26 June 2008Rachel Courtland
Some Martian dirt has the same basic chemistry as garden soil, a new analysis from the Phoenix lander suggests. The find widens the range of organisms that might be able to live on Mars.
Although the analysis is not yet complete, the lander has already found trace levels of nutrients like magnesium, sodium, potassium and chloride. Although these ingredients were known to exist in Martian soil, until now no one was sure whether they would be soluble in water and thus potentially available for life.
The encouraging result came from a test of soil excavated from the top few centimetres of a region called Wonderland at the lander's site in the northern plains of Mars. The sample was delivered on Wednesday to the lander's wet chemistry laboratory in the Microscopy, Electrochemistry and Conductivity Analyzer (MECA) instrument.
In addition to detecting soluble nutrients, MECA also found the sample to be fairly alkaline, with a pH of 8 or 9. This level of alkalinity is common for many Earth soils, and myriad bacteria and plants, including vegetables like asparagus and turnips, can thrive at such a pH. On Earth, exotic microbes have been found in water with bleach-like pH levels greater than 12.
"It performed flawlessly yesterday, and we were all very flabbergasted at the data we got back," said MECA wet chemistry lead Samuel Kounaves from Tufts University in Medford, Massachusetts, US.
Friendly to life
If the soil conditions are relatively mild, "this means that there's a broader range of organisms that can grow in this soil", says Kounaves. "There is nothing about it that would preclude life. In fact it seems very friendly."
Recent studies have suggested that Mars might be too acidic or too salty to support life.
While this particular beakerful of Martian soil may be just right, the sample may not be representative of conditions farther below the surface, team members said. Digging down deeper could unveil saltier soil or soil with a different pH.
MECA has three compartments left for wet chemistry experiments. Although the team has not yet decided how to use them, they may dig down deeper to sample layers in the same patch of ground, including a layer close to or including ice.
The instrument will also look for other key nutrients like nitrogen, but those results may take several more days, says Kounaves.
Mars – The Red Planet is full of surprises; learn more in our continually updated special report
