They gathered in Teddy’s office: the usual group of Teddy, Venkat, Mitch, Annie, and (via teleconference) Bruce, plus Mindy Park from SatCom.
“So,” Teddy said, once Bruce’s call was connected, “how are the Hab crew coming on the booster test?”
“Ready to go on their end,” Venkat said. “Mark completed the procedure we sent him to remove the short-range transmitter on the northern weather station and rewire it to boost its signal. Once he connects power, it’ll transmit for two hours on the battery it has. The transmitter itself will probably melt in less than half an hour. But for as long as it lasts, the signal strength should be good enough for any orbiter on that side of the planet to pick it up.”
“Um, yes,” Mindy Park continued. She was the only person in the room not in a neat suit, and her bloodshot eyes made it obvious she didn’t care what the higher-ups thought of her old Astrocon T-shirt and sweat pants. “On Sol 374 six of our Mars satellites will be in position to track the launch. I finished testing software updates that will let them track the signal and send that data to us. As soon as Dr. Kapoor gives me authorization, I’ll upload the software patches and then go home and go to sleep.”
“Our target time is two hours before sunset,” Venkat continued. “It’s a compromise between the optimal trajectory for a perfect sun intercept and the restrictions of communications. Hermes and Earth both drop below the Hab’s horizon about thirty minutes before sunset. As nice as it would be to have one less piece of space junk to deal with, the important part of the test is to verify the numbers the ponies got when this system was tested on their homeworld.”
“Yes, about that,” Teddy said, picking up a piece of paper. “Did I read this correctly? Six G's of acceleration from the launchpad, rising to a peak of eight and a half G’s after three minutes? For a vehicle that weighed twenty tons, fuel and capsule, at launch?”
“So Starlight Glimmer reported, yes,” Venkat said. “And to be clear, their best estimate is that their world and Earth have the same diameter and gross mineral composition, so their one G is the same as ours. Also, they didn’t get a solid rate of decay for the booster’s effectiveness over distance. Their flight was an orbital launch, and the ship went over the horizon while the boosters were still about eighty percent effective. Again, their estimates.”
“I understand the caveat,” Teddy said. “Now tell me what it means for this launch. One G is nine point eight meters per second squared of acceleration, on Earth, right? So how fast is the test vehicle going to go?”
“Well, there are a lot of differences,” Venkat said. “For one thing, after their last test the ponies decided to restrict the power flow to the boosters, both to lengthen the life of the batteries and to prevent the MAV passengers from being crushed. And for this test, instead of using the fifteen large batteries, they’re only using nine normal batteries. They predict a net force reduction in the booster system of about sixty percent for the test.
“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.
somehow i am reminded of the "catapult" systems talked about in the classic novel "the moon is a harsh mistress"...technically more like a Railgun, using magnetic propulsion to fling small cargo pods from the Moon to Earth. but trying to launch from Earth that way had to deal with atmospheric resistance and heating effects...
- High Flight, John Magee Jr.
Magic can probably manage some kind of inertial dampeners too, once things calm down a bit, then that 30G issue would go away. Satellite launching just became a hobbyist activity though. Equestria's going to need some laws about unauthorized launchings before every single university science club tries to set up its own network. Oy.
9065229 I meant to mention that. Heinlein didn't come up with the idea of rail gun or similar spaceship launch systems. A lot of others used the idea before he got round to it. But in real life, the scale of installation required, issues with orbital inclination adjustment, and the stress on materials made it impractical.
9065237 Sounds familiar.
I wonder if one could create an alcubierre drive with magic, considering that in theory, it could travel at the speed of space, which I don't remember the exact number but its about a couple of millions times the speed of light, considering the great inflation that happened at the beginning of the universe, with the sparkle drive earth could colonize the solar system, and perhaps some part of the galaxy, with an alcubierre drive, we get at the very least, our own supercluster.
This launch system basically makes the ground go "OOGA BOOGA!" at the ship.
And
Team Rocketthe ship goes blasting off again.I hate to be the naysayer, but you can't launch a ship into orbit with this system and that should be blindingly obvious to everyone involved except (maybe) Annie. The vast majority of the difficulty of getting into orbit is lateral momentum, which this system wouldn't help with. This launch system would only cut the delta-v requirements of getting something into orbit by about 10%, which is nice but not nearly the gamechanger the people in the office make it out to be.
OTOH, 20 kilometers per second is nearly double Earth's escape velocity. They couldn't launch a cotton ball into Earth orbit, but they could launch a probe to Jupiter. Just nothing with people on it, because given the power falloff the final velocity would be linked to the acceleration rate. There are other tricks as well one could do with it - like what they mentioned about sending two spaceships rocketing away from each other, which could actually be very useful. Alternately just launching a ship high enough it can use a sparkle drive, at which point it hardly matters whether it's in orbit or not. But it's the kind of thing that would make the people in the office say "this could be useful" and not "this will change everything."
9065298
IIRC it was mentioned that the Sparkle drive was theoretically capable of ftl. Given that it's limited by cycle time of the electronic elements and Humans have much better processors, that could easily happen by combining the two worlds' different techs.
9065334 Not so. The system doesn't push the target straight up. It pushes the target directly away from itself. That means the more the object is downrange, the more that thrust becomes lateral instead of vertical.
Greater refinement of the system, including purpose-built launch gantries, would help with efficiency.
9065334
Well, that will depend, bending space-time against teleporting millions of time a minute, which one will spend more magic in relation to the distance they will travel in a specific timeframe, both will require magic though, I particularly don't like the idea of constant teleports, much less in a free magic environment, I like the idea of my ship not moving at all while space moves us, both could be argued of the amount of danger it represents, perhaps an advantage of a sparkle drive is its simplicity, against an alcubierre drive, so its another topic of discussion.
9065342
It still doesn't work for orbital insertion. An orbit always returns to its origin point; if a ship undergoes its acceleration inside the atmosphere, it's either going to end up on an escape trajectory or it will eventually return back into the atmosphere.
It could increase the delta-v benefit to more than 10%, though.
Then again, maybe I'm misunderstanding how this system works. I thought it was specified that it lost power as the distance between the launcher and the target increased, but in this chapter it's mentioned that the acceleration started at 6gs and peaked at over 8; I have no idea why acceleration would go up if the target isn't using its own thrust (and therefor losing mass from fuel).
9065229
I'm thinking an orbital elevator or tether system might be a good way around that. Of course, our materials science needs a bit of an upgrade to make that happen. In regards to the story, the idea of magical repulsorlift is pretty exciting, too. Unfortunately, it looks like earthlings won't be making their own magic equipment without a certified thaumaturgist (e.g. unicorn).
The only thing I'm getting out of this is, by the time this is over, something is going to channel Team Rocket.
9065036
As it turns out, the ponies did bring a particularly useful bit of kit with them to Mars.
Dragonfly could probably hork up something that would protect the connections and still remain flexible should anything happen to shift them slightly. If she can seal a spacesuit against vacuum, making something watertight should be no challenge. Gas molecules are thousands of times smaller than H2O molecules.
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Yeah, let me point something out. An orbiting pony starship with inter-dimensional 'teleport' drive and one of these repulsor arrays would be able to send shuttlecraft-sized payloads from orbital velocity to effective 'standstill' thus allowing the shuttle to land with nothing more than wings and a good RCS system. Or if you leave out the wings and launch straight down, you have a 7 km/sec railgun firing 20 tonne payloads into targets with the ending kinetic velocity roughly equivalent to a small nuke. Or a 70 km/sec railgun firing 2 tonne projectiles at hardened targets. Or a 700 km/sec railgun firing 200 kilo slugs, all from a starship which doesn't have to dodge incoming missiles when it can just 'blip' into another dimension and pop back out anywhere it wants.
Somebody math-check me please. Friendship is C+ projectiles.
You inspired me to look up John Houbolt.
To parphrase KSP,
Getting to space is easy.
It's staying in space that's hard to do.
Once those are accomplished every thing else is math.
Oh man, something is about to go violently wrong...
9065334
You are correct--some thrust is required to insert into a stable orbit. How much depends on the apoapsis (if any) and the horizontal velocity at that point. However, due to the rocket equation, even a modest reduction in reaction mass results in significant bonus to payload mass (i.e, mass on pad).
Take reducing the approximately 11km/s required for low Earth orbit and, with a magic catapult system, you drop the burn dV to--conservatively--3km/s; and in this example, let's choose a medially-efficient rocket with Isp of 350 seconds, and pad mass of 50 tonnes... we want to know how much payload we get into orbit out of that.
dV = Isp * 9.81 * ln(pad/payload) --> payload = pad / e^(dV/Isp/9.81)
Plain ol' rocket: 50 / e^(11000/350/9.81) == 2.03 tonnes.
With catapult: 50 / e^(3000/350/9.81) == 20.87 tonnes.
The exponential relation works in favor of reduction in reaction mass benefiting payload mass out of proportion. A magic catapult is absolutely a game-changer--it's the Launch Loop without the need for the loop; it's the space gun with a fifty-kilometer barrel made of air and pixie dust.
