The Hundred Gram Mission

by Navin Weeraratne

  "That doesn't make your argument. What else would those shipyards be making, bombs? The refugee orbitals are an excuse, it keeps the Space Arms Race pleasant. Within 48 hours, any of those shipyards could be building anti-satellite weapons. That's the whole point of them."

  "So then, whether they build orbitals or interstellar ships, what does it matter? They want to develop their military shipyards, without pissing off each other. It's an arms control issue. We point out that rather than cosmetic orbitals, they do an interstellar program. We offer them real benefits."

  "Real benefits? Like what?"

  "Like giving people hope."

  Sam laughed. "Hope? Who needs hope?"

  "Hopeful people don't go extremist. A Centauri mission will create hope for all peoples, around the world."

  "Orbitals create hope. Your number comes up, and you’re out of the slums. Only one in a thousand go, but hope keeps the rest from rioting. Off to somewhere with more space and food. There are no minorities to fight with. There’s just one language, one religion, one caste."

  Daryl threw up his hands, "Christ, what makes you call that hope?"

  "Have you met these people, Daryl? Your typical climate refugee is not big on middle class values. People learn to spell or to hate. They only rarely do both. If you try to force your values on them, they push back violently."

  "Well I can’t accept that."

  "Well, you have to. This ship is a dream of a better era. People will support this Daryl, lots of people. But you can’t expect the whole world to get behind it. Only the rich, or those lucky enough to be born in a prosperous nation, will support this. People like us."

  "Us? So you support this?"

  "No, of course not. I think it’s a bad idea, that literally won’t fly. However, that doesn’t mean I don’t think it’s a nice idea. It’s what our grandparents promised, and our parents failed. It's not creating hope, it's renewing it."

  "So you do like it?"

  "I like to hate it, yes. But you’re my boss, and I like your money. So if I can't dissuade you from a dumb idea, I'll just get paid to help you with it."

  "Thanks?"

  "I have one last question for you. This is a doozy. It's a moral question. Are you ready?"

  "Hit me between the eyes."

  "The orbitals do help some people. If you succeed, you're going to be denying them. Are you okay with that?"

  "Oh God yes, fuck those losers."

  Snyder frowned. "Is that your final answer?"

  "Look, I get it. Desperate people need hope. But they're not the only people in the world."

  "Those people are competing with you, for resources. It's your dream, or their lives. You don't think you're being callous here?"

  "I don’t resent those people, I feel for them, Sam."

  "Uhuh?"

  "But without something to hope for, I would start to resent them. I think my attitude speaks for many."

  "Oh you're good. Alright, tomorrow, I’ll call you up and see if you still feel this way. If you do, I’ll start working on this."

  Spektorov sat back and smiled. "I’m glad you’re onboard with this."

  "We’ll see what you say tomorrow. I want you to have a good think. Would you do that for me?"

  "I will."

  "That’s all I can ask."

  "Do you want to meet the team?"

  "The designers of this – what’s it called?"

  "We’ve been calling it the Pathfinder."

  "Yes, let’s go meet them. Maybe at least I can talk them out of that stupid name."

  Jansen Henrikson, II

  2051, Alexander Graham Bell Orbital, Low Earth Orbit

  "The single biggest problem of interstellar travel, is propulsion."

  Spektorov looked around the room. The scientists were well dressed, three had obviously had haircuts that very morning. Their faces were reflected in the polished, wooden, boardroom table. Pale, tense, smiling when they thought someone was looking.

  Sam Snyder leaned forward, jacket off and sleeves rolled up. He looked like he was campaigning for office in a folksy town.

  "Propulsion determines everything. What can be sent, done, even when the mission happens," Doctor Henrikson waved his presentation from his tablet, to the huge wall display. "We’ve assumed that the mission must quick. Results must come in as small a window as possible."

  "Why?" asked Sam. "Seems like rushing."

  "It is," the grey haired doctor nodded. "But do you trust Washington not to pull the plug after a few years? How about the UN? The shorter the mission, the lower the political risk."

  "Political risk?" asked Spektorov. "What about other risks? Doesn’t favoring speed cost us in other areas?"

