Free Newsletters - Space - Defense - Environment - Energy
. Mars Exploration News .

Ancient snowfall likely carved Martian valleys
by Staff Writers
Providence RI (SPX) Jul 24, 2013

Water-carved valleys on Mars appear to have been caused by runoff from precipitation, likely meltwater from snow. Early Martian precipitation would have fallen on mountainsides and crater rims. Credit: Images from NASA.

Valley networks branching across the Martian surface leave little doubt that water once flowed on the Red Planet. But where that ancient water came from - whether it bubbled up from underground or fell as rain or snow - is still debated by scientists. A new study by researchers at Brown University puts a new check mark in the precipitation column.

The study finds that water-carved valleys at four different locations on Mars appear to have been caused by runoff from orographic precipitation - snow or rain that falls when moist prevailing winds are pushed upward by mountain ridges. The new findings are the most detailed evidence yet of an orographic effect on ancient Mars and could shed new light on the planet's early climate and atmosphere.

A paper describing the work has been accepted by Geophysical Research Letters and published online in June.

Kat Scanlon, a geological sciences graduate student at Brown, led the research and is well-acquainted with the orographic effect. She did graduate work in meteorology in Hawaii, which is home to a quintessential orographic pattern. Moist tropical winds from the east are pushed upward when they hit the mountains of Hawaii's big island.

The winds lack the kinetic energy to reach the mountain summit, so they dump their moisture on the eastern side of the island, making parts of it a tropical jungle. The western side, in contrast, is nearly a desert because it sits in a rain shadow cast by the mountain peak.

Scanlon thought similar orographic patterns might have been at play on early Mars and that the valley networks might be an indicator. "That's what immediately came to mind in trying to figure out if these valleys on Mars are precipitation related," she said.

The researchers, including Jim Head, professor of geological sciences, started by identifying four locations where valley networks were found along tall mountain ridges or raised crater rims. To establish the direction of the prevailing winds at each location, the researchers used a newly developed general circulation model (GCM) for Mars.

The model simulates air movement based on the gas composition scientists think was present in the early Mars atmosphere. Next, the team used a model of orographic precipitation to determine where, given the prevailing winds from the GCM, precipitation would be likely to fall in each of the study areas.

Their simulations showed that precipitation would have been heaviest at the heads of the densest valley networks. "Their drainage density varies in the way you would expect from the complex response of precipitation to topography," Scanlon said. "We were able to confirm that in a pretty solid way."

The atmospheric parameters used in the GCM are based on a new comprehensive general circulation model that predicts a cold climate, so the precipitation modeled in this study was snow. But this snow could have been melted by episodic warming conditions to form the valley networks, and indeed some precipitation could have been rain during this period, Scanlon and Head say.

"The next step is to do some snowmelt modeling," she said. "The question is how fast can you melt a giant snowbank. Do you need rain? Is it even possible to get enough discharge [to carve the valleys] with just the snowmelt?"

With the knowledge from this study that precipitation was important in carving the valleys, the answers to those additional questions could provide important insight into the climate on Mars billions of years ago.


Related Links
Brown University
Mars News and Information at
Lunar Dreams and more

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Marks on Martian Dunes May Reveal Tracks of Dry-Ice Sleds
Tucson AZ (SPX) Jun 13, 2013
NASA research indicates that hunks of frozen carbon dioxide - or dry ice - may glide down some Martian sand dunes on cushions of gas similar to miniature hovercraft, plowing furrows as they go. Researchers deduced this process could explain one enigmatic class of gullies seen on Martian sand dunes by examining images from NASA's Mars Reconnaissance Orbiter, or MRO, and performing experimen ... read more

First-ever lunar south pole mission could be attempted by 2016

Engine recovered from Atlantic confirmed as Apollo 11 unit

Soviet Moon rover moved farther than thought

Scientist says Earth may once have been orbited by two moons

China launches three experimental satellites

Medical quarantine over for Shenzhou-10 astronauts

China's astronauts ready for longer missions

Chinese probe reaches record height in space travel

NASA launches new probe of spacesuit failure

Space Station ARISS Software Upgraded by Student For Students

Astronaut's helmet leak forces abrupt end to spacewalk

NASA puzzled as astronaut's helmet leak halts spacewalk

SciTechTalk: Grab your erasers, there are more moons than we thought

NASA Hubble Finds New Neptune Moon

NASA finds new moon on Neptune

A Giant Moon for the Ninth Planet

Revealed - the mystery of the gigantic storm on Saturn

Cassini Finds Hints of Activity at Saturn Moon Dione

Wild Weather Could Be Ahead on Titan

Cassini Shapes First Global Topographic Map of Titan

First high-resolution national carbon map - Panama

NASA Releases Images of Earth Taken by Distant Spacecraft

e2v and Astrium sign contract for imaging sensors to equip the Sentinel 4 satellite

The First Interplanetary Photobomb

Boeing CST-100 Spacecraft Model Passes Water-Recovery Tests

NASA announces funding for far-out space research

The Zero Gravity Coffee Cup

Outside View: Future science fiction

Snow falling around infant solar system

'Water-Trapped' Worlds

A snow line in an infant solar system: Astronomers take first images

In the Zone: The Search For Habitable Planets

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement