Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Orbiter provides new hints of past groundwater flows on Mars

19.02.2007
A spacecraft recently arrived at Mars has provided new evidence that fluids, likely including water, once flowed widely through underlying bedrock in a canyon that is part of the great Martian rift valley.

The new color images from the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter show an equatorial landscape of hills composed of dozens of alternating layers of dark- and light-toned rocks, and crossed by dark sand dunes.

Within those layered deposits, the exquisitely detailed images show, there are a series of linear fractures, called joints, that are surrounded by "halos" of light-toned bedrock. In a paper to be published 16 February in the journal Science, published by the American Association for the Advancement of Science (AAAS), researchers argue that the "halos" offer clear evidence of past fluid flow through the bedrock.

Minerals in the fluid acted like cement to strengthen and bleach the rock, they say. The cemented rock proved more resistant to wind erosion than other features on the canyon walls and floor. It now serves as an exposed record of hydrological activity and offers a promising site to search for evidence of habitable niches in the Martian past.

Chris H. Okubo, the principal author of the paper and a postdoctoral researcher at the University of Arizona's Lunar and Planetary Laboratory, said the new images strongly suggest that subsurface fluids -- probably water, liquid carbon dioxide or a combination of the two -- once flowed abundantly in the western Candor Chasma region of Mars.

Okubo will discuss the paper during a 15 February news briefing at the 2007 AAAS Annual Meeting in San Francisco. The briefing also will include speakers from a 16 February Annual Meeting symposium on "The New Mars: Habitability of a Neighbor World."

Candor Chasma is one of several canyons that make up the great Martian rift valley called Valles Marineris. The rift valley would extend across the United States and is 6 to 7 times deeper than the Grand Canyon in places. It is the deepest gash on any planet in the solar system.

The linear fractures photographed by HiRISE (the High Resolution Imaging Science Experiment) are hundreds of meters to several kilometers in length. The origin of the joints remains a mystery, Okubo said. But once formed, they provided a pathway for substantial flows from an underground reservoir of some kind. The timing of the flows remains uncertain, Okubo said, but could have occurred many millions or several billions of years ago.

"The fractures helped to increase the fluid flow through this area," Okubo said. And the associated halos of light-colored rocks suggest a familiar mechanism of action.

"On Earth, bleaching of rock surrounding a fracture is a clear indication of chemical interactions between fluids circulating within the fracture and the host rock," write Okubo and his co-author, Alfred S.McEwen. McEwen is a professor of planetary science at the University of Arizona and principal investigator for HiRISE.

McEwen said the fluid very likely was water, a key ingredient in any scenario for past or present life on Mars. Direct analysis of the chemical composition of the rock by future Mars rovers could confirm that, he said.

In the meantime, NASA's Opportunity rover, which has been roaming the Martian surface for three years, is now exploring the layered deposits exposed by Victoria Crater. That crater sits on a vast plain just south of the Martian equator. Scientists believe the layered deposits in the crater may have been formed by fluid processes similar to those at work in the Candor Chasma region photographed by the HiRISE camera. HiRISE images of Victoria Crater revealed structures along the eastern slopes of the crater that the authors believe could have formed from fluid motion along fractures, as in Candor Chasma.

Layered deposits have intrigued scientists since they first were discovered by the Mariner 9 and Viking orbiters in the 1970s. "The origin, history and nature of the light-toned, layered deposits are of great interest," McEwen said. "There has been lots of debate about the significance of these materials."

The layered outcrops suggest cycles of change in which materials were deposited in regular episodes of water, wind or volcanic activity. Scientists have debated whether the layered features in the Candor Chasma region were formed before or after the chasm opened up.

The HiRISE camera can detect surface features that are less than the size of a pixel, or about one foot across. That sort of resolution has allowed images of layered deposits with exceptional clarity and is providing new clues on the history and origin of the deposits.

The photos discussed in the Science paper were taken as part of an initial set of about 60 test images shortly after the Mars Reconnaissance Orbiter reached its final mapping orbit last fall. "We knew this region of Candor Chasma contained hydrated minerals," McEwen said. It had been observed previously by an instrument aboard the European Mars Express orbiter, which found spectral signatures for water-associated minerals called hydrated sulfates (including perhaps epsomite, a key ingredient in bath salts.)

In reviewing the first HiRISE images of the canyon, Okubo said, "We saw something very interesting," the first detailed evidence for cemented joints in the region. The spacecraft subsequently has found even more of the joints. (If rock is brittle, it can be laced with cracks. If the fractures or breaks occur where movement has taken place, such as seismic activity, they are called faults. If the cracks occur without movement --typically because of tension forces in the rock -- they are called joints.)

Organizers of the Mars symposium at the AAAS Annual Meeting note that Mars is the only other planet in the solar system that appears to have once had a habitable climate similar to that of Earth. Recent missions, now including the Mars Reconnaissance Orbiter, have returned ample evidence suggesting that early Mars had an active hydrological cycle, with streams, lakes, precipitation and groundwater flows. There even have been Mars Global Surveyor images, published in Science in December, suggesting that water may have flowed briefly in two Martian gullies within the past few years.

Much of the attention in the "follow the water" strategy had been devoted to features that appear to be dry lake or river beds. The new HiRISE images demonstrate that exposed joints and faults in underlying bedrock also may provide valuable new information on the history of Martian hydrology and geology, according to Okubo and McEwen.

Earl Lane | EurekAlert!
Further information:
http://www.aaas.org

More articles from Physics and Astronomy:

nachricht Basque researchers turn light upside down
23.02.2018 | Elhuyar Fundazioa

nachricht Attoseconds break into atomic interior
23.02.2018 | Max-Planck-Institut für Quantenoptik

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>