The results were obtained by MARSIS, the pioneering sounding radar on board ESA’s Mars Express orbiter, and provide important new clues about the still mysterious geological history of Mars.
Observations by MARSIS, the first sub-surface sounding radar used to explore a planet, strongly suggest that ancient impact craters lie buried beneath the smooth, low plains of the northern hemisphere of Mars. The technique uses echoes of radio waves that have penetrated below the surface.
MARSIS found evidence that these buried impact craters – from about 130 to 470 kilometres in diameter – are present under much of the northern lowlands. The findings appear in the 14 December issue of the journal Nature.
With MARSIS "it's almost like having X-ray vision," said Thomas R. Watters of the National Air and Space Museum's Center for Earth and Planetary Studies, Washington, and lead author of the results. "Besides finding previously unknown impact basins, we've also confirmed that some subtle, roughly circular, topographic depressions in the lowlands are related to impact features."
Studies of how Mars evolved aid understanding of early Earth. Some signs of the forces at work a few thousand million years ago are harder to detect on Earth because many of them have been obliterated by tectonic activity and erosion.
The new findings bring planetary scientists closer to understanding one of the most enduring mysteries about the geologic evolution and history of Mars. In contrast to Earth, Mars shows a striking difference between its northern and southern hemispheres. Almost the entire southern hemisphere has rough, heavily cratered highlands, while most of the northern hemisphere is smoother and lower in elevation.
Since the impacts that cause craters can happen anywhere on a planet, the areas with fewer craters are generally interpreted as younger surfaces where geological processes have erased the impact scars. The surface of Mars' northern plains is young and smooth, covered by vast amounts of volcanic lava and sediment. However, the new MARSIS data indicate that the underlying crust is extremely old.
“The number of buried impact craters larger than 200 kilometres in diameter that we have found with MARSIS,” said Jeffrey Plaut, MARSIS co-Principal Investigator, from the Jet Propulsion Laboratory, California, “tells us that the underlying crust in the northern lowlands must be very ancient, dating to the Early Noachian epoch (lasting from the planet's birth to about 4 thousand million years ago).” The Early Noachian was an era in which impact cratering was very intense across the Solar System.
The results suggest that the northern lowlands crust is as old as the as the oldest exposed southern highlands, also dated in the Noachian epoch, and that the dichotomy between northern and southern hemispheres probably formed very early in the history of Mars.
“These results are truly interesting and unprecedented,” added Giovanni Picardi, MARSIS Principal Investigator, from the University of Rome ‘La Sapienza’. “MARSIS can contribute to understand the geology of Mars through the analysis of the surface and sub-surface morphology. In addition, with a detailed analysis of the instrument’s data, we can also obtain valuable indications about the composition of the materials.”
ESA Media Relations Office | alfa
Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst
Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center
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...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
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