Hm. You know, if you tweaked the power level just right to get balanced forces, this could also be used for a space-fountain-like space platform.
I don't know minotaur spit about integrals.
Aren't they those funny S shaped symbols or those trees in that one 1984 science fiction novel by Larry Niven.
Ponies in Ringworld or the Smoke Ring would be awesome.
9065464
Yeah, it not being straight up does make this a much bigger boost than I first thought.
Something funny I just realized: Using this device for a normal launch would put whatever you sent up (after final course corrections) into a retrograde orbit. Fortunately this shouldn't be an issue for the Hermes intercept; since it's entering from a solar orbit it can match direction with a retrograde orbit as easily as a prograde one.
Edit: Correction based on the post below this one, it would only be retrograde if the vehicle being launched wasn't burning fuel for a lateral motion (in which case it could be either). If you just launch a dumb object it wouldn't go straight up, but would gradually move retrograde to Earth's rotation because it would be moving at the lateral speed of Earth's rotation at the launch site, but the higher you are above the ground the faster something needs to move to "keep up" with the ground, as it has to trace a larger circle.
9065353 The Equestrian final test was using an actual ship which was burning fuel to get lateral way (which contributed a bit to the G load).
And you're right, an orbital insertion burn would still be needed. But 90% of the energy needed comes from the ground with this system, which is a huge savings on fuel- a real game changer.
9065402 Do not taunt CuddlebugTM.
Increasingly as I read this story, I've been thinking how interesting it would be to have a sequel that addresses pony-human relations, politics, technology and
lovefriendship, as the two societies merge.9065504
I don't know how exciting a sequel would be, though - with the two technologies combined they'd be basically godlike supertech for space travel. It might be fun to get an epilogue with Mark and the Ponies/dragon/changeling meeting up for the launch of the Earth/Equus alliance's first interstellar starship, though.
9065500
Do not taunt Happy Fun CuddlebugTM.
Props to Annie for saying what I've been thinking since I read the plot synopsis.
Also, Earth seems excited to make contact with Equestria, but does Equestria feel the same? Sure, a human revolutionized magic in a single email, but after all the various dangerous universes they've encountered and Amicitas' crew's various perspectives of the savagery of humans living in Free-Forever Universe, is Equestria as excited for negotiations with Earth?
9065504
Absolutely, that has always been my favorite part of any human-pony first contact story.
Now that's humans. Not even close to finished with the first disaster and already preparing the next one.
I might be late to the party on this or vastly over simplifying things, but to me the push-the-ship-into-orbit method almost sounds kina like Project Orion.
Where they used nuclear weapons to propel the ship very, very quickly. So what would happen if they stuck a plate onto and under the ship that acted as the bit that the spell pushes away from? Please use small words when telling me that this would probably fail and kill everyone involved, because I'm very tired and long, complicated words will fry my brain.
9065482
Yes. The trees are so named because they are shaped like the symbols.
As for integrals, heres a little "calculus in a nutshell":
Calculus is about finding two things: The derivative of a function or the integral of a function.
The derivative is another function which tells you how fast the first function is changing at a given point. For example, if you have a function that tells you your position at a given time, then "taking the derivative" will give you a function that will tell you your speed at that same instant (the rate at which your position is changing), and taking the derivative of that will tell you your acceleration (the rate at which your speed is changing).
Integral calculus is about going the other way. (eg. Given the acceleration curve and the speed at a known instant, find the speed curve. Given the speed curve and the position at a known instant, find the position curve.)
What makes that fascinating is that the same relationships described by the math show up in all sorts of other places. For example, integral calculus can also be used to find the area under a curve that's defined by a function.
BetterExplained.com has a free course which really makes it intuitive.
It also has a related article on where Pi comes from.
The gist is that calculus is based on the concept of "As you make some variable bigger and bigger or smaller and smaller, what does the function's value approach?" and then using that to identify "limits" (values we can't calculate directly, such as what a function would output if it were possible to divide by zero or the value you'd get as output if inifinity were a number you could feed in.)
In the case of Pi, calculus comes into play because, mathematically, a circle is a polygon with an infinite number of sides. Cook up a function which tells you something about a polygon with X number of sides, then increase the value of X. The higher the value of X, the more closely you approximate a circle.
as Ken Burnside put it, Friends Don't Let Friends Use Reactionless Drives In Their Universes
REALLY hoping this doesn’t end badly considering how greedy those guys sounded talking about the Sparkle Drive.
9065601
All of these people dedicated their lives to space flight. Why wouldn't they feel ecstatic and greedy when they have the potential to gain a cheap surface to orbit system and engines that turn months long journeys into hours on top of all the other advances magic could bring humanity.
