Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sand ripples taller on Mars

04.11.2003


Mars is kind of like Texas: things are just bigger there. In addition to the biggest canyon and biggest volcano in the solar system, Mars has now been found to have sand ripples twice as tall as they would be on Earth.

Initial measurements of some of the Red Planet’s dunes and ripples using stereo-images from the Mars Orbiter Camera onboard the Mars Global Surveyor have revealed ripple features reaching almost 20 feet high and dunes towering at 300 feet.

One way to imagine the taller dimension of ripples on Mars is to visualize sand ripples on Earth, then stretch out the vertical dimension to double height, without changing the horizontal dimension.



"They do seem higher in relation to ripples on Earth," said Kevin Williams of the Smithsonian National Air and Space Museum. Williams will be presenting this latest insight into the otherworldly scale of Marscapes on Monday, Nov. 3 at the annual meeting of the Geological Society of America in Seattle, WA.

Ripples are common on Mars and usually found in low-lying areas and inside craters, says Williams. On Earth they tend to form in long parallel lines from sand grains being pushed by water or air at right angles to the ripple lines. Dunes, on the other hand, are formed when grains of sand actually get airborne and "saltate" (a word based on the Latin verb "to jump"). That leads to cusp-shaped, star-shaped, and other dune arrangements that allow materials to pile sand much higher.

How exactly Martian dunes and ripples form is still unknown, says Williams, since the images from space give us no clues to the grain sizes or whether they are migrating or moving in any way. Though there are Viking spacecraft images from almost 30 years ago to compare with, the images do not have the resolution to confirm whether ripples have moved much in that time. For now, the dimensions of ripple-forms on Mars are the only indications of whether they are large ripples or small dunes. Williams’ results came about from the advantageous combination of image parameters to get the first height measurements of these ripple-like features at the limit of image resolution.

According to Williams, it’s likely the doubled heights of Mars ripples relative to their spacing is made possible by the same thing that makes Mars’ volcanoes so tall: lower gravity. With about one-third the gravity of Earth, sand, silt, and dust can theoretically stack up higher before gravity causes a slope failure.

However, other differences could play roles in making these large piles of sand as well. "It could also be from different wind speeds, air densities or other factors," said Williams. Mars has a perennially subfreezing, very thin atmosphere in which global dust storms have been known to obscure the surface from view.

The study of Mars dunes and ripples has been underway since Viking spacecraft images of Mars first revealed such features in the late 1970s and early 1980s, says Williams. The primary difficulty of the work continues to be in discerning the close-up details, like the exact heights of features and grain sizes. As with dunes and ripples on Earth, these wind-blown features could reveal a lot about local and regional weather and wind currents – if more was known about ripple and dune building under the very un-Earthlike conditions of Mars.

So far the only close-encounters humans have ever had with Martian dunes were with the Viking Landers and the Pathfinder mission, which sent the Sojourner rover trundling among Martian boulders. "There were some small dunes in the area of Pathfinder," Williams said.

There are also likely to be ripples or small dunes within range of the far more mobile Mars Exploration Rovers now enroute to the Red Planet, Williams said. The Mars Exploration Rovers, Spirit and Opportunity, are larger and will be able to travel much further than Sojourner, making it more likely they will be taking a closer look at ripples as well as other geological features of Mars.

Ann Cairns | EurekAlert!
Further information:
http://www.geosociety.org/
http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_63965.htm

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Cholesterol-lowering drugs may fight infectious disease

22.08.2017 | Health and Medicine

Meter-sized single-crystal graphene growth becomes possible

22.08.2017 | Materials Sciences

Repairing damaged hearts with self-healing heart cells

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>