Planning Planets

BROTORO: Tonight on Kerbal Space Program Forum I’d like to welcome our special guest, Mr. Slartibartfast, who has consented to talk to us this evening about solar system design and construction. Thank you very much for being with us today!

SLARTIBARTFAST: Well, I don’t normally do interviews, but when a very important client asked for a representative from the Commercial Council of Magrathea, it happened that I was the only one who’d ever talked to an Earthman, so I got the job. It’s all a bit of a bother, really.

BROTORO: A very important client? Who would this very important client be?

SLARTIBARTFAST: I’m sorry, but we do not disclose information about our clients. They are all very wealthy and powerful beings, and I’m sure you’ll understand that they enjoy their anonymity. But I will say that you’d never have gotten this interview if the Mice were not very big fans of space travel.

BROTORO: Mice are big fans of space travel?

SLARTIBARTFAST: Certainly. Why else would they have arranged to be some of the first passengers ever flown in a rocket? But I’ve said more than enough on that subject already.

BROTORO: Ah. OK, let’s get right to tonight’s topic. Is there any truth to the rumor that Magratheans did the design and construction work for Squad on the Kerbol planetary system?

SLARTIBARTFAST: I’ve already told you, we don’t discuss our clients.

BROTORO: Well then, hypothetically speaking, could you tell us if it’s possible to design a solar system with these specifications?

(BROTORO hands Slartibartfast a sheet of paper. Slartibartfast glances over it briefly.)

SLARTIBARTFAST: Ah, yes... Miniature planets are adorable, aren’t they? They were all the rage with a certain portion of our clientele.

BROTORO: So it’s possible to construct a solar system matching those specifications?

SLARTIBARTFAST: Certainly. We Magratheans pride ourselves on being able to build any kind of planet.

BROTORO: But look at the densities of those planets. Most of them have densities greater than any known element.

SLARTIBARTFAST: That’s not a problem. We use black holes.

BROTORO: Black holes? But wouldn’t a black hole inside a planet just swallow it?

SLARTIBARTFAST: No, no. We use spherical force field bubbles centered around small black holes. We can adjust the mass of the black hole and radius of the force shell to get any planet density desired, then cover it with the mantle and crust material of the client’s choice. It’s a very flexible system.

BROTORO: So you’re saying that Kerbin is mostly hollow inside, with some old rocky material thrown on top?

SLARTIBARTFAST: No. More like the inner one third is hollow. And I assure you we use only the finest ingredients when building our planets.

BROTORO: Wouldn’t these force field bubbles require energy to maintain their structure?

SLARTIBARTFAST: Certainly they require energy. We just allow a small amount of matter from the lower mantle to trickle through openings in the sphere. As the matter falls into the gravity well of the black hole, the energy equivalent to a sizable fraction of its rest mass is released as radiation before it crosses the event horizon. That radiated energy is captured and used by the force field bubble, which also acts as a Dyson sphere.

BROTORO: Dyson sphere? So do Magratheans know about Freeman Dyson?

SLARTIBARTFAST: Who? You misunderstood me. I used the Magrathean term for “spherical mega-structure that captures all radiated energy from a central power source,” and that little fish I put in your ear translated the concept into a term you are familiar with. I’ve never heard of a freemandyson.

BROTORO: Ah, so that’s what the fish was for. I thought it was a quaint Magrathean greeting or something.

SLARTIBARTFAST: You’re sitting there wearing a digital watch, and you think my people are quaint?

BROTORO: But wait... If Kerbin has no liquid iron core inside, how could it have a magnetic field?

SLARTIBARTFAST: Does Kerbin have a magnetic field?

BROTORO: Um... well, I’m not sure. The developers haven’t given us any magnetometers yet, but I just assumed it did.

SLARTIBARTFAST: And it well might. Magnetic fields are easy. We would just need to orbit a ring of charged matter around the black hole inside the force sphere. Adjusting the charge on the matter can give the client any magnetic field desired, and the inclination of the ring can offset the magnetic pole from the rotational axis if desired. Any field strength can be tailored for the client, although it’s easier for us if they want a simple dipole. Haven’t you wondered why Jool has such a weak magnetic field for a jovian planet?

BROTORO: It does?

SLARTIBARTFAST: Of course. If it didn’t, the planet would have powerful radiation belts, and any kerbal you sent in there for aerobraking would be late.


