30 mile crater on Mars reveals ancient water resevoir

Meteor impact that gouged 30-mile crater on Mars reveals traces of ancient reservoir

• Crater reveals layers thought to have been carved by groundwater reservoir
• Lends weight to idea that Mars was once very different
• Mars has 'undergone radical climate change'

By ROB WAUGH
Daily Mail
June 8, 2012

Two side-by-side meteor craters on Mars have revealed that the Red Planet has undergone serious climate change in its history.

One crater in particular reveals dark traces of sediment thought to have been cemented together by water from an ancient groundwater reservoir, before being carved away by howling Martian wind.

The find, by the European Space Agency's Mars Express orbiter, has lent weight to the idea that Mars was once very different to the dead orb we see now.

One crater in particular reveals dark traces of sediment thought to have been cemented together by water from an ancient groundwater reservoir, before being carved away by howling Martian wind. Image credit: ESA

The ancient 'climate change' that turned Mars from a wet planet - possibly capable of supporting life - to the dusty, wind-scoured orb that we see today was probably caused by changes in the axis of the planet's rotation.

Similar forces are thought to have an impact on the cycle of ice ages on Earth.
On 19 June 2011, Mars Express pointed its high-resolution stereo camera at the Arabia Terra region of Mars, imaging the Danielson and Kalocsa craters.

Danielson crater is named after the late George E. Danielson, who was instrumental in the development of many spacecraft cameras flown to Mars, and is 40 miles across.

Kalocsa crater lies in the center of the image and is smaller, about 20 miles in diameter.
Danielson crater, like many in the Arabia Terra region, is filled with layered sediments, which in this instance have been heavily eroded over time. Within the crater are peculiarly layered buttes, known as yardangs.

The find, by the European Space Agency's Mars Express orbiter, has lent weight to the idea that Mars was once very different to the dead orb we see now. Image credit: ESA

Yardangs are streamlined hills carved from bedrock or any consolidated or semi-consolidated material by abrasive dust and sand particles carried in the wind.

They are seen on Earth in desert regions, with notable examples in North Africa, Central Asia and Arizona in the United States.

In the case of Danielson crater, it is believed that sediments were cemented by water, possibly from an ancient deep groundwater reservoir, before being eroded by the wind.

The orientation of the yardangs leads scientists to theorize that strong north-northeasterly winds (from the lower right in the image) both deposited the original sediments and then caused their erosion.

Oceans once existed on Mars...More evidence mounting the red planet once being wet

Mars Express Radar Yields Strong Evidence of Ocean That Once Covered Part of Red Planet
ScienceDaily
February 7, 2012

 — ESA's Mars Express has returned strong evidence for an ocean once covering part of Mars. Using radar, it has detected sediments reminiscent of an ocean floor within the boundaries of previously identified, ancient shorelines on Mars.

The MARSIS radar was deployed in 2005 and has been collecting data ever since. Jérémie Mouginot, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) and the University of California, Irvine, and colleagues have analysed more than two years of data and found that the northern plains are covered in low-density material.

(Image above): New results from the MARSIS radar on Mars Express give strong evidence for a former ocean of Mars. The radar detected sediments reminiscent of an ocean floor inside previously identified, ancient shorelines on the red planet. The ocean would have covered the northern plains billions of years ago. Credits: ESA, C. Carreau

"We interpret these as sedimentary deposits, maybe ice-rich," says Dr Mouginot. "It is a strong new indication that there was once an ocean here."

The existence of oceans on ancient Mars has been suspected before and features reminiscent of shorelines have been tentatively identified in images from various spacecraft. But it remains a controversial issue.

Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted, possibly as a result of enhanced geothermal activity, creating outflow channels that drained the water into areas of low elevation.

"MARSIS penetrates deep into the ground, revealing the first 60-80 metres of the planet's subsurface," says Wlodek Kofman, leader of the radar team at IPAG.

"Throughout all of this depth, we see the evidence for sedimentary material and ice."

The sediments revealed by MARSIS are areas of low radar reflectivity. Such sediments are typically low-density granular materials that have been eroded away by water and carried to their final destination.

This later ocean would however have been temporary. Within a million years or less, Dr Mouginot estimates, the water would have either frozen back in place and been preserved underground again, or turned into vapour and lifted gradually into the atmosphere.

"I don't think it could have stayed as an ocean long enough for life to form."
In order to find evidence of life, astrobiologists will have to look even further back in Mars' history when liquid water existed for much longer periods.


Image: Mars Express has used its MARSIS radar to give strong evidence for a former ocean of Mars. The radar was deployed on the spacecraft in 2005 and has been collecting data from the subsurface ever since. Credits: ESA, C. Carreau

Nevertheless, this work provides some of the best evidence yet that there were once large bodies of liquid water on Mars and is further proof of the role of liquid water in the martian geological history."Previous Mars Express results about water on Mars came from the study of images and mineralogical data, as well as atmospheric measurements. Now we have the view from the subsurface radar," says Olivier Witasse, ESA's Mars Express Project Scientist.

"This adds new pieces of information to the puzzle but the question remains: where did all the water go?"

Mars Express continues its investigation.

Story Source:
The above story is reprinted from materials provided by European Space Agency.

Journal Reference:
Jérémie Mouginot, Antoine Pommerol, Pierre Beck, Wlodek Kofman, Stephen M. Clifford. Dielectric map of the Martian northern hemisphere and the nature of plain filling materials. Geophysical Research Letters, 2012; 39 (2) DOI: 10.1029/2011GL050286

View Martian clouds in motion over Noachis Terra

From: planetsocblog | Aug 19, 2011

The images that compose this animation were taken on October 14, 2010, on Mars Express' 8676th orbit, and show an area within Noachis Terra to the west of Hellas basin, around 45 degrees south, 38 east. There are two components to the apparent motions of the clouds. One is real west-to-east cloud motion over the two-minute period of the animation (readable from the motions of the shadows along the ground). The other component has to do with the different look angles of the different channels of HRSC and the significant thickness of the cloud layer. In the first frame, HRSC was looking forward (northward) along its south-to-north orbital path; in the last frame, it was looking backward (southward). Because of this changing perspective, the upper-level clouds appear to move southward with respect to the lower-level clouds.

The color comes from red, green, and blue channels of the HRSC channel and is an overlay applied to the animation, so the color information is actually not animated -- only the brightness information moves. This works visually because Mars is relatively monochromatic

http://www.youtube.com/user/planetsocblog#p/u/9/znYh6j0Tl3o