Green Mars

Felonyboy writes "A New Zealand scientist has grown asparagus and potatoes for the first time in soil taken from Martian meteors. Click here for the full story."

Comments

This experiment ignores the big problems.

[Christopher Thomas]

While interesting for a sound-bite, this experiment doesn't prove a whole lot about growing plants on Mars.

Soil is pretty much inert. It's there to keep the plant from falling over. If you're lucky, you'll get soil with good water retention/drainage capabilities. However, this isn't exactly hard to come by or hard to produce yourself. While at any given time, soil will have nutrients and so forth in it, these cycle through fairly quickly - you have to keep adding them back, by using natural or artificial fertilizer.

The main problems with growing plants on Mars are, in order:

• Lack of water.
  
  No water, no plants. Water provides hydrogen for hydrocarbon synthesis. We simply don't know whether there's much water present on Mars. There are trace amounts in the atmosphere and ice caps, but we'll need more than trace amounts for agriculture. There may or may not be ice deposits beneath the planet's surface.
  
  
• Air Pressure.
  
  Anything growing on Mars would have to be in a pressurized greenhouse. The air is far too thin to support life otherwise (low throughput by weight and very low boiling point of water at Martian densities (if liquid water can exist at all)).
  
  
• Mostly-CO2 atmosphere
  
  Most plants do not grow in an atmosphere of pure CO2. You'd have to fiddle with the atmosphere composition inside your pressurized greenhouse, which will take a fair bit of startup effort (it may be self-sustaining once plants are growing).
  
  
• Lack of nitrogen, phosphorus, and potassium.
  
  These are the primary nutrients supplied by fertilizer. You're going to have to make sure that there are minerals bearing all of these within easy reach of any large-scale agriculture, and you're going to have to have the industry to process them into fertilizer. Appropriate minerals may or may not show up on orbital surveys (depends on the geology). I have no idea how common these minerals are. Common or not, industry is expensive.
  
  
• Lack of sunlight.
  
  Mars is (very roughly) twice as far from the sun as the Earth. It gets one quarter as much sunlight. While some plants will grow under these conditions, they won't grow as well as they would on Earth.
  
  
• Unshielded sunlight.
  
  Our atmosphere screens out a lot of the UV and other nastiness produced by the sun. The martian atmosphere won't (it's far too thin). Ionizing radiation (UV and other) will damage the plants' health more rapidly than on Earth.
  
  

While these issues are all tractable, none of them are addressed by the article. Thus, I have trouble taking the article seriously.

Now wait a damn minute!

[tesserae]

At the moment pieces of one of those martian meteorites, Dar al Gani 476, are being commercially sold for around $300 a gram (search for "DaG476" in the page)...

I'm a farm boy; I can assure you that asparagus and potato plants aren't exactly tiny. If this guy grew asparagus and potatoes in this soil, he either had a huge budget or he didn't grow the plants very large. Matter of fact, the meteorites themselves almost certainly didn't weigh more than a few pounds each -- most of 'em are pretty small. And I doubt that the owners would allow someone to use the whole thing up for a couple of plants, and even if he did he wouldn't grow either crop to maturity in a pound or two of soil!

My guess is that he grew only sprouts and compared a few days growth, using a few grams of material. The only other way to manage it would be to use the samples to prepare a larger quantity of chemically-similar soil, and grow the test plants in that, but the story doesn't indicate that at all. Too bad there isn't a link to the research paper.

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