What were just a few years ago small hints about Mars' water and climate, as seen in a few "postage-stamp" high-resolution images and topography, have given way to broader theory that explains not only the features seen on the planet today, but imply a dynamic history of Martian climate change.
"When you have postage stamps, it's like studying a hair on an arm instead of the whole arm," said Mars researcher James Head III of Brown University. Head will present the latest integrated global view of Martian surface features and how they fit with Martian climate models on Sunday, 28 October 2007, at the Geological Society of America Annual Meeting in Denver.
The pictures now reveal a range of ice-made features that show a strong preference to certain latitudes, Head explains. As on Earth, latitude-dependent features can mean only one thing: latitude-dependent climate.
The signs of water ice are obvious today at Mars' poles. But as you move towards the equator, there is plenty of evidence of water ice having shaped the surface in different ways not so long ago.
Not far from either pole, for instance, widespread bumpy polygonal patterned ground suggests the contraction and expansion of icy permafrost ground — very similar to that seen in Earth's Arctic and Antarctic. Next, between 30 and 60 degrees latitude in both hemispheres, the patterned ground gives way to a pervasive pitted texture of once ice-rich dust deposits. Even closer to the equator on the flanks of Mars' equatorial volcanoes are compelling signs of large glaciers, almost exactly like those of Earth. There are also craters which seem to be filled with glacial debris and small valleys which drop precipitously into canyons — which on Earth is usually a strong indicator that a glacier once filled and widened the canyon.
As for where all the ice went, much of it was sublimed away and deposited at the poles. The ice rules the more temperate latitudes only when the tilt of Mars' spin axis is far more extreme than today — up to 45 degrees. That tilt, or obliquity, exposed the poles to a lot more sun during the course of a Martian year, according to climate models, evaporating the ice caps. That same water refroze on the surface in the then darker and colder equatorial and middle latitudes, hence all the evidence of ice and glaciers.
"It's a quest to understand the Martian water cycle," said Head describing his work.
Among the instruments used to study Mars are the Mars Global Surveyor's Laser Altimeter (MOLA) and Camera (MOC), the Mars Reconnaissance Orbiter's Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE), and the Mars Express's High Resolution Stereo Camera (HRSC).WHERE & WHEN
Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation
Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences