Volume: 01, Issue: 11 08/27/2003 
Photo of rocks on Mars from NASA's Viking 2 lander.
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A chamber containing two phases of carbon dioxide--liquid and gas. As temperature and pressure increase (from left to right), the two phases merge to become a supercritical fluid.
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Other Articles in This Issue:
Help Choose Mars Photography Sites
NASA Satellites Eye Forest Fires
The First European Lunar Probe to be Launched
 

Scavenging the Red Planet

Mars itself may not be the first place astronauts would look to gather supplies while exploring the Red Planet, but chemical engineer Ken Debelak of Vanderbilt University is trying to change that opinion.

"We might have to do what explorers have done for ages: live off the land," Debelak said.

When undertaking the long journey to Mars, astronauts will not be able to carry with them everything necessary for survival. Crews could possibly be away from Earth for a few years. Due to limited cargo space aboard the shuttle, astronauts would have to make do with what can be found on the planet.

Debelak is currently involved in a NASA project examining this idea of reaping the resources available on Mars. The saving grace of the otherwise desolate planet, according to Debelak, is the carbon dioxide (CO2) comprising the Martian atmosphere.

The planet’s atmosphere is nearly entirely composed of CO2. Debelak said this CO2 can be used to reap a wealth of other elements hidden inside Mars’ soil and rocks, including oxygen, water, and magnesium and hydrogen to be used for rocket fuel.

"When CO2 is compressed to a pressure of 73 atm and heated to 31.1 degrees Celsius, it becomes a supercritical fluid--and a marvelous solvent," Debelak said.

By manipulating temperature and pressure, substances can become supercritical, meaning they are heavy like liquid but with able to penetrate like gas. Using supercritical CO2 makes for an extremely effective solvent to use to extract these other elements. Although this process is not employed much on Earth, Debelak says it will be crucial to the astronauts exploring Mars.

Water is the most notable asset that can be reaped from supercritical CO2. Martian rocks often contain hydrogen, and when supercritical CO2 seeps into the rocks and the carbon takes hold, the remaining oxygen bonds with the hydrogen to create water.

The available water will have several uses. According to Debelak, water can be used not only for drinking, but also, "you can split water into hydrogen for fuel, and oxygen for breathing--or as an oxidizer for some sort of engine."

Debelak is also currently exploring the merits of using magnesium from Martian soil that’s been dissolved by supercritical CO2. Magnesium is highly flammable, making it an excellent choice for rocket fuel. Debelak also has determined another use for magnesium: it could be used to construct a lander. When the mission was finished, said Debelak, “You could chop it up, pack it into a rocket engine, and then add some other oxidizer to fire it off."

There could be other elements that could prove valuable if put together with supercritical CO2. Debelak is currently researching reactions of supercritical CO2 with a wide array of substances. But his work is not easy, as CO2 serves a different purpose on Mars than Earth. "Mars is a totally foreign environment to us. The rules are different," Debelak said. "So that's what we're doing--trying to figure out the rules. And then we can figure out how to play the game ... on both planets."

    
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