A new study suggests that the presence of hydrogen in Mars may have allowed liquid water to flow. They presented evidence of surface trails in the Nanedi Valles which seem to once have waters flowing on it about 3.8 billion years ago.

Researchers from the Penn State University led by Ramses R. Ramirez believe that hydrogen combined with carbon dioxide resulted to greenhouse effect which elevated the temperatures of the Red Planet. It was warm enough allowing water to flow.

In order to prove their theory, they created climate models combining the two elements. They presented a probable Martian atmosphere that has abundant carbon dioxide, water, and hydrogen. They showed how the planet froze and melted thus allowing water to flow 3.8 billion years ago.

"This is exciting because explaining how early Mars could have been warm and wet enough to form the ancient valleys had scientists scratching their heads for the past 30 years," said Ramirez in a press release. "We think we may have a credible solution to this great mystery."

Another theory they have was the possibility of a meteorite hitting the planet and making the temperature warm to allow steam to evaporate causing rainfall. However, they had to eliminate that as a possible explanation as rainfall will not be that significant to create the depth of and length of Nanedi Valles which is 4 km wide.

"We think that there is no way to form the ancient valleys with any of the alternate cold early Mars models," said Ramirez. "However, the problem with selling a warm early Mars is that nobody had been able to put forth a feasible mechanism in the past three decades. So, we hope that our results will get people to reconsider their positions."

So where did the hydrogen come from? Their theory suggests that it may be emitted by the planet’s active volcanoes.

The study was published in the Nov. 24 issue of  Nature Geoscience.