Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

‘Hourglass’ shaped craters filled traces of glacier

18.03.2005


This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, shows flow features most likely formed by glaciers or ‘block’ glaciers.



This unusual ‘hourglass’-shaped structure is located in Promethei Terra at the eastern rim of the Hellas Basin, at about latitude 38º South and longitude 104º East. A so-called ‘block’ glacier, an ice stream with a large amount of scree (small rocks of assorted sizes), flowed from a flank of the massif into a bowl-shaped impact crater (left), nine kilometres wide, which has been filled nearly to the rim. The block glacier then flowed into a 17 kilometre wide crater, 500 metres below, taking advantage of downward slope.

The Martian surface at mid latitudes and even near the equator was being shaped by glaciers until a few million years ago. Today, water ice could still exist at shallow depths as ‘fossil’ remnants of these glaciers.


Numerous concentric ridges are visible and appear similar to ‘end moraines’ (hills of scree that form as an extending glacier pushes material ahead and remain after its retreat). Furthermore, there are parallel stripe-like structures that are interpreted as middle moraines, displaying the flow direction of these glaciers. In locations where glaciers creep over steep terrain, cracks are visible. Similarly in terrestrial glaciers, cracks are formed when tensile stress within the ice increases due to greater slope and uneven terrain.

Further glacial features include elongated grooves, extending several kilometres, and elongated hills observed on the surface of mountain ridges some distance from potentially glaciated areas. These hills could be analogous to so-called ‘drumlins’, structures formed beneath ice by glacial flow resulting in compression and accumulation of abraded material. On Earth, drumlins appear in formerly glaciated regions such as Germany’s Bavarian alpine uplands. These glacial structures are seen in a consistent spatial context, confirming the belief that scientists are really seeing former glaciers on Mars.

Of particular interest is the age of these glacially shaped surfaces, which seem to be fairly intact over a wide area of the formerly glaciated terrain. Typical evidence for a significant loss of ice volume, such as ‘kettle holes’ present in ice-free regions of Iceland, are almost entirely missing. The statistical analysis of the number of craters formed by meteorite impacts used for age determination also shows that part of the surface with its present-day glacial characteristics was formed only a few million years ago. In planetology, this age range is considered extremely young.

In these latitudes, ice on the surface of Mars is not stable over a long period of time due to the extremely thin atmosphere. In theory it is cold enough to allow for the existence of glaciers at the equator – summer day temperatures rise to a maximum of 20° C while night and winter time temperatures often drop below minus 50° C. But under the prevailing atmospheric pressure, ice would sublimate (transform directly from solid to gaseous state), and then escape from the atmosphere into outer space.

Therefore, glaciers must have formed until a few million years ago, in a time that was warmer and possibly also had a thicker atmosphere, and then became inactive or retreated due to the lack of continued supply of ice. Since then, they have been protected from sublimation by a thin dust layer. On Mars, dust is almost ubiquitous and would explain why ‘fossil’ ice present at depths of only a few metres could not be detected by other instruments such as spectrometers.

If these conclusions prove to be true, the results would indicate a climate change on Mars within the last million years. Such a dramatic climate change has been discussed for some years by Mars researchers. It could have been caused by a shift in the polar axis of the planet over millions of years – a phenomenon long known to scientists. Martian climate history is one of the main areas that ESA’s Mars Express can help to decipher.

For more information on Mars Express HRSC images, you might like to read our updated ’Frequently Asked Questions’.

Monica Talevi | alfa
Further information:
http://www.esa.int
http://www.esa.int/SPECIALS/Mars_Express/SEMN3IRMD6E_0.html

More articles from Physics and Astronomy:

nachricht Unraveling the nature of 'whistlers' from space in the lab
15.08.2018 | American Institute of Physics

nachricht Early opaque universe linked to galaxy scarcity
15.08.2018 | University of California - Riverside

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: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Staying in Shape

16.08.2018 | Life Sciences

Diving robots find Antarctic seas exhale surprising amounts of carbon dioxide in winter

16.08.2018 | Earth Sciences

Protein droplets keep neurons at the ready and immune system in balance

16.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>