Terraforming Mars: Money No Object – Part 1
It might be that I just finished playing Red Faction: Guerilla, or possibly because I’m a little bit odd, but the idea of terraforming Mars has been coming up again and again in my thoughts recently. So, I have decided to take a look at the technical challenges that would need to be overcome to terraform the surface of Mars. I have assumed that money is no object. Quite absurd given the current financial climate, but I can dream.
Since beginning this article, I have realized that it is A HUGE TASK to calculate all the factors required. This article will deal specifically with defining the problem and heating of the atmosphere. Next week I will look at creating the atmosphere in the first place and putting everything together. I might even try to cost it, that should be fun! Enjoy!
Why Terraform In the First Place?
Why not? It’s challenging and is the next step on the road to humanity being a space faring species. If we can’t terraform another planet then a sustainable population will not be maintainable on other planets. Let’s face it, it would suck to live on another planet and not be able to walk around, breath the air and generally live our lives outside of space suits. It would be cool to live on another planet for a little while under those conditions, just for the novelty, but in the long term, I think terraforming is pretty important.
Mars: Basic Facts
I got these from Wikipedia but they could come from any basic physics textbook with a decent section on astrophysics. All units are given as fractions of Earth’s equivalent unless stated and are approximated to a reasonable accuracy.
- Mass – 0.1
- Volume – 0.15
- Surface Area – .28
- Mean Density -3.94 grams per cubic centimeter
- Surface gravity – 0.38 g (Earth = g)
- Escape Velocity – kilometers per second (Earth = 11 km/s)
- Surface Temperature – 227K (mean, expressed in absolute, Kelvin, temperature. Earth’s mean surface temperature is 287K)
- Atmosphere – 95% Carbon Dioxide, 3% Nitrogen, 1.5% Argon (approximates)
Basically Mars is smaller than Earth in every way. The atmosphere is the most important thing to consider in terraforming. Earth’s atmosphere looks something like 78% Nitrogen, 21% Oxygen (diatomic species of both) with everything else being trace elements.
The escape velocity is the key parameter here. This is dependent on the surface gravity and therefore the mass of the planet.
Method
Great idea, lets terraform a planet. We know a little bit about Mars so how are we going to go about changing the currently cold surface and unbreathable atmosphere into a temperate environment with an atmosphere suitable for humans to breath?
We will warm the surface using orbiting mirrors in a geostationary orbit. They will capture solar energy and reflect it onto the surface. They will not be focused at a point like at this solar power-station but diffuse the energy across a wider area. More on this later.
To change the atmosphere is more difficult conceptually (and from an engineering standpoint too!). We will do this in two stages. The first will be a massive dump of chemicals into the atmosphere to get them to the levels we want and the second will be a steady state where we introduce the same amount of chemicals being lost. Ideally the second stage would be self sustaining. I will investigate this later.
Heating The Surface
I mentioned previously that we would capture the sun’s energy using interplanetary mirrors which reflect the energy back onto the surface of Mars, thus heating it up. Ideally we want a temperature similar to that of Earth. Mars is about 1.5 times the distance of Earth from the sun (this changes depending on the time in it’s orbit, between 1.3 and 1.6 times) and has a radius 0.5 times the Earth’s radius. At equal distances from the sun that would mean Mars has 1/4 the collecting area of Earth. Energy density is proportional to the reciprocal of distance squared (1/r^2 law, there is no mathematical formatting), doing a bit of quick maths I make out that Mars has 10% of the energy capturing potential of Earth.
The specific heat capacity of air (how much energy it takes to raise a given amount of air 1 degree) is about 1 kJ per kilo, per degree. Assuming we can get an atmosphere on Mars, we would need to warm it up during the day by about 60 degrees. How much air would we need to make up this atmosphere? I will define space as being the Karman line, 100km above the Earth’s surface. Approximately 1/63 of Earth’s radius. Scaling with Mars’ radius, this would be about 53km. I very crudely calculate this to be about 3000,000,000,000,000,000 kg of atmosphere. This means that we need that 1ZJ (Z is a zetta, 1 billion terra, Joules) of energy to raise the atmosphere’s temperature by 1 degree, or 60 ZJ to get it to where we want it.
I haven’t included my whole calculation here but I am happy to take a picture of my back of the envelope (literally) calculation. I don’t want to solve the barometric formula for Mars here but if someone else wants to, they can be my guest. Let me know the results and I will update accordingly. Right now my 1/3 approximation will do.
We will take a timescale of 100 years (3000000000 or 3 Giga-seconds) meaning we need 20 Peta-Watts of power to be harnessed. Luckily for us, the sun’s Luminosity is over 100 Yotta-Watts but it is a long way away. If you are struggling with the prefixes, don’t worry. I had to look them all up too! The solar coefficient is approximately 1400 Watts per square meter at Earth which translates to about 620 at Mars’ distance from the sun using the inverse square law. To get our 20 petawatt we would need 31 million kilometer squared arrays of mirrors to collect enough power from the sun to heat the planet.
Phew!!!!
Coming Next Week
Next week I will write about creating the atmosphere. The mathematics is a bit more involved and I want my trusty scientific calculator to hand before I start. The calculator on my mac just doesn’t cut the mustard for this.
If you see a mistake in my calculations, feel free to contact me using the contact form or post a comment. I’m pretty sure the maths is all correct. The science, I’m not so sure about. This is a ZERO’th order approximation and should be treated as such.
Of course, one good method of warming planets which we have direct experience of is the use of greenhouse gases. With much fewer mirrors aimed at the poles one could evaporate the frozen CO2 and trigger global warming, which would not only heat the planet but raise its equilibrium temperature and reduce the radiation into space which would otherwise lose you most of your added heat.
I use this plugin for LaTeX. It’s a bit basic in some respects but fine for the odd formula.
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Everything dynamic and very positively!