"But the final test vehicle, according to Mark's measurements, has a mass of 1.62 tons." Venkat smirked as he added, "One point six two is a bit less than twenty. So even with only forty percent of the force on the target vehicle, the test vehicle's going to move a lot faster. If the pony test is accurate, we're estimating a launch acceleration of just under thirty G's."
Mitch lurched up from the couch. Mindy came wide awake. Teddy whistled.
"In English, please?" Annie said.
"A sudden and momentary acceleration of thirty G's causes severe injury in humans," Venkat said. "Sustained, it's lethal in seconds."
"Put it another way," Mitch said, "that rocket engine will be going faster than a civil war cannonball almost the instant it leaves its pad."
"Within about two seconds," Bruce chipped in over the teleconference. "According to Starlight, they expect their battery array to power the system for about seventy seconds. Assuming ideal conditions— a straight vertical trajectory with no divergence due to air resistance— at the end of seventy seconds the target would be going twenty kilometers per second relative to Mars, at an altitude of not quite seven hundred kilometers."
"Twenty kilometers per second," Teddy said quietly.
"That's right," Venkat said. "Our friend at astrodynamics said that doesn't quite get us a direct shot into the sun, but the resulting solar orbit will pass close enough to the sun to turn it into a fairly short-lived comet."
"Twenty kilometers per second," Teddy said again. "No fuel. No engine on the craft. Twenty kilometers per second. In just over a minute." He took a deep breath. "Have we asked the ponies why they haven't used this system before?"
"No, but I can think of several drawbacks from the start," Venkat said. "First, they can't steer the thrust. It just pushes its target away from itself. Second, once they're out of range of the booster, their ship still needs its own engines for steering, orbital adjustments, and the like. Finally, the system requires a planetary mass to rest on, or else you run into serious issues with Newton's Third Law. Try to make one ship push another, and you end up with two vessels getting accelerated apart on varying trajectories."
"Most likely they just never thought of it," Annie said.
Every eye turned to the press director.
"Oh, come on, you fucking geniuses didn't think of that?" she asked. "Look at it. They live in a world so lousy with magic that they barely developed magic batteries until they invented an engine that used magic faster than it could be drawn out of the fucking air. They didn't think, `we can't lift this thing, go get more batteries.' They thought, 'We can't lift this with magic, so let's fart around with a bunch of dangerous explosives and radical new ideas like electronics and radio and shit and see if that works.'
"But then some of them got dropped into our world, where magic is like rainfall in Yuma. And they didn't have any rocket fuel, or electronics, or any of the newfangled shit they were just getting used to, but they got lucky and found enough crystals for a New Age hippie wet dream. So then they thought, `We don't have rockets, but maybe we can use magic.' And so they stumbled across the fucking holy grail of space exploration— cheap, reusable surface to orbit launch— by complete fucking accident."
"How do you create a launch system by accident?" Mitch asked.
"Oh, for fuck's sake," Annie grumbled. "Read your own goddamn history. I have to know ten zillion cutesy little anecdotes about the early manned space program so I can sprinkle them into my bullshit sessions with the press. More than half your major advances in rocket and capsule design almost didn't happen. We were originally going to the moon in a single fifty meter tall tail-lander with an enormous ladder until what's-his-name, Houbolt, jumped over three layers of management to push lunar orbit rendezvous as a fuel-saving mechanism. Because Wehrner von Braun assumed you couldn't rendezvous ships in lunar orbit. Think of how many damn things seem so obvious now, that weren't obvious when our grandparents got all this shit started!"
"Assumptions," Teddy said, nodding. "Thank you, Annie. I think a re-read of some of the books on my shelf is in order." He swiveled in his chair to look at the television screen. "Bruce, what does this mean in practical terms for the MAV?"
"The MAV weighs about twenty-eight tons fully fueled— that's the two ascent stages and the capsule," Bruce said. "With the reduction in force, the boosters will provide an extra three G's at launch, in round numbers— twenty-eight meters per second. A little more than a minute of that would be enough, by itself, to make up the difference between Mars orbit and the velocity required for the Hermes intercept— without a single modification."
"Well!" Mitch flopped backwards onto the couch. "I call that a win! Why not hold the crew back at the Hab a couple more weeks, then?"
"We're still going to lighten the hell out of the MAV," Bruce continued. "The goal is to get onto trajectory with the second ascent stage unignited. That stage can be relit several times, so we can use it for any fine-tuning required to reach Hermes. And even if this test goes perfectly, we can't put perfect faith in this system. After all, the Sparkle Drive had two successful flights before the one that landed our guests in Mark Watney's lap."
Everyone sobered in the face of this obvious truth.
"But the good news is," Venkat added, "we don't need to use the rebuilt Sparkle Drive for the ascent."
"That is good news," Teddy said. "But I want everyone to consider this. If we could duplicate this launch system, and create our own Sparkle Drive, the entire solar system is at our fingertips. If the cave farm can generate enough magic to launch the MAV almost by itself-"
"It could, almost," Bruce agreed. "With steering thrusters, at least. We'd have to choke down more on the velocity to spare the astronauts in the future."
"Then think how much power is generated every second by all the wild plants and animals around the Cape," Teddy continued. "We could launch entire space stations at once— no, entire starships. This technology, or magic, will revolutionize space flight. I cannot stress how vital it is now that we rescue the aliens, establish formal relations with their universe, and learn how to duplicate these systems." He looked around the room and said, "I know you're already doing everything you can for Mark and his friends, but bear in mind the sheer potential they represent. Four years from now we could be going back to Mars, not for another thirty-day mission, but to stay."
No one could say anything to follow that except, of course, goodbye.
Author's Notes:
Yeah. I sat down and did some quick and dirty math. I don't know how to do integrals anymore, if I ever learned, so I made estimates and used a spreadsheet...
... and yeah, the booster system Starlight thought up and Twilight implemented is, well, even more impressive than I thought.
And I'm sure absolutely NOTHING will go wrong with it.
Today's chapter inspired by comments, of course.
Tomorrow's chapter will be the launch.
And, finally, thanks to those who chipped in on the shirt Kickstarter! If you pledged, please check for your survey and answer, so I can make some decisions on production.
Jump to top
Sol 374
View Online
AMICITAS FLIGHT THREE — MISSION DAY 380
ARES III SOL 374
The essential function of a switch is to touch two wires together to complete a circuit— but only when you want them to touch.
By that definition, what Mark had rigged using a small rock, two cables salvaged from Amicitas's discarded engine room, and a long piece of parachute rope too weather-decayed to be put to any more demanding use was a switch... of sorts.
Dragonfly thought it more resembled those box traps that idiot ponies built to capture rabbits (and other things, including changelings). Those things always annoyed her, because (a) they were so blatantly obvious any animal dumb enough to go for the bait deserved to be trapped, and (b) despite being blatantly obvious, they occasionally caught rabbits (and other things, including changelings).
But she had to admit, as dumb as it looked, it worked on paper. One cable, its terminus wire shaped into a hook, had been raised above the other (its wire shaped into a loop) and balanced there on a carefully chosen rock. Any little tug on the rock with the rope would cause the hook cable to slip off and land, hook down, on the loop cable. It didn't have to be a perfect ringer, though that would be ideal; any wire-to-wire contact would do. The system allowed the two of them, Dragonfly and Mark, to be about fifty meters away from the loop, or seventy meters away from the rock cairn built to hold the test vehicle above the enchanted repulsor crystals.
Seventy meters, or as Mark called it, "ten seconds head start."
So long as that hook remained above that loop, the nine batteries powering the launch could be safely switched on with no effect, and this Dragonfly had just finished. "Pad power hot," she reported over the comms. "Repeat, pad is hot. All batteries show full charge. Go for launch."
Mark, for his part, had removed the nosecone and was connecting one vital wire in the small transmitter cannibalized from the north weather station. "Ow!" he grumbled. "That's a strong signal, all right! Transmitter is live. Reattaching nosecone now."
Dragonfly trotted over and burned a little magic to start four of the bolts that kept the nosecone clamped around the reversed neck of the engine bell while Mark started and tightened the fifth. Once that transmitter went live, the clock had started. Pushing enough current through the transmitter to allow it to be tracked by the satellites circling Mars, most of which hadn't been built to track things other than Earth, would overheat the circuits. The Martian cold would only slow that process down slightly. They needed to get done and get out.
"Message sent to Pony Space Agency," Starlight said over the comms. She and Fireball were at the cave, she inside and Fireball just outside. Fireball would film the launch with Mark's hand-held video camera while Starlight, in the cave, would communicate with Equestria.
"Message sent to NASA; about to launch, stand by for data." Cherry Berry and Spitfire were back at the Hab. Cherry Berry stayed in the Hab to communicate with Mark's people (even though, by the time they got the stand-by warning, the launch would be complete). Spitfire sat in the old bridge of Amicitas, running the telepresence spell so that the magic-powered suit comms would reach across the eleven kilometers between the Hab and the flat ground well east of Site Epsilon.
Normally using tools in a spacesuit required care, planning, and patience. A year of being stranded on Mars had made both Mark and Dragonfly a bit blasй about such risks; Dragonfly could patch her suit, and Mark's suit had been built to withstand being used by troll babies with teething problems. The nosecone bolts were snug to a turn in under a minute. "Nosecone secure," Mark reported. "All go for launch. Pad crew now clearing launch area." Slipping the ratchet wrench into the small tool pouch on his suit, he turned to Dragonfly and said, "Engage de-assifying procedure."
Dragonfly liked Mark quite a lot— and not just because he was delicious and generous with his affection to a fault— but he wasn't as funny as he thought he was. "Excuse me?" she asked.
"I said run!" Mars's low gravity couldn't help but cause some muscle atrophy, but enough tone remained in Mark's legs to send him bounding over two meters in a stride at full gallop. Dragonfly, on the other hand, had learned like the ponies to gallop with minimum vertical motion and maximum horizontal motion, so she arrived at the end of the trigger rope in four seconds, leaving Mark to arrive three seconds later.
"Launch crew at trigger station," Dragonfly reported as Mark, having lost his balance in the effort to brake his momentum, picked himself off the regolith and grabbed the loose end of the rope. "Standing by for final go no/go for launch."
"Earth comms are go," Cherry said. "Suit comms?"
"Suit comms go," Spitfire reported.
"Water telegraph?"
"Water telegraph is go, Flight," Starlight reported.
"Ground tracking?"
"Go, Flight," Fireball reported.
"Roger. Satellite tracking is go. Launch systems?"
"Launch system is go, Flight," Dragonfly said.
"Ship systems?"
"We're Go, commander," Mark said.
There was a brief pause.
"Oh. Right. Yes." Cherry Berry continued on, "Command confirms all go for flight. Pad crew may initiate launch at their discretion."
Dragonfly looked at Mark. "How you wanna do this?" she asked.
Mark cleared his throat. "Counting down from ten," he said, squeezing the cracking, somewhat brittle changeling rope in his suit glove. "Nine. Eight. Seven." He carefully got to his feet, leaving enough slack in the rope to avoid a premature launch. "Six. Five. Four." He turned his back to the launch pad, facing the afternoon Martian sun and the flattened lump that was Site Epsilon half an imperial mile away. "Three. Two. One!"
He yanked the rope hard, pulling it taut, and ran with it for several paces. When he heard a rumble of thunder through Mars's tenous atmosphere, he dropped the rope and ran faster, trying to adjust his bipedal gait to better imitate the ponies. A second shadow flickered in front of him, despite the sun shining down.
Dragonfly, meanwhile, passed him like he was standing still, making a beeline for the cave farm's airlock.
Neither one looked back. Safety lay under meters of solid rock, and neither of them was confident enough in what the six of them had built to risk being outside if it came down.
Later on, they watched the video Fireball got, so that they could edit down the first couple of seconds of launch to send to Earth for a precise measurement of how fast the test vehicle left the cairn.
In the end they didn't send the video, because one frame the test vehicle was on the cairn, the next frame the cairn was hidden behind nine beams of brilliant magical light that triggered the automatic safety systems in the camera, and in the third frame the test vehicle and the top layer of rocks on the cairn were gone. The rocks would be found later, having fallen just a bit short of the repulsor spell projectors, caught up in some sort of wake.
Then Fireball had reflexively tracked up, finding the top of the pillar of light and, presumably, the small former rocket engine on top of it. He never actually caught sight of the test vehicle. He did, however, get a perfect shot of the ring of clear air that opened up around the repulsor spell in the wake of the vehicle, the shockwave driving away the fine dust that turned the Martian air pink and leaving a rapidly growing hole in the sky colored a perfect robin's egg blue.
