Martian valleys carved by less ancient water
9 Dec 2015 by qwbdchbctt.d qwbdchbctt.d
Martian valleys could have been carved by much less water in a much shorter time span than previously thought.
Martian valleys could have been carved by much less water in a much shorter time span than previously thought.
Scientists at Brown University studied the southern highlands of Mars and found that that the minimum water volume required to carve the valleys could have flowed through in as little as a few hundred to 10,000 years rather than millions of years. These findings are consistent with the idea that early Mars may have been a cold and icy planet with flowing surface water in response to short-term climate changes.
Research associate Professor Jim Head said: “The valley networks represent much of the evidence for why many scientists think ancient Mars was warm and wet, which implies that there was a lot of water flowing for a long period of time — perhaps millions of years.
“But this analysis suggests that the valleys could have been carved by a smaller volume of water over a potentially shorter period of time. That gives us guidance about trying to understand what was really going on with the early Mars climate.”
In the study, published in the journal Planetary and Space Science, the team used data from the Mars Orbiter Laser Altimeter (MOLA) to get the average cross-section for the valleys and to calculate their sediment volume. By looking at the morphology of the valleys they estimated that the depth of ancient Martian rivers in the area may have been between 1m and 16m deep with a minimum grain size of 1mm-6.2mm. To confirm their theoretical approach, scientists compared the grain sizes yielded by the theoretical calculations with the grain sizes the Curiosity rover found in Gale Crater and found a close match.
This allowed the team to estimate the volume of Martian rivers. Their calculations showed that water volume that flowed through the valleys is equal to global layer depths between three and 100m in a few hundred years to 10,000 years.
“This means that the amount of water that we calculate may have flowed through the valleys is on the same order as the amount of water on the planet today. The implication here is that the valleys may well have been carved by a much smaller volume of water than many people previously thought,” said Professor Head.
Paper: http://www.sciencedirect.com/science/article/pii/S0032063315002457
