A recent analysis of Martian surface soil samples shows that it contains about 2% water by weight. This is fantastic news for future colonists of the Red Planet.
According to a series of NASA papers just published in the journal Science, each cubic foot of the fine Martian soil contains about two pints of liquid water. That's about one litre's worth, or a quarter gallon. That's a ton — and that'll mean something a few decades from now when thirsty explorers start to colonize the planet.
Now to be fair, the molecules that make up this water are not freely accessible, but are instead bound to other minerals in the soil. To get the liquid water out, future colonists will have to partake in some chemistry, heating the soil to free the molecules from their dusty confines. It'll be an expensive and time-consuming process — not to mention all the equipment that'll have to be involved. But it's nothing that future robots and some nifty automation won't be able to handle.
As an important aside, it's worth noting that Mars might have as much water underground as Earth does.
The NASA papers, of which there are five, report on what the researchers have learned about the Martian surface from data gleaned by Curiosity during the first 100 days of its mission.
The dirt in question was extracted by Curiosity at a site called Rocknest in November 2012. Using its onboard instruments, namely the SAM module, Curiosity heated the soil to a temperature of 1,535 degrees Fahrenheit (835 degrees Celsius) and then identified the gases that boiled off. In addition to significant amounts of carbon dioxide, oxygen, and sulfer compounds, Curiosity measured a considerable amount of water.
Image: Rocks and sand at the Rocknest location. The image at right shows samples from Curiosity's third scoop. Credit: Science/AAAS
Moreover, the discovery also shows that water is likely distributed uniformly across the Martian surface, not just at the poles. This will contribute to a flexibility of options when deciding where to set up the first colonies.
It also means that the colonists — and subsequent supply missions — won't have to lug water across the vast expanse separating Mars from the Earth.
Unfortunately, the researchers also discovered a fair amount of perchlorate in the soil, which is toxic to people. It exists at a level of 0.5%, but that's enough to impede thyroid function. Consequently, astronauts will have to be very careful when working with Martian dirt.