The findings, published in Friday’s issue of the journal Science, came from extremely high-resolution images taken by a powerful camera called HiRISE aboard NASA’s Mars Reconnaissance Orbiter, which has been orbiting the planet since 2006.
A sequence of images from MRO shows long, brown streaks in the Martian spring and summer. In the colder seasons, these streaks disappeared, suggesting that they could be the flow of briny water.
“We haven't found any good way to explain what we’re seeing without water,” lead author Alfred McEwan of the University of Arizona said during a press briefing Thursday.
While the photos don’t prove the existence of water, they fit with evidence from other probes, such as the deep Martian canyons that only water could have carved.
Scientists say the water would be briny and salty, and have a freezing point much lower than water on Earth.
Mars is located at least 35 million miles farther from the sun than Earth.
See more photos from the probe below: