Research carried out by a collaborative team from Imperial Collage London
and University Collage london suggests that during a period approximately
3 million years ago know as the Hesperian Epoch, Mars had lakes formed of
melted ice. Each lake, around 20km wide are situated along parts of the
equator.
Previous research had suggested that there was a possibility that Mars was
once warm and wet early in its history, but it was believed that between 3.8 – 4
Billion years ago it became cold and dry and unable to sustain liquid water.
The new study carried out using images from NASA’s MRO ( Mars
Reconnaissance Orbiter ) which is currently in orbit of Mars, concluded that
there were periods of a wetter warmer climate more recently the previously
believed.
Researchers on the study believe there may have been an increase in volcanic
activity, a shift in Mars`s orbit or Meteorite impacts, any of which could have
warmed the atmosphere sufficiently enough to melt the ice. The result from this
would have created gasses which thickened the atmosphere temporarily
trapping more sunlight and keeping things warm enough to sustain liquid
water.
Lead author of the study, Dr Nicholas Warner, from the Department of Earth
Science and Engineering at Imperial College London, says:
“Most of the research on Mars has focused on its early history and the recent
past. Scientists had largely overlooked the Hesperian Epoch as it was thought
that Mars was then a frozen wasteland. Excitingly, our study now shows that
this middle period in Mars’ history was much more dynamic than we previously
thought.”
Researchers used the images from NASA to analyse flat floored depressions
located above Ares Vallis, a Giant Gorge 2000km in length which runs arcoss
the equator of Mars.
Scientists had previously believed that the depressions were created by
Sublimation, a process where ice changes directly from its solid state to gas
bypassing the liquid stage.
During this new study, researches have found a network of channels running
from depression to depression which could only be formed by running water.
Scientists backed up this theory by making comparisons to images of
Thermokarst Landscapes which are found on earth today in places such as
Alaska. Thermokarst Landscapes are areas where the permafrost is melting
creating lakes and channels.
Professor Jan-Peter Muller, Mullard Space Science Laboratory, Department of
Space Climate Physics at University College London, was responsible for
mapping the 3D shape of the surface of Mars. He adds:
“We can now model the 3D shape of Mars’ surface down to sub-metre
resolution, at least as good as any commercial satellite orbiting the Earth. This
allows us to test our hypotheses in a much more rigorous manner than ever
before.”
This research is believed to be of future benefit to teams of astrobiologists
looking for evidence of life on Mars as the areas indicated would have possibly
been suitable for microbial life.