  "Engineering problems," Henrikson waved his hand dismissively. "We can handle those. What we can’t handle are policy makers. If you want a Centauri shot, this is how it has to be. Otherwise, you put the mission at the mercy of people you can’t control. I learned that the hard way, at ESA."

  "Alright," replied Spektorov. "Fast as possible. Like jocks in dark corners, at Prom. Where does that lead?"

  "To the most powerful and efficient engines, possible."

  "Nuclear?" asked Sam. "That's right, I’ve done my reading."

  "Fission and fusion can indeed get us there," Henrikson nodded slowly, "in principle."

  "In principle?"

  "Yes. They’re just too inefficient."

  "You worried about cost?" asked Spektorov.

  "Partly."

  "Doctor, however you cut this, it’s going to cost a lot anyway."

  "We understand, but high cost and engineering problems often intersect. Fission and fusion gives up less than a percent of their fuel’s energy."

  "So?" said Sam. "Sorry, I’m lost. I’m just the reluctant lawyer."

  "Mr. Synder, I understand you drive a gas-powered car, yes?" asked Henrikson, taking off his glasses. They powered down.

  "Well, yes."

  "Sorry, I didn’t mean it as a criticism. The heavier your car, the more liquefied gas you would need to get to work, yes?"

  "Yes."

  "But when you tank up, do you wonder about how much weight, the gas itself adds?"

  "What? No!"

  "Exactly. What goes into your tank weighs so little, you don’t even consider it. But what if you needed to drive across to the East Coast, and there were no gas or charging stations on the way. You’d have to take all your gas with you. Maybe get a trailer with some tanks."

  "Okay. Sorry, I still don't see your point."

  Henrikson smiled. "Doesn’t the trailer add weight? Are you getting the same mileage, pulling all that fuel, behind you? Aren’t you using more gas, just to pull along gas?"

  Sam was no fool. "So a nuclear Pathfinder would be burdened with its own fuel?"

  "A fission or fusion Pathfinder would be burdened. The mission would be possible, Mr. Snyder. It just wouldn’t be practical. The ship would be a monster, and I don’t want to design a monster anymore than anyone else will want to pay for one. What is practical, is using antimatter."

  Spektorov cleared his throat. All eyes went to him.

  "Doctor, isn't antimatter fuel a 100% efficient? Cause I've been looking through your group’s notes, and it seems you guys can't decide."

  "Yes, most people think it's 100% efficient. It is when an electron meets its own anti-particle, the positron. But, this is not the case with all antimatter. For example, when an antiproton meets a proton. Then, only part of that system becomes energy. The rest, becomes other particles.[xx]"

  "So we want the first case? 100% conversion into energy?" asked Sam.

  "No. Full conversion is a bad idea, because energy isn’t the same thing as thrust. We want better efficiency from the fuel, sure. But we also need something coming out the exhaust for the ship to push against.

  "With total conversion, you just get gamma rays. They’re high energy and go in all directions. You can’t really deflect them either –not practical
ly. And if you did, the ship would soak most of it, as heat."[xxi]

  "So let me review here," said Spektorov. "Fission and fusion can do the job, but are too inefficient. Antimatter can too, but is too efficient?"

  "Essentially. However, different engine designs give different results. We simply need an engine that balances efficiency and thrust."

  "Is there such a design?" asked Spektorov.

  "As a matter of fact, yes. Remember I said with protons-antiprotons, you get mostly particles?"

  "Sure," lied Sam.

  "That’s what the ‘beamed core’ design[xxii] uses. The collisions create charged particles, among others. A powerful magnetic field pushes the opposite, charged particles, out as exhaust. These particles leave at close to light speed. The process is ten times more fuel efficient than fusion."

  He pulled up a new slide of an engine diagram. Colored field lines and moving arrows showed flow. "Gentlemen, this is the beamed core rocket. The best efficiency and the best thrust, for the Pathfinder mission."

  The other scientists and engineers smiled, as did Henrikson. Someone started to clap, but stopped when no one joined.

  Sam made a face.

  "Really? I’m not impressed. You want us to fund an engine that’s never been made? With a fuel that needs explaining?"

  The team lost their smiles.

  "Why are you bothering with fuel at all?" Sam continued. "You could just use a light sail. Build and operate a laser beaming station near the sun. It could run for a few months and then you’re done. Light sail tech already exists, and it's getting cheaper. Just yesterday Mitsubishi announced they’ll be putting up a commercial beaming station."

