NASA has taken to its YouTube channel to add a new video to its collection of "We Asked a NASA Scientist" series.
In this week's episode Mars Geologist Eva Scheller answers, "is there water on Mars?", and says that in short, "yes", but it really comes down to how water is defined. Scheller goes on to explain that water has one oxygen atom and two hydrogen atoms and that the water on Mars isn't like the water on Earth and comes in the form of ice. This is a mixture of CO2 and water, and it's found at Mars' poles and on the surface.
Additionally, Scheller says that water can also be trapped within rocks and that a variety of different missions by NASA have measured the contents. The last form of water that has yet to be found on Mars is liquid water, but there are theories that it could be present. Researchers suspect that dark streaks called "Recurring Slope Lineae" spotted in some hillsides could be caused by liquid water, but there are other explanations on the table as well. So, is there water on Mars? Yes, but not like on Earth.

Recurring Slope Lineae.