The surface of Mars is barren and inhospitable, but perhaps it hasn’t always been this way. Billions of years ago, the climate on Mars was very similar to that of Earth, according to a new NASA-funded study. Here’s the evidence
That Mars is an arid and inhospitable planet is clear to everyone. Things, however, have not always been this way and, indeed, in Mars’ past there would be a climate very similar to that of Earth. A new NASA simulation reveals that three billion years ago the Martian climate was very similar to that of today’s Earth, with oceans and glaciers. Scientists also believe that the period when Mars it could have hosted life is longer than previously expected.
How the inhospitable planet we see today became
The late Noachian period (4.1 to 3.5 billion years ago) is the period thought to be habitable on Mars, with rainfall near the equator, as demonstrated by water-eroded valleys found on the red planet’s surface. However, over the years Mars gradually arrived at its current climate, with an atmosphere too cold and thin to support liquid water, a necessary ingredient for the evolution of life. Scientists are trying to figure out how long this period of habitability would last.
Understanding the climate in Mars’ past is not easy, given that the characteristics of the surface do not seem to support either a hot and humid or a cold and dry climate. A hot and humid climate, for example, would have produced large erosions of running water: the problem is that there are few valleys of this type, which date back to that period. On the other hand a climate that is too cold it would freeze any ocean most of the time. It is true that a moderate cold climate would have allowed water to pass from the ocean to the land in the form of snow and ice, but this would also have prevented the formation of tsunamis, which, somewhat surprisingly, occurred on Mars .
New NASA simulations show that Mars’ climate may have been cold and wet in its past. Scientists believe it would have formed an ocean in the northern part of the planet, which would have remained liquid despite the cold outside temperatures. In addition, the atmosphere of Mars is mainly composed of carbon dioxide. If it had been denser in the past, it would have trapped heat, allowing water to remain in a liquid state on the planet’s surface.
The ancient climate
The ancient climate of Mars was simulated using NASA’s GCM. The engineers pieced together the actual Martian landscape with the hills, craters and all; then they removed all the current ice sheets and inserted a small northern ocean, setting the boundaries indicated by current geologic evidence. A future space mission called Mars Ice Mapper will be able to study the structure of the Martian subsurface to look for evidence of this ancient ocean.
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