The ice caps on Mars's poles are kilometres thick and composed of ice and dust. There are layers in the ice caps, which can be seen in cliffs and valley slopes and we have known about these layers for decades, since the first satellite images came back from Mars. The layers are believed to reflect past climate on Mars, in the same way that the Earth's climate history can be read by analysing ice cores from the ice caps on Greenland and Antarctica.
The ice cap on Mars's north pole is primarily composed of water ice and containing a few percent of dust. It has a spiral structure formed by white, ice-covered areas and dark slopes where the layers in the ice cap can be seen
Solar insolation on Mars has varied dramatically over time, mainly due to large variations in the tilt of Mars's rotational axis (obliquity) and this led to dramatic climate variations on Mars. For years people have tried to link the solar insolation and layer formation by looking for signs of periodic sequences in the visible layers, which can be seen in the upper 500 meters. Periodic signals might be traceable back to known variations in the solar insolation on Mars, but so far it has been unclear whether one could find a correlation between variations in insolation and the layers.
Correlation between ice, dust and sun
"Here we have gone in a completely different direction. We have developed a model for how the layers are built up based on fundamental physical processes and it demonstrates a correlation between ice and dust accumulation and solar insolation, explains Christine Hvidberg, a researcher in ice physics at the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
She explains that in the model the layer formation is driven by insolation and the dust rich layers can be formed by two processes: 1: Increased evaporation of ice during the summer at high obliquity (when the rotational axis tilts down) and 2: Variations in dust accumulation as a result of variations in the axial tilt. The model is simple, but physically possible and it can be used to examine the relationship between climate variability and layer formation.
The researchers established a framework for the model that could explain the layer formation so that it was consistent with the observations. By comparing the layer distribution in the model with precise measurements of the layer structure from high resolution satellite images of the ice cap on Mars's north pole, they have discovered that the model is able to reproduce the complex sequences in the layers.
Climate history over 1 million years
"The model dates the upper 500 meters of the northern ice cap on Mars, equivalent to approximately 1 million years and an average accumulation rate of ice and dust of 0.55 mm per year. It links the individual layers to the maxima in solar insolation and thereby establishes a dated climate history of the north pole of Mars over 1 million years," says Christine Hvidberg.Even though the model is only based on a comparison with the visible layers in the upper 500 meters, preliminary studies indicate that the entire thickness and internal structure of the ice cap can be explained by the model and can thus explain how ice and dust accumulation on Mars's north pole has been driven by variations in solar insolation for millions of years.
Gertie Skaarup | EurekAlert!
NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center
Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy