The water is not present as a liquid, however, but as molecules attached to other minerals in Martian soil. If the soil is heated to 835 °C, the water molecules can be easily extracted. In every cubic foot of Martian dust, it is estimated there will be about 2 pints of liquid water.
This discovery would make it easier to include astronauts on future missions to Mars, according to Laurie Leshin, dean of science at the Rensselaer Polytechnic Institute. She says that "When we send people, they could scoop up the soil anywhere on the surface, heat it just a bit, and obtain water."
Despite Mars' image as a dry planet, experts have long believed that water would be found on the planet, due to the formations on the planet's surface. Along with news of the discovery of water molecules, it has also been announced that pebbles "formed by running water" have been identified. These findings, published by NASA scientists in the journal Science, were included in five papers on the work carried out by Curiosity over its first 100 days on Mars.
However, another discovery has complicated plans for building colonies on Mars. A chemical called perchlorate, which is toxic to humans, was also picked up in the Martian dust. This substance now appears to be quite widespread, and may explain why no organic material has yet been discovered.
Lead Curiosity scientist John Grotzinger, with the California Institute of Technology, said as perchlorate breaks down when heated, it may be degrading organic material in tested samples. "We as a community will have to wrestle with understanding the behavior of perchlorate," he said.
Curiosity landed in the Gale crater on Mars on Aug 6, 2012. These papers from NASA only cover the first 100 days of Curiosity’s mission, when the team concentrated on testing its instruments, so many more exciting discoveries may lie ahead.
As Leshin told the Guardian: "I do think it's inevitable that we'll send people there and so let's do its as smartly as we can. Let's get as smart as we can before we go."