Nature

Gardening On Mars

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Assuming we did colonize Mars, could we garden there? Based on scientific data revealed by Pathfinder and other space missions, the answer turns out to be a qualified yes. Farming even a tomato plant on Mars would be the equivalent of raising a redwood grove on a raft in the Pacific: it’s theoretically possible and technically achievable — just not practical.

As we daily see new pictures of the tiny roving robot exploring our neighbor planet, NASA scientists don’t discount the possibility that a form of primitive life — perhaps plant life — may already exist on Mars. Or perhaps existed at one time and is now extinct. One of the researchers exploring this angle is Dr. Jack Farmer, who works in the exobiology branch of NASA’s Ames Research Center in Mountain View.

“It wouldn’t be like a plant you would grow in your garden,” suggests Farmer. “It would probably be a microbial organism, something tiny and single-celled and maybe photosynthetic. Farmer is an exopaleontologist, following up tantalizing leads such as the meteorite thought to be from Mars that appears to have chemical signatures indicative of life forms. “We’re going to be getting a piece of that meteorite here at Ames,” he says.

One of the reasons Pathfinder’s roving robot is looking at rocks is to see if they might be the type to hold a fossil record of ancient micro-organisms that may have once lived. Its more important role, says Farmer, is to lay the groundwork for a mineral analysis of Martian soil.

If there is life on Mars, Farmer suggests, it’s down below. Deep down, below a layer of ice that appears to cover the surface of Mars like a frozen tundra.

“If we were going to look for living organisms, we’d need to go deep below the surface, several kilometers down just to get through the ground ice,” says Dr. Jack Farmer, “It’s a job that would probably require humans, with big drilling rigs”

On the next few missions, roving robots with tiny scoops take what samples they can, and an orbiting surveyor scheduled to reach Mars this fall tunes up a thermal emission spectrometer to discover minerals below the ice. Farmer also hopes future missions will pinpoint areas where the ice is thinner, where thermal gas vents with a concentration of water vapor indicate liquid water below the surface — a likely spot where living organisms, or their ancient fossils, might be found.

With so much water ice on Mars — so much it can be easily seen by amateur astronomers in the form of polar ice caps, similar to those on Earth — it seems at first that agriculture might be possible in some distant era. While air temperatures on the red planet average minus 65 degrees (kind of like Minnesota in the wintertime) there are some spots near the equator that warm up to a balmy 63 degrees in the height of Martian summer. The air is chock full of carbon dioxide (95 percent) and nitrogen (3 percent) and there are some traces of oxygen in the atmosphere as well.

So a warm spot near the equator near a gas vent near a thinner layer of ground ice might be the best place to homestead. But Earth pioneers would still have to wear a space suit to survive, and crops would have to be grown indoors.

“”If you grew anything on Mars it would have to be in a greenhouse,” explained Farmer. “Outside, things would just explode like Arnold Schwarzenegger’s head in that movie Total Recall. The plant would blow into a million pieces.”

The problem, explained Farmer, is atmospheric pressure. Mars is a smaller planet, so its atmosphere has less than one percent of the air pressure normal to Earth. “This means, for example, that liquid water vaporizes instantly,” he points out. “If you put water in a watering can it would come boiling out into vapor before you could do anything with it.”

Since plants (and people) are full of water, the depressurized atmosphere of Mars would rupture our water-filled cells. But science, of course, has an answer.

“It’s called terraforming,” says Farmer. “You go to Mars and then create an atmosphere there, artificially, and progressively introduce elements that would recreate an earth-like environment.” While science fiction writers long dreamed this, one of Farmer’s colleagues at NASA is actually exploring the options for terraforming.

“It’s a legitimate idea,” says Farmer, “though the process would probably take hundreds of years.”