Featured Research

from universities, journals, and other organizations

Mars: Gusev Crater once held a lake after all, scientist says

Date:
April 9, 2014
Source:
Arizona State University
Summary:
Evidence for an ancient 'Lake Gusev' on Mars has come and gone several times. That lake is looking pretty good today, thanks to new research. New research suggests floodwaters entered the crater through the huge valley that breaches Gusev's southern rim. These floods appear to have ponded long enough to alter the tephra, producing briny solutions. When the brines evaporated, they left behind residues of carbonate minerals. As the lake filled and dried, perhaps many times in succession, it loaded Comanche and its neighbor rocks with carbonates.

Comanche outcrop, seen in a mosaic of panoramic camera images from Mars rover Spirit, holds key mineralogical evidence for an ancient lake in Gusev Crater.
Credit: NASA/JPL-Caltech/Cornell University/Arizona State University

If desert mirages occur on Mars, "Lake Gusev" belongs among them. This come-and-go body of ancient water has come and gone more than once, at least in the eyes of Mars scientists.

Related Articles


Now, however, it's finally shifting into sharper focus, thanks to a new analysis of old data by a team led by Steve Ruff, associate research professor at Arizona State University's Mars Space Flight Facility in the School of Earth and Space Exploration. The team's report was just published in the April 2014 issue of the journal Geology.

The story begins in early 2004, when NASA landed Spirit, one of its two Mars Exploration Rovers, inside 100-mile-wide Gusev Crater. Why Gusev? Because from orbit, Gusev, with its southern rim breached by a meandering river channel, looked as if it once held a lake -- and water-deposited rocks were the rover mission's focus. Yet, when Spirit began to explore, scientists found Gusev's floor was paved not with lakebed sediments, but volcanic rocks.

Less than two miles away however, stood the Columbia Hills, 300 feet high. When Spirit drove up into them, it indeed discovered ancient rocks that had been altered by water. But to scientists' chagrin, no lake sediments were among them. Instead, scientists discovered evidence of hydrothermal activity -- essentially hot springs like those in Yellowstone National Park.

But there's hope yet for Lake Gusev, thanks to a Columbia Hills rock outcrop, dubbed Comanche. This outcrop is unusually rich in magnesium-iron carbonate minerals, a discovery made in 2010 that Ruff played a major role in. While Comanche's carbonate minerals were originally attributed to hydrothermal activity, the team's new analysis points to a different origin.

Cool waters

Says Ruff, "We looked more closely at the composition and geologic setting of Comanche and nearby outcrops. There's good evidence that low temperature surface waters introduced the carbonates into Comanche rather than hot water rising from deep down."

Comanche started out as a volcanic ash deposit known as tephra that originally covered the Columbia Hills and adjacent plains. This material, Ruff explains, came from explosive eruptions somewhere within or around Gusev.

Then floodwaters entered the crater through the huge valley that breaches Gusev's southern rim. These floods appear to have ponded long enough to alter the tephra, producing briny solutions. When the brines evaporated, they left behind residues of carbonate minerals. As the lake filled and dried, perhaps many times in succession, it loaded Comanche and its neighbor rocks with carbonates.

"The lake didn't have to be big," Ruff explains. "The Columbia Hills stand 300 feet high, but they're in the lowest part of Gusev. So a deep, crater-spanning lake wasn't needed."

Today, the Columbia Hills rise as an island of older terrain surrounded by younger lava flows, Ruff says. "Comanche and a neighbor outcrop called Algonquin are remnants of the older and much more widespread tephra deposit. The wind has eroded most of that deposit, also carrying away much of the evidence for an ancient lake."

Return to Gusev?

Mars rover Spirit fell silent on a winter night in March 2010, and it has never been heard from since. Spirit left most of the Columbia Hills and other Gusev targets unexplored. Ruff says that as NASA evaluates landing sites for its new sample-collecting rover in 2020, Gusev Crater deserves serious consideration.

"Going back to Gusev would give us an opportunity for a second field season there, which any terrestrial geologist would understand," argues Ruff. "After the first field season with Spirit, we now have a bunch more questions and new hypotheses that can be addressed by going back."

Because the Mars 2020 rover mission will collect and cache samples for potential return to Earth, that makes going to an already visited site more important, says Ruff.

"Scientifically and operationally it makes sense to go to a place which we know has geologically diverse -- and astrobiologically interesting -- materials to sample," Ruff argues.

"And we know exactly where to find them."


Story Source:

The above story is based on materials provided by Arizona State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. W. Ruff, P. B. Niles, F. Alfano, A. B. Clarke. Evidence for a Noachian-aged ephemeral lake in Gusev crater, Mars. Geology, 2014; 42 (4): 359 DOI: 10.1130/G35508.1

Cite This Page:

Arizona State University. "Mars: Gusev Crater once held a lake after all, scientist says." ScienceDaily. ScienceDaily, 9 April 2014. <www.sciencedaily.com/releases/2014/04/140409155744.htm>.
Arizona State University. (2014, April 9). Mars: Gusev Crater once held a lake after all, scientist says. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2014/04/140409155744.htm
Arizona State University. "Mars: Gusev Crater once held a lake after all, scientist says." ScienceDaily. www.sciencedaily.com/releases/2014/04/140409155744.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Space & Time News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Spokesman: 'NORAD Ready to Track Santa'

Spokesman: 'NORAD Ready to Track Santa'

AP (Dec. 19, 2014) Pentagon spokesman Rear Adm. John Kirby said that NORAD is ready to track Santa Claus as he delivers gifts next week. Speaking tongue-in-cheek, he said if Santa drops anything off his sleigh, "we've got destroyers out there to pick them up." (Dec. 19) Video provided by AP
Powered by NewsLook.com
NASA's Planet-Finding Kepler Mission Isn't Over After All

NASA's Planet-Finding Kepler Mission Isn't Over After All

Newsy (Dec. 18, 2014) More than a year after NASA declared the Kepler spacecraft broken beyond repair, scientists have figured out how to continue getting useful data. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Reuters - US Online Video (Dec. 16, 2014) NASA's Mars Curiosity rover finds methane in the Martian atmosphere and organic chemicals in the planet's soil, the latest hint that Mars was once suitable for microbial life. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins