“How is the fit?” asked Twilight, checking the cloth suit that covered Rainbow Dash’s body.

“A bit tight,” said Rainbow Dash. The suit itself was actually only slightly tighter than her spandex Wonderbolt’s uniform, but the fabric was far thicker and stiffer. “It feels way to heavy.”

“You’re gonna need it,” said the Pegasus helping attach her equipment. He was one of the support staff that served the Wonderbolts. His name was Preflight Check, and Rainbow Dash knew him well. He was a critical part of her squad. Although he himself was not an expert fighter, his eye for detail was even better than Twilight’s. His job was to manage the equipment- -wing augmentation, weapons loadout, special gear, and so forth- -a position that had only formed relatively recently with the ever-increasing number of technological toys that were becoming available for the Equestrian Air Force.

“Why?” asked Rainbow Dash.

“Because after two miles up, the air gets cold. Nopony’s gone that high in years. And you’re going to go a lot higher.”

“Rainbow,” said Twilight, helping to insect the gear herself, looking over Preflight Check’s shoulder at ever strap and zipper. “Are you sure you want to go through with this?”

“Um, of course?” said Rainbow Dash, lifting her wings for more equipment to be strapped onto her body. “Nopony else can do it. And besides, I’m always glad to help our- -especially when it means doing something this epic!”

Twilight smiled, but she still looked nervous. She took a deep breath. “To be absolutely honest, Rainbow, this isn’t exactly safe…”

“Don’t worry about it,” said Rainbow Dash. “I mean, who do you think you’re talking to?”

“This isn’t going to be like performing a sonic rainboom,” warned Twilight. “It requires precision timing. But if all my calculations are good…you should be able to pull it off. Now stand very, very still.”

“Why?”

Twilight lowered her horn, and with a glow of purple magic Rainbow Dash suddenly felt strange, as if her skin were pulling close around her. It was an odd and uncomfortable feeling, but it actually made her clothing feel better.

“What was that?” she asked.

“A reinforcing spell,” said Twilight. “Just in case.” She smiled. “Okay. I’m going to admit it- -I’m really excited. If this works, the readings we get could revolutionize the entire field of kinetic magic, and several laws of physics.”

“As long as I get to go fast, I don’t mind all the egg-head stuff.”

“Oh, you’ll be going fast,” said Twilight, her expression of fear returning. “Actually, nopony has gone this fast since the Aurasi.”

“Aura-what?”

“Oh,” Twilight said, seeming not to realize that Rainbow Dash was not well versed in much ancient lore. “They were like Pegasi, but bigger, and made of gold.”

“Gold?” said Rainbow Dash. “Gold is heavy. How did they fly?”

“I have no idea. But they did.”

“And one of them did this quarry Celestia thing?”

“Quantum-celestial acceleration,” corrected Twilight. “That’s what you’re trying to do here. It’s like a sonic rainboom, except instead of going faster than sound, you go faster than light- -which shouldn’t even be possible.”

“And one of these gold-guys did that?” asked Rainbow Dash. She was annoyed that somepony was outdoing here- -even if they had been dead for millions of years.

“Yes. Twice. But for some reason, there’s no eyewitness accounts of it.”

“So let me get this straight,” said Rainbow Dash. “You’re asking me to try to break a speed record set by a golden pony over a million years ago that nopony has ever seen since. Is that what you’re asking me to do?”

“You don’t have to if you don’t want to. In fact, because of the danger, I would recommend- -”
“That. Is so. AWSOME!” ‘

“Stop moving,” said Preflight Check. “Or you are going to get pinched.”

“Sorry,” said Rainbow Dash. “Just really really really really excited!”

“Yeah,” said Preflight Check. “Just be careful. Spitfire and the others are going to be watching- -and a lot of spectators as well. Don’t choke. And if you pull this off- -hay, if you even almost pull this off- -your almost guaranteed a promotion.”

“So. Cool,” whispered Rainbow Dash as her auxiliary air tanks were mounted to her sides, weighing her down even further.

“Rainbow,” said Twilight, once again fully serious. “Please. Please be careful. If you need to bail at any time, sacrifice the experiment, not yourself. Nothing is more important than your life.”

“Wow, Twilight. Come on. If you keep talking like that, I might lose confidence.”

“I’m serious, Rainbow. Test pilots have gotten injured- -badly- -in horizontal flights. And you are going to do a firmament dive. Rainbow, I don’t know what I would do if I lost you…”

“Come on, Twi,” said Rainbow Dash, putting her hoof on her friend’s shoulder. “I’m the best that there is, remember? Look, I promise to come back- -safe, sound, and a full twenty percent more awesome. Here. Just to be sure.”

Before Preflight Check sealed her collar, Rainbow Dash reached into her jacket and removed a thin golden chain. The end of it contained a small flat amulet with the Wonderbolts insignia, as well as another mark indicating Rainbow Dash’s name and rank.

“You’re tags,” said Twilight. “No, I can’t take that- -”

“Relax, Twi. You’re a princess, so I’m pretty sure it’s okay. Besides, I’m going to get them back in a few hours. Right?”

Twilight smiled and took the tags. “Right.”

Rainbow Dash had reviewed the order of steps hundreds of times, but as she approached the runway, she reviewed them again in her mind. The steps themselves were simple, but deliciously insane, even when Twilight managed to explain them in excessively egg-headish detail.

The main element of the task was to perform something called a firmament dive. As Rainbow Dash understood it, the sky- -which she had always imagined as infinite and vast- -had a boundary, an upper limit. That limit was, literally, as high as any pony could ever fly. Rainbow Dash’s first task was to rise to that border, to set hoof upon it- -something that alone would be tremendously important in the history of Pegasi. Just the thought of doing that made her wings tingle with excitement.

That was just the easy part, though. Once she reached it, she was to dive as steep as possible, driving herself forward as rapidly as possible. She would fall back to Equestria, reaching speeds far faster than the rainboom threshold- -and then was expected to turn.

That turn was the reason why she alone could perform this test. She needed to level a dive at supersonic speeds- -something that no other pony would be able to do. The force alone risked tearing her wings off, but she knew that it would be possible- -and even if she failed, Twilight was prepared to teleport her to safety to prevent her from being splattered on the ground.

Once she leveled, she would engage the rockets that were not strapped to her body beneath her wings. They were something Twilight had been working on for months, a kind of magical engine. They had been tested numerous times in horizontal flights, but they proved to be both dangerous and limited. The amount of magic the enchanted crystals within contained could not be dissipated fast enough to make a pony go much faster than the rainboom barrier, and the pony who used them had to be an excellent flier to control the sudden surge of speed.

For a long time, Rainbow Dash had thought that using magic with flight was cheating. It just seemed wrong to use such a thing to tarnish the purity of flying. That was, at least, until she saw the results. Then she had known that magic-assisted flight was the future. The speed and the rush of flying under the power of engines was something that she had never expected, the feeling of flying with a machine roaring beneath her wings. It was still no match for real flying, but it had its own charms.

As she entered the runway, the world seemed to move in slow motion. She could hear her breathing on the inside of her mask, and smell the air pumped in from her oxygen tanks. Looking around, she saw the sight that she had become accustomed to. All around her were spectators, many in the fields around the airstrip, but many in the large airships that surrounded the runway.

Only official personnel were allowed on the runway itself- -as well as her friends, who had been given special authorization for the event.

Rainbow Dash waved to them- -her five core friends, save for Twilight, who was setting up observation equipment with her research team- -and Scootaloo. She then saluted Spitfire, and her comrades who had come to observe.

Even of the noise of all the cheering from the crowds, she heard Fluttershy’s small “yay”, and Pinkie Pie called something out.

“Hey Rainbow Dash!” she yelled. “When you get back, I’ve got a killer party planned! A great big cake for all these ponies!”

“Rainbow?” said Twilight, approaching. Rainbow Dash turned and looked at her friend. “Are you sure?”

“Absolutely. Wouldn’t want to disappoint all my fans, would I?”

“Just be careful. And thank you.”

“No problem. Now, you might want to stand back.”

Twilight stepped back, as did the rest of the crew, and Rainbow Dash paused for a moment, soaking in the pause of cheers as suspense gripped the crowd. Then she spread her wings, and listened to silence fall in the crowd- -then, with her full force, she shot upward. At one hundred feet, a circular jet of rainbow energy poured from around her, bending into the cone shape characteristic of an ascension rainboom.

She knew it had not been necessary. Upward speed had no bearing on the test- -but she did not want to disappoint her fans. That, and, on some level, she was nervous- -and wanted to get to the good part as quickly as possible.

The air rushed past her as she powered forward, watching the clouds separate as she passed them. On the lower ones, some Pegasi were waiting to cheer her on as she rose through the air faster than most ponies could dive, but as she got higher, the clouds got too thin to support Pegasi. At the same time, she felt the air changing. It got thinner, and she had to power her wings faster to keep moving at the same speed. As Preflight Check had predicted, it also became much colder. The suit that surrounded most of her body compensated for some of it, but her wings had to be exposed, and they were starting to ice.

So pushed harder, hoping that there was enough air onboard to sustain her. She had already passed the maximum altitude for most recommended flying as well as her personal record- -but the firmament was still miles away.

It took nearly half an hour for her to begin to move past Equestria’s atmosphere. The sky itself had changed- -now, instead of blue, it looked black, and the horizon between the green and blue world below and the darkness above was becoming visible.

She could feel the heat of the sun- -and see it, far larger than she ever had. Even at a distance of hundreds of miles, it still was powerful enough to instantly melt the ice from her wings. From what she understood, the sun, like the moon, was imbedded inside the firmament. Theoretically, she could have flown to the sun, like the Icarus of legend, but that was already known to be a terrible idea.

Through her mask, Rainbow Dash scanned for the signs of the firmament. She was not entirely sure what she was looking form, but she had been given certain signs. The stars, for example, would be imbedded in it, as were several artificial, unreachable objects that had only recently been discovered- -objects that Twilight suggested were made by someponies called “cerorians”.

Then she saw them. The stars, and the strange, semi-translucent substance that contained them. Up close, they did not look like what she had expected. They were far smaller and far brighter, consisting of looping arcs of Luna’s magic that clung tightly to their backing. Even stranger, they seemed to be watching, as if they somehow had eyes and minds within them.

Rainbow Dash slowed herself, but found, to her astonishment, that the familiar pull to Equestria below had diminished. Instead, when she stopped moving her wings through the impossibly thin air, she simply drifted- -until she struck something somehow solid.

The contact was extremely disorienting. Rainbow Dash found herself standing on what her mind automatically perceived as “grouond”, even though the real ground, Equestria, was now the “sky”. The inversion was nauseating and amazing at the same time.

The texture of the firmament was not pleasant, either. Rainbow Dash had expected something hard, like glass, but instead it was more gelatinous, like thick mud, and she felt her feet sticking as she walked along it.

She suddenly cried out as something moved. To her disbelief, a head suddenly poked out of the firmament- -and she saw a face that, to her greatest annoyance, had become an increasingly common sight in recent years.

The sickly green pony with a single antler-like horn pulled himself out of the firmament until he was only waste deep.

“Oh, hey,” he said. “Don’t bother saying anything. There’s no air up here; sound doesn’t travel. Also, FYI, no, I did not break you record. I’m not a pony. Well, sort of. Mostly. I am butter.” He leaned back, backstroking through the thick firmament aether. “Oh, also, when you get down there, say hi to Brown for me. And tell me he still owes me three bits.”

