16:31 29 September 2015
NASA has obtained images showing evidence of running waters on Mars, which could suggest alien life forms have lived on the planet.
Satellite images showed narrow streaks that appear on slopes during warm seasons and fade when conditions become cooler.
NASA wrote: "Water is essential to life as we know it. The presence of liquid water on Mars today has astrobiological, geologic and hydrologic implications and may affect future human exploration."
Meanwhile, Lujendra Ojha, the lead scientist, added: "Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars."
Dr Joe Michalski, a Mars expert at London's Natural History Museum London, said: "These results provide strong evidence that salty water occasionally flows on the Martian surface, even today.
"We know from the study of extremophiles on Earth that life can not only survive, but thrive in conditions that are hyperarid, very saline or otherwise 'extreme' in comparison to what is habitable to a human. In fact, on Earth, wherever we find water, we find life.
"This finding is yet another example of water on Mars, but a hugely important one because it points to environments that could potentially be habitable to certain kinds of bacteria, even today."