A new research has found that heavy rain and huge raindrops have reshaped Mars’s impact craters and carved out river-like channels on its surface.
Billions of years ago, showers of rain were so heavy, and the raindrops were so huge.
The new study was published in the journal Icarus by geologists Robert Craddock and Ralph Lorenz. Over billions of years Mars’s atmospheric pressure fell, powering up the nature of its rainfall, study suggests.
“Many people have analyzed the nature of rainfall on the Earth, but no one had thought to apply the physics to understanding the early Martian atmosphere,” said Craddock.
After its formation around 4.5 billion years ago, soon the atmospheric pressure on the red planet was around four bars.
Craddock and Lorenz explain that at that pressure, rain would have looked more like fog. Raindrops could not have grown to more than three millimeters in diameter. So, when they struck to the ground they would not have penetrated it.
Over millions of years, as the atmospheric pressure decreased to around 1.5 bars, raindrops got bigger and rainfall became heavy. Thus, cutting into the soil and starting to alter the craters.
Lorenz said: “By using basic physical principles to understand the relationship between the atmosphere, raindrop size and rainfall intensity, we have shown that Mars would have seen some pretty big raindrops that would have been able to make more drastic changes to the surface than the earlier fog-like droplets.”
A calculation made by geologists told us that the intensity of big falls would have been only about 70% of those found on Earth. But, it would still have been easily strong enough to put a dent or two in the ground.
Of course, they suggest that the falls would have overwhelmed the soil’s ability to absorb moisture. Thus, creating run-off currents that eventually formed valley networks and reshaped impact craters.
Craddock said: “It’s unlikely that rainfall on early Mars would have been dramatically different than what’s described in our paper. Our findings provide new, more definitive, constraints about the history of water and the climate on Mars.”