SLARTIBARTFAST: Yes. As in, “The late Jebediah Kerman.” Ah hum.

BROTORO: . . .

SLARTIBARTFAST: I don’t understand why Earthmen always stare at me blankly when I use that line.

BROTORO: I’m just wondering how you know about Jebediah Kerman.

SLARTIBARTFAST: It’s the Babelfish again. I just used the Magrathean word for “bad-ass space pilot,” and the fish did the rest in conjunction with your primitive brain.

BROTORO: Well. What about Kerbol, the sun of the system? How could something with that low of a mass possibly support thermonuclear fusion?

SLARTIBARTFAST: I’m not part of our stellar division... I work on the planets, and I specialize in doing coastlines... but there are two different ways we handle miniature stars.

BROTORO: One way involves black holes?

SLARTIBARTFAST: Both ways do. In one method, we simply make the force sphere around the black hole small enough that the density and pressure in the overlying hydrogen-rich material is sufficient to maintain thermonuclear reactions at the rate needed for the desired luminosity. The second way involves simply letting sufficient matter flow through the force sphere and into the black hole to provide the desired luminosity.

BROTORO: Which method did you use for Kerbol?

SLARTIBARTFAST: I didn’t say we made Kerbol. I was speaking hypothetically. Why don’t you just measure the neutrino flux coming out of Kerbol... then you could tell if there are fusion reactions going on inside of it.

BROTORO: Well... again... we don’t have any neutrino detectors as yet.

SLARTIBARTFAST: You really do need to take more interest in your greater environment. If you’re not paying attention to things outside your planet, terrible things could happen to it.

BROTORO: Yes, thank you. But what about Minmus?

SLARTIBARTFAST: What about it?

BROTORO: The developers tell us that it’s made of ice, but that can’t possibly be the case given its distance from the sun, can it?

SLARTIBARTFAST: Kerbin, like your own planet Earth, is located at a distance from the sun where the equilibrium temperature is below the freezing point of water. If not for their natural greenhouse effects, the oceans on both bodies would be frozen over. The temperature is even lower when you are dealing with a surface that has a very high albedo, like ice, since that reflects away most of the incoming energy.

BROTORO: Yes, yes, I know all that. But Minmus has no atmosphere. Its surface is in vacuum. And water ice would sublime directly into a gas and escape into space at the equilibrium temperature of Minmus. Minmus should be a gigantic comet!

SLARTIBARTFAST: Ah, I see. Young Hargledertfirst of our small moon department solved that problem.

BROTORO: Did he?

SLARTIBARTFAST: She. She engineered a microorganism that was active in the small moon’s water during its early warm phases. The organism excretes a clear polymer as a waste product...kind of like a resin. All of the ice on the small moon contains a small percentage of this polymer. When the ice is exposed to vacuum, the water will indeed sublime away, but the polymer is left behind and forms a barrier to further sublimation. And any future impacts or landing rocket flame scars on the surface are self-healing once the vapor clears.

BROTORO: Really? And that’s what you did for Minmus?

SLARTIBARTFAST: I was speaking hypothetically.

BROTORO: And I suppose you’ll tell me that Eve is purple because of a little food coloring.

SLARTIBARTFAST: Indeed. It takes a very small percentage of certain chemical compounds to give a planetary surface or atmosphere a desired color. You’d be surprised how many clients are upset if they don’t get just the right shade of purple or some other color in their skies. We are very good at this, and all the chemical stains and particulates are USDA approved.

BROTORO: You know about the USDA? Oh,’s the Babelfish again, isn’t it.


BROTORO: So... if you had to do it all over again, are their any changes you’d make to the Kerbol system?

SLARTIBARTFAST: Well, yes, now that you’ve asked. I think Kerbin would look much better with more fjords on the coastlines. I always try to put a lot of fjords on a planet, but the managers always say it’s too much. A lot of my work got erased. I was quite incensed about that.

BROTORO: Hypothetically speaking, you mean.

SLARTIBARTFAST: Um. Yes. Of course.

BROTORO: Well, our time is up. We really appreciate you coming here today. So long, and thanks for the fish.

SLARTIBARTFAST: No, I’m afraid I must take the Babelfish back with me.

BROTORO: Oh, please? I think it would be very useful *arrgh* Hey!

SLARTIBARTFAST: Flerti slark tilligert sibilas fer torrn. Ser fasto gerhs.

BROTORO: Yeah. Whatever.