14 DAY TRIAL // Since the 1960s, orbiters and rovers that flew to Mars have been observing geological features called rilles in a region of the planet called Hesperia Planum. Even now, researchers can't say for sure where these features originated, or how they came to be.
The best way to describe rilles is as series of narrow, sinuous channels, clustered in packs of a dozen or so at any location. What is most interesting is the fact that they can run for hundreds of kilometers, without displaying their source or destination.
Given the conspicuous lack of volcanoes in the Hesperia Planum, it's safe to say that the features are no volcanic in origin. On the other hand, there are no signs to suggest that water may have led to the formation of such features.
At this point, scientists are following two main leads – water and lava. Thus far, none of them appears to be winning, but experts are continuing to keep their options opened, Universe Today reports.