The bigger the boom, the faster you can go.
The Tsar Bomba was big. I mean, really big. Its fireball alone was five miles in diameter. The cap of the mushroom cloud was up to fifty-nine miles wide and soared up to forty-two miles above the Earth, above the stratosphere into the mesosphere.
We’re gonna need a much bigger boom than that if we’re going to cruise the Solar System in style.
There is something that makes a much bigger boom, but it’s rather nerve-wracking to work with, and accumulating enough of it makes the Manhattan Project look like a couple of toddlers with crayons: antimatter. To give an idea of how powerful antimatter is, to make a boom equal to the Tsar Bomba, take one kilogram each of matter and antimatter, pour them into the Cuisinart, and press “puree”. You won’t know how it turns out, but if you’re in Boston, everybody in New York City sure will.
So…yeah. Good stuff. Tell Dr. Emmett Brown his DeLorean is going the way of the dodo if he doesn’t get with the program and install what all the cool kids have: Mr. Antimatter. Did you know there really is an “Antimatter for Dummies” website? And according to Google, Rule 34 even applies to antimatter. Talk about an explosive org…um, never mind.
Enough with the fun. Now it’s time for us to start getting lost in the weeds.
You surely know what antimatter is, so let’s dispense with the basics like antimatter in bananas, antimatter in modern medicine, and antimatter orbiting the Earth. Besides, all those are byproducts and there’s not enough of it to matter (no pun intended). To colonize the Solar System, we will need to manufacture antimatter and store it.
“Wait, didn’t I read somewhere that we can already make antimatter?” Yes, that’s very true. We can indeed make antimatter — just not very much of it. The three particle accelerators used to do so have combined to make a whopping eighteen nanograms. Yes, that’s “nano”, as in one-billionth. To be sure, we don’t need much:
There’s no question that antimatter is potent stuff, with the potential for dealing out a thousand times the energy of a nuclear fission reaction. Use hydrogen as a working fluid heated up by antimatter and 10 milligrams of antimatter can give you the kick of 120 tonnes of conventional rocket fuel. (source)
Like I said, good stuff. But there’s a bit of a difference between nanograms and milligrams. To give a bit of perspective:
If all the antimatter ever made by humans were annihilated at once, the energy produced wouldn’t even be enough to boil a cup of tea. The problem lies in the efficiency and cost of antimatter production and storage. Making 1 gram of antimatter would require approximately 25 million billion kilowatt-hours of energy and cost over a million billion dollars. (source) (boldface mine)
Remember in the first article the observation that scientists discover the what, the thing that can be done, and engineers invent the how, the way to get it done? Well, a physicist (and science fiction writer) named Robert Forward did describe how ginormous amounts antimatter can be manufactured, even as much as a full gram per day (yes, 1g of antimatter IS a ginormous amount):
At the distance of the Earth from the Sun, the Sun delivers over a kilowatt of energy for each square meter of collector, or a gigawatt (1,000,000,000 watts) per square kilometer. A collector array of one hundred kilometers on a side would provide a power input of ten terawatts (10,000,000,000,000), enough to run a number of antimatter factories at full power, producing a gram of antimatter a day. (source)
This is normally the point where almost any engineer would roll her eyes and say, “Oh, all we need to do is build an array of solar collectors only ten thousand square kilometers in size? In space? Why, that’s no problem at all, Mr. Forward— just take this vintage Nestler 0210 Darmstadt slide rule and shove it up your…”(transmission ends).
Except that now, as described in Part II of this series, spaceborne mining and manufacturing is becoming a thing. In a decade or two, that ten thousand-square mile solar collector array may well be not just possible, but in progress.
Next up in Part IV, we’ll consider the array itself, how it manufactures antimatter, and how the antimatter is captured and stored.