9065352
You got to remember man. The planet's rotating underneath them, so eventually, it will provide some lateral movement, since it's basically a spot on a rotating globe that the probe is pushing away from. Yes, eventually we'd just be going in a straight line, but for that close, with how fast the planet rotates, then no, it's not just going to go straight up in the air.
9065361
Wait....stay with me on this, we just do multiple rings, that are wanting to snap onto eachother, but they're pushed down until there's a click and there's a giant box with a payload on top of it. There's two notches on all of these rings. We apply the spell to a crystal that the rings around, and direct the spell to apply to the outermost ring up. It goes up, and the bottom ring stays on the ground, so as the tower gets taller and taller, and since we need to counter act the planet's movement, we just have thrusters on the object to course correct as it goes up. As it goes up, the rings are pulled apart from their original positions, and move a tad, snapping onto the next notch, and since the bottom's attached to the planet, the rings stay with the rings below them for just enough time for the crystal to pass its acceleration on the ring above the ring it left behind. When it reaches the middle of the tower of rings, there's not enough magic in the crystel to sustain the acceleration anymore, so the thrusters direct it towards the outer reaches of the atmosphere and just push it and make it accelerate in the direction it needs to go. Once the crystal has fallen to the ground, detected by seismic activity meters, you'll know that it's reached as far as it will go, and now you can communicate with the cargo to make sure it's on the straight and narrow as it goes down. Now, have the thrusters on the little box make sure it's counteracting Earth's rotational speed and drop the cargo once a signal is recieved. Tada! Easy space elevator! Man, magic is making all of our problems have very easy solutions. I haven't thought it through totally, but it seems foolproof to me.
9065622
I’m more saying could that greed and way of thinking have this story end in a “not so happy” way as opposed to the original?
9065618
dice-shaped grenade? :P
9065263
Considering the way equestria is doing things, they might just let random ponies launch satellites and "destiny", a very real force in their universe, acts to prevent collisions, or in the event of collisions, prevent death.
Oh Celestia, if they intend to launch space stations like that, wouldn't it begin to affect the earth's orbit and/or rotation? That seems like a bad idea unless you're trying to counteract global warming or something...
9065659
The earth's mass is way too huge to give much of a shit about the forces involved.
How do you math in a forest? With square roots!
9065656
Do you want Kessler syndrome? 'cause that's how you get Kessler syndrome.
I... Yeah, that's about right. I'm pretty sure I learned integrals at one point, too. I am 100% sure I unlearned them not too long after that.
9065632
At geostationay orbit, the Angular velocity is teh same as teh Earths rotation speed, so the object appears to be above the same point on the surface. But the orbital velocity falls with distance, so at some higher point the orbital velocity will be the same as the surfaces Lateral velocity, meaning if you can extremely quickly lift to that point or withut lateral acceleration, then the object will be in orit at the peak, if verticle acceleration is deactivated and the launch sites on the equator, or with a little extra push it will be moving faster than orbital speed and so climb higher. Given the gravity tramline between Earth and Moon, its likely in orbit around that which isnt that much delta V from the Earth Sun Lagrange collection which isnt that much energetically diffrent from system wide Lagrange network.
And the auto tracking thing? Phase Conjugation Tracking.
Earliest Google seems to look is about 2007, but I remember the image from a general publication article from long before the 2000s. Although looking up images brings up a shed loads of frootloops that uses words that Ive been seeing in serious science articles for decades then adding, for pain relief, in classic Flim Flam snakeoil sales pitch.
Ah, there we go, early 1980s which is why I wouldve seen it in University. Optically Pumped Titanium Niobate Crystals and Green Light?
Currently, the main bet is that triggering the launch drive, is thruster magic, which is the same as what Mars has previously badly reacted to, and the Winnybago etc is not only unsecured, but they have very little time for erepairrs, never mind rebuilds.
What ever could go wrong?
9065402
Shut up and take my money!
Revolutionary technology so impressive that I almost expected Teddy to start laughing maniacally by the end of his speech.
9065669
Sorry, I couldn't find a square root. Here's a cube root. Better, right?
qph.fs.quoracdn.net/main-qimg-e6082b4b27bc990d5c5b5a95dd7ed7a6-c
9065557
As I understand it, they're pushing against the planet, and move because the planet's inclined to stay still, and they're not attached to the planet, and something's got to move. If they first attach themselves to the planet, then launch, they'll be like one of those children on leashes: spending a lot of energy to just keep the leash taut. That doesn't change when they attach a plate to their rear. They would sit there with the plate sticking out as far as its attachments would let it go.