Rainbow Dash had no idea what he was talking about, but did as she always did when things involved Buttery Snake- -she simply ignored him. She instead took one last look at the firmament, and at the view of Equestria above her- -and did her job.

She released the firmament, and started her descend. At first, she simply drifted- -but then she could feel the force of gravity upon her once again, and used it to guide herself into the steepest dive possible.

She accelerated. She could feel it, even if she could not see it- -the frame of reference was simply too vast, and the air too thin, but by some Pegasus instinct, she knew that she was moving, and moving quickly.

Almost as soon as she started, the air around her shook and ruptured with a rainboom, showering the world below with a rainbow- -but that only signaled Rainbow Dash to move her wings faster, to drive herself down with even greater speed. In a moment of daring, she adjusted her angle- -to a complete vertical.

The air around her shifted again, and she felt a second rainboom pour out of her. She could see Twilight’s magic ignite into a shield around her, burning from the heat of reentry. Even through the shield, she could feel the air passing by her at impossible speed, and she gritted her teeth against the feeling of losing control.

A third rainboom came, and then a forth, and Rainbow Dash felt an indescribable pleasure running through her body. It was the height of adrenaline- -pure fear, and the finest, sharpest form of excitement. It was something she had not felt in years- -and the reason she had been so vehement about assisting Twilight with this particular test.

The air seemed to distort again, but this time, something was different. It was not just the air that was changing- -it was space itself. She realized that, somehow, she was not alone. She glanced to her side, momentarily expecting to see Buttery Snake trying to steal her thunder, but instead gasped as she saw a bizarre ghostly figure descending beside her. It was larger than her, but clearly a pony- -a pony who seemed to be made from plates of gold. He apparently could not see Rainbow Dash, but she could see him- - and how he seemed to be laughing manically.

Then another rainboom occurred, this one large enough to spread a corona of color out over the entire continent- -and Rainbow Dash felt herself accelerating uncontrollably, the force of the rainboom driving her forward even more rapidly.

As she moved faster, the golden figure beside her seemed to notice her, and turned toward her- -revealing that he only had one eye. It was about that time that Rainbow Dash looked down. Her mind reeled as she saw how fast the world was flying up toward her- -and, terrified, realized the true extent of her speed.

She was only seconds away from impact, and she spread her wings. The force was incrediable, and she clenched her jaw as her feathers were torn out. With all her strength, she forced herself out of the dive. The bones in her wings creaked, and then cracked. She knew that if even one of them failed, there would be no escape from the resulting death spiral- -but there was no choice.

Rainbow Dash put her trust in Twilight’s magic, and twisted her wings.

The crowd below must have been treated to an incredible sight as Rainbow Dash fell. They were silent, many fully expecting her to plummet to her death- -but just feet from the ground, Rainbow Dash pulled out of the dive, channeling the force of her downward descend into horizontal motion.

She could not hear the roar of the cheers through the roar of the wind passing her body, and she felt the world starting to go dark. Her flight suit automatically compensated, though, inflating internal sacks to force the blood back to her brain and wings- -and even with fractured wings, she managed to level her flight.

For a moment, she was overjoyed, high on a thrill unlike any she had experienced in her life- -but then she remembered that her work was not done. She reached onto her chest- -not an easy task, considering the force of the wind against her legs- -and activated the magical thrusters.

Her speed instantly quadrupled, and she felt herself being rushed forward, the trees around her blurring into a single green mass. The world itself suddenly burst into flame and energy around her, and she felt her speed change- -as if she were suddenly slowing. She did not know why, or how, but she somehow felt a reason¬- -as if the world were resisting her acceleration, as if the laws of physics themselves did not want her to succeed.

In response, and with a smile, she lowered her wings and head and forced herself forward just slightly faster- -and felt the roar of the universe snapping around her as reality suddenly vanished.