In a recent project, I simulated Mars to see if I could get a fern to grow. A bit like a terrarium but with Mars instead of ‘Terra’ inside, a ‘marsarium’ if you will. Yeah Pauly Shore, you better be proud. I made a baby biodome.

Marsarium 9, with the fern Lt. Ellen Ripley inside.

It created a little problem though. How am I going to get some Mars dirt down here in little old Queensland? I’m no Internet Billionaire. So starting a rocket company, flying a robot to Mars and collecting samples wasn’t an option.

Soil samples from the side of the Pu’u Nene Volcano in Hawaii are apparently a pretty close ‘spectral analog’ of Mars. But importing dirt from Hawaii into Australia? That sounds like a quarantine nightmare. I needed a way to mix up a batch of Mars dirt on the cheap, from local ingredients. First, I needed the recipe.

All those amazing rovers that NASA’s Jet Propulsion Laboratory send to Mars? Like Curiosity that they ‘sky craned’ down to the surface of Mars? They have instruments for analysing the soil composition of Mars. Sure rovers and rockets and all that hardware are rad. But you know what makes NASA really cool? How they share what they learn. Like their Mars soil analysis! The results look like this:

NASA graph of elemental composition of Mars soil.

The five most abundant ingredients, account for almost 90% of the dirt taken from Mars samples.

  • SiO2 - 49.5%
  • Fe2O3 - 17.9%
  • Al2O3 - 7.2%
  • MgO - 7.7%
  • CaO - 6.7%

That seems like a good starting point. If I pad those out to reach 100% and use the results as a weight ratio, it should make a decent first batch of home-made Martian soil. Luckily most of this stuff can be found in hardware and health food stores.

SiO2

Silicon dioxide, yeah sand. You can go budget and get a bag of propagation sand (it won’t be 100% silica). If you want a bit more precision you can hunt around for educational or scientific samples that contain less impurities. You can get 2.7 kilograms for about $16

Fe2O3

Iron oxide, is red cement colouring and is often advertised as red oxide or similar. You can get 2.2 kilograms for about $20

Al2O3

Aluminium oxide, is used as an abrasive. It gets stuck to sandpaper and is used in sandblasting. It was a bit difficult obtaining smaller amounts in Australia (places wanted to sell me 20kg bags). You can get 340 grams for about $10.

MgO

Magnesium oxide, is a dietary supplement found in health food stores. You can get 225 grams for about $10.

CaO

Calcium oxide, Now this one is tricky. I couldn’t easily buy calcium oxide. It seems that calcium oxide reacts with CO2 in the air and gets converted into calcium carbonate. But you can buy calcium carbonate (CaCO3) as a dietary supplement. This can then be turned into calcium oxide by ‘lime-burning’, just heat it up in a kiln to above 825°C. You can get 340 grams of calcium carbonate for about $10

I don’t have access to a Kiln, so I left it as calcium carbonate. I figured as soon as the calcium oxide cooled, it wouldn’t last long and end up back as a carbonate anyway.

But this raised an interesting question. Why is the calcium oxide on Mars stable? The martian atmosphere is mostly CO2, so why doesn’t it combine with the calcium oxide to form a carbonate?

So yo, NASA if you are reading this: With all that CO2, why is there calcium oxide on Mars and not calcium carbonate?

Air-tight container filled with simulant mars dirt. Labelled do not eat, mars dirt.

Method

Wear protective equipment to cover your nose and mouth before combining the materials.

Using digital scales, measure out the following amounts:

  • SiO2 - 54.5% (329g)
  • Fe2O3 - 20.9% (127g)
  • Al2O3 - 8.2% (50g)
  • MgO - 8.7% (53g)
  • CaCO3 - 7.7% (47g)

Combine well.