  "Mr Snyder, you have done your reading," Henrikson smiled and nodded appreciatively. "But how big do you think a light sail would need to be to get to Alpha Centauri?"

  "I don’t know. Big?"

  "Huuuge?" ventured Spektorov.

  "Certainly. Let’s say the a probe that weighs a metric ton. Now, a tenth of light speed is the fastest we can safely go. Faster, and collisions with interstellar dust and gas become too dangerous. At this speed it’s a forty year trip. With me so far?"

  "Go on."

  "That sail would have to be four kilometers in diameter. The beaming station’s output would have to be sixty five gigawatts.[xxiii] Gigawatts, Mr. Snyder. And that’s just a flyby, it wouldn’t stop."

  "It can't?"

  "Not without another beaming station at Alpha Centauri, to slow it down. Well, it is possible to slow it down, using only a laser from Earth. But the sail would need to split into two. And your energy needs would go into the hundreds of terawatts. Thousands if you want to send a bigger mission. The world uses about 20 terawatts, a year.[xxiv]"

  "You worked out those numbers?" asked Sam.

  "No, but I’ve done my reading too, Mr. Snyder. These are Robert Forward’s numbers from back in the 1980s. People have been trying to solve these problems a lot longer than we have. You are correct, light sailing is an old and mature technology. Also, the engineering is much simpler than what we’re proposing."

  "If it's still somehow simpler, then isn't it the way to go?" asked Spektorov.

  "The problem is the time window. A beamed core rocket needs a window long enough to get underway. That's it. After that, politics becomes irrelevant. The rocket will arrive, whether or not Earth cares. With light sailing though, long term support is critical. Someone needs to flip the switch on the second station, forty years later. Someone needs to build the second station. Will they succeed? The second laser could destroy countries. Do you think it's existence would be tolerated? We can’t guarantee that. No one can. That’s why we ruled it out."

  "So is that it, then?" asked Spektorov. "We need to build a beamed core rocket?"

  "Later. We need make antimatter first, specifically antiprotons."

  "And how do we do that?" asked Spektorov.

  "There are all kinds of ways, all of them terrible. We even considered harvesting antiprotons from the magnetospheres of gas giants.[xxv] What we kept coming back to, were particle accelerators."

  "Like CERN?" asked Spektorov.

  "Yes. They create antimatter as a byproduct. Not much though: CERN will produce a gram – in a hundred billion years. However, an accelerator can be custom-built to produce more antiprotons. For best results, we want to smash heavy metal ions –Lead, Thorium, ideally Uranium."

  Bad things happen when you collide Uranium," said Spektorov.

  "Only if you want it to. The colliders would be small – just a hundred meters in diameter. Antimatter production would be massive. As much as a gram a week.[xxvi]"

  "That doesn’t sound like a lot, Doctor."

  The scientists exchanged knowing looks and one giggled. "Mr. Spektorov, one gram of antimatter is an unheard of amount. An amount as powerful as forty kilotons of TNT.[xxvii] That’s twice what we dropped on Nagasaki. Sun Star Mining would become a nuclear power."

  Spektorov and Sam sat up, and looked at each other.

  "But is it safe?" asked Sam.

  "Of course not. The nuclear waste produced will be considerable, and deadly. It’s one reason it hasn’t already been done, on Earth."

  "How much Uranium would we need?" asked Spektorov. He turned to Sam, "we can talk to the Department of Energy. I know the Secretary."

  "You will need far more Uranium than the United States will ever give you, or any country for that matter. Uranium is ideal, though more common elements like Thorium or even Lead will do. It will just take longer, and you will need more accelerators."

  "Doctor, how much Uranium?"

  "Depends on the mission. At a tenth of light speed, and then slowing down," Henrikson made scale balancing motions, "right now, we’re estimating a kilo of antimatter, for every kilo of payload. That will change as we do research and develop the technology. Right now, everything is speculative."

  Spektorov looked up, running numbers. Then, the life sagged from his shoulders.

  "But we can still get the Uranium, more than enough of it," Henrikson smiled.

  "No one will give us the quantities needed, you said it yourself," said Sam.

