Nasa has confirmed the presence of water on Mars.
Streaks on the surface of Mars reveal the impact of flowing water as they change during the seasons.
The discovery of hydrated salts on slopes points directly to the presence of water.
Images taken over a number of years show the streaks' movement due to water.
It is the strongest indicator yet that there may be some form of life on Mars.
As Mars researcher Joe Michalski said, "On Earth, wherever we find water, we find life."
If enough liquid water exists it could theoretically be used to sustain human colonies on the planet. Water would not have to be transported from Earth but could be 'mined' on Mars.
It could consequently be possible to convert that water into oxygen and hydrogen, which would then be used to create rocket fuel in order to return back to Earth.