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Weather on ancient Mars: Warm with occasional rain, turning cold

Christian Fernsby |
A new study of conditions on Mars indicates that the climate 3 to 4 billion years ago was warm enough to provoke substantial rainstorms and flowing water, followed by a longer cold period where the water froze.

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Topics: MARS    WEATHER    RAIN   

This may have implications on the conditions for the development of life on Mars Scientists have long known that water was abundant on ancient Mars, but there has been no consensus on whether liquid water was common, or whether it was largely frozen in ice.

Was the temperature high enough to allow the water to flow? Did this happen over an extended period, or just occasionally? Was the surface a desert or frozen? Warm conditions make it much more likely that life would have developed independently on the surface of ancient Mars.

Now a new comparison of patterns of mineral deposition on the red planet with similar depositions on Earth lends weight to the idea that early Mars had one or more long periods dominated by rainstorms and flowing water, with the water later freezing.

Presenting the findings at the Goldschmidt Geochemistry Conference in Barcelona, Professor Briony Horgan (Purdue University) said, “We know there were periods when the surface of Mars was frozen; we know there were periods when water flowed freely. But we don’t know exactly when these periods were, and how long they lasted.

“We have never sent unmanned missions to areas of Mars which can show us these earliest rocks, so we need to use Earth-bound science to understand the geochemistry of what may have happened there.

“Our study of weathering in radically different climate conditions such as the Oregon Cascades, Hawaii, Iceland, and other places on Earth, can show us how climate affects pattern of mineral deposition, like we see on Mars.

“Here on Earth, we find silica deposition in glaciers which are characteristic of melting water.

“On Mars, we can identify similar silica deposits in younger areas, but we can also see older areas which are similar to deep soils from warm climates on Earth.

“This leads us to believe that on Mars 3 to 4 billion years ago, we had a general slow trend from warm to cold, with periods of thawing and freezing.

“If this is so, it is important in the search for possible life on Mars.

“We know that the building blocks of life on Earth developed very soon after the Earth’s formation, and that flowing water is essential for life’s development.

“So evidence that we had early, flowing water on Mars, will increase the chances that simple life may have developed at around the same time as it did on Earth.


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