Dear friends!
I discovered Universe Sandbox last week and I realized this is a great tool I always wanted . Two days later, I found out there is US2 Alpha available, so I immediately bought it and it seem super-cool! It is (or as I hope soon will be) an ultimate tool for creation of fictional solar systems. I am a physicist and although astronomy or astrobiology are not my field, they are certainly my big hobby. I really appreciate the scientific approach you are taking towards modelling of planetary climates. I am sending a few ideas you might find handy.
Bug I noticed in Alpha 10.0: When I change planetary temperature in degrees of Celsius, the temperature gets severely broken or ends up at -273 C. Kelvins work fine.
CO2 and water into atmosphere: Apart from the great climate modeling system, that so far seems to work only for Earth (are there plans to extend it to all planets?), I noticed that there are two independent systems. One lets you specify the mass and other parameters of the atmosphere and from this, the greenhouse temperature is calculated. (Is there any reference to how is this done? The predictions seem reasonable, so I am quite curious.) Independently of this, one can specify amount of water and CO2 in the planetary composition. It seems to me that these systems could be quite easily coupled to obtain very realistic climate model:
a) If water is present in the composition part, according to planetary temperature some part gets vaporized. From amount of this vapor, water greenhouse effect can be calculated and this can be added to the overall greenhouse effect.
b) If CO2 is present in the compostion part, according to planetary temperature some part gets vaporized. From amount of this vapor, water greenhouse effect can be calculated and this can be added to the overall greenhouse effect.
So at the end, we could have these parameters for atmosphere composition:
- Inert atmosphere mass (N2, Ar and similar non-freezing inert compounds) - this would replace the atmosphere mass parameter
- Water mass (in planetary composition)
- CO2 mass (in planetary composition)
Then we could calculate total atmospheric greenhouse effect, pressure and other thing from temperature and these three parameters. Like this, one could, for example bring Mars slightly closer to the Sun and observe how the frozen CO2 defreezes and how Mars gets terraformed. Or one could observe the atmospheric collapse as the CO2 in the atmosphere freezes. Or the wet greenhouse effect for planets with water. (I am not sure if now one can get the transition into a snowball for a general planet, without the climate model. With this simple dependencies of greenhouse on three parameters, you could.)
Molecular mass that gets retained by the planet: I am really missing this parameter, which was present in Sandbox Universe 1. (Or have I just overlooked it?) I am always looking at this number when I am thinking how thick atmosphere can I give to a particular planet. Could you please bring it back?
Show orbital reconances: I noticed there is many very useful and cool features from orbital mechanics in the Universe Sandbox. Lagrange points, Hill sphere, Roche limit, etc. Just an additional idea: it would be very interesting to show
orbital resonances of bigger bodies. In the timescale of millions and billions of years, the resonances either stabilize planet's trajectory, or completely destabilizes it. Similarly to lagrange points, they are definitely interesting feature to show.
Include tidal-locking half-time into default rotation rate calculation: This is another feature that could, in my opinion, enhance the simulation of US. (I have written similar thing for the
Pioneer Space Simulator (link points to the relevant code)). The idea is, that during millions of years of the solar systems existence, planets tend to tidal-lock. The half-time of this process is approximately given by formula
time ~ semiMajorAxis^6 * radius / planetMass / parentMass^2 (times some properly chosen constant).
Currently, user can chose to tidal-lock a planet in the Sandbox Universe, but it would be very helpful, if the user would just chose the age of the parent body and the newly generated planet would automaticaly have its rotation period adjusted towards the tidal-lock according to distance from the parent body, time, mass of both the planet and the parent body, etc.
Simple way how to do it is, for example to chose some initial rotation period and orbital parameters for the planet. One would then calculate how would this trajectory change upon tidal locking (zero eccentricity, axis perpendicular to the plane of rotation, same angular momentum as the initial trajectory). According to age, one would then calculate the default trajectory as:
default trajectory = original trajectory * lambda + tidal-locked trajectory * (1-lambda),
where lambda = 1 for zero time passed, lambda = 0 for time when planet is completely tidally locked.
These are only ideas, of course, maybe you will find some of them helpful. I also had some ideas how you could obtain energy transfer from equator to pole or how you could obtain distribution of deserts depending on planetary rotation from some simple formulas (Hadley cell model), but I will write these later. Anyway, thank you for your great work! Universe Sandbox is really nice and I really like it a lot!
Topic: Few ideas (Read 2598 times)
