps more, uh, dangerous."

His smile fading, John asked, "Dangerous?"

Brains took his glasses off this time and wiped the lenses with a cloth. "It will take some, uh, time and much more observation before we can run the, uh, equations. When you return to Thunderbird Five, please keep me, uh, a-apprised of what data you collect."

"Sure, I'll do that."

On his return to Thunderbird Five, John got into the habit of letting the program run during work hours and saving, then downloading the data to Brains. He was really on duty around the clock but had a regular daily schedule with working and sleeping times. During his off hours, he pored over what the telescope detected, beginning the equations that would determine the velocity of the objects and, most importantly, their projected path through the solar system. He also held carefully guarded computer conversations and correspondence with other astronomers he knew, trying to discover if anyone had mentioned seeing the phenomenon. It was abundantly clear that this was no malfunction; it was real and heading deeper into the solar system every day.

More than two months passed before he heard any public discussion on the intruders. By this time, he and Brains determined their nature and were on the cusp of figuring out where they were headed. The public discussions were free and excited at first, but quickly dwindled to little or nothing. The rapid decline in enthusiasm and frequency puzzled John, and those who were still talking about it did so in guarded emails or private conversations.

"The World Government has taken a position on the matter," Tatiana Rafalko, a Ukrainian astronomer, correspondent, and friend told him in a cautious vidphone conversation. "First, we are told we do not yet have enough data. Then they tell us we must be mistaken. Our observations are faulty; our calculations flawed. Their astronomers have decided there is no danger, no threat." She shook her head in the vidphone screen. "Anyone who persists in disagreeing with their position has suffered for it. They are dismissed as alarmists. There are threats to withdraw funding ... or termination from one's position." With a sad smile, she added, "You are wise to keep your head down and your status amateur, my friend. They will not look at you as closely."

He tried vainly to cover a sudden stab of foreboding with an encouraging smile. "You be careful, you hear? The World Gov's not above playing hardball, and I don't want to lose my favorite Scrabble opponent." When she chuckled, he wagged a finger at her. "Yeah, you're laughing now. You know it was just as hard finding someone who'd play me in Russian as it was for you to find someone to play in English!" His tone grew somber. "Seriously, be careful, moya padruga."

She grinned. 'The World Government? Pah!" She snapped her fingers. "They have nothing on a Russian winter, my friend, but spring is coming. It always comes."

Finally John and Brains completed their complex calculations.

"Are you sure about this?" John asked, a hint of plea in his voice that perhaps they'd been wrong.

Brains nodded, taking his glasses off again to wipe them clean. "Y-Yes. The computer has confirmed it. There is no other, uh, conclusion. N-No matter what the, uh, W-World Government's astronomers think or say ... they are wrong." He sighed heavily. "W-We must tell your father ... and start working on some, uh, counter measures."

John threaded a hand through his hair, a bleak look on his face. He exhaled heavily, letting the air hiss through his teeth, and shook his head. "Damn. Just ... damn."