"The big surprise from these new results is how pervasive and long-lasting Mars' water was, and how diverse the wet environments were," says Scott Murchie, CRISM's principal investigator at the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md.
One study, published in the July 17 issue of Nature, shows that vast regions of the ancient highlands of Mars -- which cover about half the planet -- contain clay minerals, which can form only in the presence of water. Volcanic lavas buried the clay-rich regions during subsequent, drier periods of the planet's history, but impact craters later exposed them at thousands of locations across the planet.
The clay-like minerals, called phyllosilicates, preserve a record of the interaction of water with rocks dating back to what is called the Noachian period of Mars’ history, about 4.6 billion to 3.8 billion years ago. This period corresponds to the earliest years of the solar system, when Earth, the moon and Mars sustained a cosmic bombardment by comets and asteroids. Rocks of this age have largely been destroyed on Earth by plate tectonics; they are preserved on the moon, but were never exposed to liquid water. The phyllosilicate-containing rocks on Mars therefore preserve a unique record of liquid water environments -- possibly suitable for life -- in the early solar system.
“The minerals present in Mars' ancient crust show a variety of wet environments,” says John Mustard, a member of the CRISM team from Brown University in Providence, R.I., and lead author of the Nature study. “In most locations the rocks are lightly altered by liquid water, but in a few locations they have been so altered that a great deal of water must have flushed though the rocks and soil. This is really exciting because we're finding dozens of sites where future missions can land to understand if Mars was ever habitable and if so, to look for signs of past life."
A companion study, published in the June 2 issue of Nature Geosciences, finds that the wet conditions persisted for a long time. Thousands to millions of years after the clays were formed, a system of river channels eroded them out of the highlands and concentrated them in a delta where the river emptied into a crater lake slightly larger than California’s Lake Tahoe, about 25 miles (40 kilometers) in diameter. "The distribution of clays inside the ancient lakebed shows that standing water must have persisted for thousands of years," says Bethany Ehlmann, another member of the CRISM team from Brown and lead author of the study of the ancient lake within Jezero Crater. "Clays are wonderful at trapping and preserving organic matter, so if life ever existed in this region, there's a chance of its chemistry being preserved in the delta."
CRISM’s combination of high spatial and spectral resolutions—better than any previous imaging spectrometer sent to Mars—reveals variations in the types and composition of the phyllosilicate minerals. By combining data from CRISM and MRO’s Context Imager (CTX) and High Resolution Imaging Science Experiment (HiRISE), the team has identified three principal classes of water-related minerals dating to the early Noachian period: aluminum-phyllosilicates, hydrated silica or opal, and the more common and widespread iron/magnesium-phyllosilicates. The variations in the minerals suggest that different processes, or different types of watery environments, created them.
"Our whole team is turning our findings into a list of sites where future missions could land to look for organic chemistry and perhaps determine whether life ever existed on Mars,” says APL’s Murchie.
APL, which has built more than 150 spacecraft instruments over the past four decades, led the effort to build CRISM, and operates the instrument in coordination with an international team of researchers from universities, government and the private sector. The Jet Propulsion Laboratory of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter mission for NASA’s Science Mission Directorate. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft.
The Applied Physics Laboratory, a division of the Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit http://www.jhuapl.edu. For more information on CRISM, visit http://crism.jhuapl.edu.
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26.05.2017 | University of Leicester
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24.05.2017 | Vienna University of Technology
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
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Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
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An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
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