As the Telegraph reported, the dark marks, which appear in summer months, are thought to be caused by the salty water wicking up from a shallow flow beneath the surface - although the origins of the briny flows remain a mystery.
At a news conference this morning, scientists announced that Mars isn't the dry, arid planet they once thought and that it does have a water cycle, although they don't know where the water comes from.
"Our quest on Mars has been to 'follow the water, ' in our search for life in the universe, and now we have convincing science that validates what we've long suspected", said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. Scientists (and humans) have always wondered about life existing beyond earth and the hopes and means to travel there, so this announcement is nothing short of a potential breakthrough.
This discovery raises the chances of Mars being home to a few form of life.
But he called the apparent confirmation of liquid water "encouraging" and "quite exciting" for those who seek life on the next planet farther from the Sunday.
Earlier that same year, the team behind the Opportunity rover found evidence that the planet had once had non-acidic water, the kind "you can drink".
Photos from NASA's Mars Reconnaissance Orbiter show dark streaks flowing down Martian slopes. The water's salt content is important because without it the water would freeze in Mars' exceptionally cold climate. And Google didn't miss the opportunity to celebrate the landmark discovery via an innovative Doodle, which depicts the round Red Planet sipping a glass of water.
"They may be thinking now about alternative targets for research and what part of Mars they might want to think about landing in", Alexander says. The researchers propose that the salts detected would lower the freezing point of water, just as salt facilitates ice melting on roads here on Earth.