  "That’s because no one has the quantity, that we already have."

  The wall screen hologram changed to a slowly spinning asteroid.

  "This is 2043 QR 3. It is a metal-rich, Near Earth Asteroid. It was visited eight years ago by Sun Star micro probes."

  "Why am I only hearing about 2043, now?" asked Spektorov.

  "Probably because it’s worthless. 2043 was found to be rich in heavy elements, particularly Uranium.[xxviii] No one much cared at the time. The world was switching over to Thorium nuclear and solar power. Uranium was not a growth mineral, on Earth or in space. It still isn't."

  "How much Uranium does it have?"

  "It’s a piece of failed planet, Mr. Spektorov. It's estimated to be between five to fifteen percent, Uranium."

  "I've never heard of anything like this."

  "It's like floating, platinum mountains. No one has found those asteroids yet, but statistically, they exist. It is all you will need for not just one mission, but hundreds. And it already belongs to the company."

  Sam clapped Spektorov on the back, and they grinned like school boys.

  "There are problems, however. While 2043 QR 3 does orbit the Earth, it is a very wide orbit."

  "So? Let's move it," said Spektorov. "We've done it before."

  "With high ice-content asteroids. 2043 has no ice; we would not be able to mine and make rocket fuel on site. It is has almost no volatiles, so we can't even use lasers to steer by flash-boiled geysers. Moving it closer to Earth will not be cost effective."

  "It orbits us, right?" asked Sam. "Why does it matter if it's far away?"

  "Protection of the Earth’s magnetosphere," said Spektorov.

  "Yes," Henrikson nodded. "Without that, it becomes a very dangerous place to live and work. There are currently no orbitals beyond the Earth's magnetosphere, for j
ust this reason."

  "What about underground?" asked Sam. "Just dig a bit."

  "Yes, but the asteroid itself is radioactive, Mr. Snyder. But let’s set this aside. Consider how far away 2043 is. From Earth, there isn’t a Sun Star mine you couldn’t reach in three days. 2043 however, will take twenty days by ion drive."

  "Ion drives can go a lot faster," said Spektorov.

  "An ion drive could get you there in two days, Mr. Spektorov. However, that is not economical. Twenty day assumes a tenth of a pound of thrust. It’s a much more realistic figure. After a three week trip, how long does the engineer stay? It would be too expensive to send him back soon. A year though, would be a good tour. What PhD astronaut would spend a year underground, on hostile 2043? Even if nothing went wrong, they would take a lot of radiation."

  "Money talks, we’ll find people."

  "Can you find a thousand? Now we’re coming to the biggest problem," Henrikson’s shoulders seemed to sag slightly. "The problem of scale. Let’s say the mission is only half a ton - the mass of a compact car. We would need 500 kilograms of antimatter.[xxix] If we built 500 colliders, we would need to run them for five years."

  Sam laughed, it was an evil sound. "So this is the big solution you’ve been building up to, all this time? 500 machines smashing Uranium on a distant, hellish, asteroid? For years? "

  Mr. Snyder," Henrikson began stiffly, "they can be built more economically than you may think."

  "And how is that?"

  "By investing in new technology. Von Neumann machines, specifically."

  "Are you fucking nuts?"

  "Sam, settle down!" Spektorov frowned.

  "No, no, the best of ESA here wants us all to get arrested for doing banned research, and building a weapon of mass destruction."

  "Yes, Mr. Snyder. Banned research."

  "I’m sorry Doctor, am I missing something here?"

  "You are, in fact. Mr. Snyder, we are trying to send an expedition to another star. Immense infrastructure. Technologies that do not exist yet. Unreasonable goals. Did you not think to expect these things?"

  Sam opened his mouth to speak, but Spektorov held up his hand.

  "Mr. Spektorov, if you want enough Uranium colliders, you are going to need Von Neumann machines: devices that build more of themselves. You’ll need them at Centauri too, to build the actual colony. How else can you manage given the cost of even the tiniest payload?" he stopped and put on his glasses. "Both of you, please understand this. Nothing about this mission profile, or any other, works without Von Neumann machines. Nothing. It's like when we went to Mars. The astronauts had to make air and fuel, in situ. Or as when Amundsen went to the South Pole, living off the land while Scott starved."