Documentation for KEPLER Copyright (c) 1988, Don Sakers 72517,526 WHAT IS KEPLER? KEPLER is a program written with the science fiction writer in mind. It generates habitable planets and their planetary systems. HOW DO I USE IT? The prompts are pretty self-explanatory. In the usual mode, KEPLER randomly generates specific values for a star and then a habitable planet. You are given the opportunity to accept those values as generated, or to substitute values of your own. NOTE: Many values are interrelated. A planet's year, for example, depends on the mass of the star and the distance of the planet. Thus, you can change mass and distance but _not_ the length of the year. Following are specific prompts [in brackets] and comments regarding your responses. [Hit any key to begin] Hit any key [Please name the planet] Give it any name you want in ASCII (alpha- numeric) characters [1- Kepler Chooses a Star 2- You Specify a Star] Under option 1, you give the star's spectral class, KEPLER creates values to fit. Under option 2, you give KEPLER values (i.e. for a particular pre-existing or pre-created star (This is useful if [a] you want to create a planet for Alpha Centauri, Canopus, Betelguese, etc. or [b] if you have an already-created star and you want KEPLER to generate the planetary system.) Suppose you pick #1: [Choose the Star's Spectral Class B A F G K M] Choose one from these alternatives. B stars are hotter and bluer, M stars are cooler and redder. The Sun is a G star. (Most habitable worlds will probably be around F,G or K stars. The extremes are included so that you can have some exceptional planets if you wish. There is another spectral class ("O") beyond B, but it is very unlikely that any O stars even h^Ba^Bv^Be^B planets.) [1- Kepler generates a habitable planet 2- You specify a pre-created planet] Under option 1, KEPLER will randomly assign values. Under option 2, you can give the values for a pre- existing or pre-created planet (i.e. if you have a planet and you want KEPLER to design a planetary system) Assume you choose #1: [stellar mass xxx stellar luminosity xxx planetary irradiation xxx Does this look right (y or n)?] This is your first chance to accept or reject a value. Planetary irradiation means the amount of energy the planet gets from its sun. Earth is 1. Higher values will be warmer, lower values colder. Choose y if the given value suits your purposes, n to specify your own value. [Distance from star: xxx Does that look right (y or n)?] The given distance represents the correct figure for the given irradiation. Usually you will choose y in this case. Choosing n allows you to change the distance...which will change the irradiation. [Period of revolution xxx Shall we continue?] Revolution is determined by the distance and the stellar mass. You get no choice on this one. KEPLER is just trying to be polite. [Do you want to pick the surface gravity? (y or n)] y=you specify a particular figure for surface gravity n= KEPLER makes random choice based on diameter and density. [Diameter xxx Does this look right?] Answer y if the planet is the size you want. Answering n allows you to specify a particular size. [Density xxx Mass xxx Surface gravity xxx Does the gravity look right (y or n)? ] Mass and density depend on surface gravity. Answer n to choose your own value. It i^Bs^B possible to get yourself in a bind here, since mass, density and surface gravity are all interrelated. If you try to change too many values, KEPLER will tell you "I think we should start over." Usually, you will just want to accept the values given and work with them. If you _must_ specify your own values, stick to o^Bn^Be^B of gravity, diameter and density. [Input length of day (hours)?] You're on your own with this one. Choose whatever you want. [Local year is xxx local days.] [Printing into PLANET.DO] Your work is over. KEPLER will now print the values for your planet into a textfile called PLANET.DO. Suppose you choose #2 above: [You Specify a Star:] KEPLER will print a table of Class, Mass and Luminosity and then ask: [Stellar Mass (Sol = 1)?] Enter a value. If you have values for a particular star, (which you might find in an astronomy book) fine. If not, ranges are given in the table. [Stellar luminosity (Sol = 1)] ditto You will then wind up at: [1- Kepler generates a habitable planet 2- You specify a pre-created planet] Suppose you choose #2: [You Specify a pre-created planet] You will be asked: [What irradiation?] Enter a value (Earth = 1) [Distance from star (million kilometers)?] Enter a value (Earth = 149.6) [Diameter (Earth = 1)] Enter a value [Density (g/cc)[Earth=5.5]] Enter a value [Mass is xxx times Earth. Surface gravity?] Enter a value [Input length of day (hours)?] You're on your own In whatever case, you will eventually get to: [Local year is xxx local days. Printing into PLANET.DO] [Shall we do the rest of the system (y or n)?] n means KEPLER will start over from the beginning. y means KEPLER will create a planetary system of 4-12 planets, including your world. Planets will be of four types: Methane giant (like Uranus & ^LNeptune ), Jovian (like Jupiter & Saturn), Asteroids (like...uh...the Asteroids) or Rocky (_not_ the Flying Squirrel). Rocky planets may also be Habitable or Venus- type. Values given are: Type, distance from star, mass, period of revolution, diameter, density, surface gravity, rotation and irradiation. (In the case of Asteroids, most of these values don't apply and have been set to an arbitrary .0001) PROGRAM ASSUMPTIONS: 1. Planetary distances follow a Titius-Bode relationship. 2. Asteroids are always next orbit in from a supermassive Jovian. OTHER CONSIDERATIONS: Jovians, Methane Giants, Venus-types and Habitables form depending upon the irradiation at that distance. If a Rocky planet is at the right distance, it has a chance of being either Habitable or Venus-type. Rocky planets may form at any distance. Conditions for habitability: Irradiation of 0.3-2.0 Gravity less than 2 gees You will see: [Calculating... Printing planet 1 into PLANET.DO Printing planet 2 into PLANET.DO etc.] After the system prints, KEPLER will say: [That was fun. Want to do another (y or n)?] y = restart program n = stop DISCLAIMERS: I am not a physicist, astronomer or programmer. This program works to the best of my knowledge. However, I do not guarantee that the program or the underlying mathematics are complete or correct. USE AT YOUR OWN RISK. KEPLER is intended to give values that are illustrative rather than rigorous (i.e. this is a _cold_, _massive_ planet with a _high_ surface gravity. ) I am not responsible for any errors in figures used her...if you intend to use actual numbers from the program, please verify them or have a techie friend do it for you.