This implies that terrestrial planets, including Earth, have similar water sources--chondritic meteorites. However, unlike on Earth, Martian rocks that contain atmospheric volatiles such as water, do not get recycled into the planet's deep interior. Their work will be published in the December 1 issue of Earth and Planetary Science Letters. It is available online.
Much controversy surrounds the origin, abundance and history of water on Mars. The sculpted channels of the Martian southern hemisphere speak loudly of flowing water, but this terrain is ancient. Consequently, planetary scientists often describe early Mars as "warm and wet" and current Mars as "cold and dry."
Debate in the scientific community focuses on how the interior and crust of Mars formed, and how they differ from those of Earth. To investigate the history of Martian water and other volatiles, scientists at NASA's Johnson Space Center in Houston, Carnegie, and the Lunar and Planetary Institute in Houston studied water concentrations and hydrogen isotopic compositions trapped inside crystals within two Martian meteorites. The meteorites, called shergottites, were of the same primitive nature, but one was rich in elements such as hydrogen, whereas the other was depleted.
The meteorites used in the study contain trapped basaltic liquids, and are pristine samples that sampled various Martian volatile element environments. One meteorite appears to have changed little on its way from the Martian mantle up to the surface of Mars. It has a hydrogen isotopic composition similar to that of Earth. The other meteorite appears to have sampled Martian crust that had been in contact with the Martian atmosphere. Thus, the meteorites represent two very different sources of water. One sampled water from the deep interior and represents the water that existed when Mars formed as a planet, whereas the other sampled the shallow crust and atmosphere.
"There are competing theories that account for the diverse compositions of Martian meteorites," said lead Tomohiro Usui. "Until this study there was no direct evidence that primitive Martian lavas contained material from the surface of Mars."
Because the hydrogen isotopic compositions of the two meteorites differ, the team inferred that martian surface water has had a different geologic history than Martian interior water. Most likely, atmospheric water has preferentially lost the lighter hydrogen isotope to space, and has preferentially retained the heavier hydrogen isotope (deuterium).
That the enriched meteorite has incorporated crustal and atmospheric water could help to solve an important mystery. Are Martian meteorites that are enriched in components, such as water, coming from an enriched, deep mantle, or have they been overprinted by interaction with the Martian crust?
"The hydrogen isotopic composition of the water in the enriched meteorite clearly indicates that they have been overprinted, so this meteorite tells scientists more about the Martian crust than about the Martian mantle," Alexander said. "Conversely, the other meteorite yields more information about the Martian interior."
The concentrations of water in the meteorites are also very different. One has a rather low water concentration and that means that the interior of Mars is rather dry. Conversely, the enriched basalt has 10 times more water than the other one, suggesting that the surface of Mars could have been very wet at one time. Therefore, scientists are now starting to learn which meteorites tell us about the Martian interior and which samples tell us about the Martian surface.
"To understand the geologic history of Mars, more information about both of these environments is needed," Alexander said.
This workwas supported by a NASA Mars Fundamental Research Program grant, a NASA Cosmochemistry Program grant, and by a Astrobiology Institute grant ..
The Carnegie Institution for Science is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
Conel Alexander | EurekAlert!
Donuts, math, and superdense teleportation of quantum information
29.05.2015 | University of Illinois College of Engineering
Physicists precisely measure interaction between atoms and carbon surfaces
29.05.2015 | University of Washington
Many joining and cutting processes are possible only with lasers. New technologies make it possible to manufacture metal components with hollow structures that are significantly lighter and yet just as stable as solid components. In addition, lasers can be used to combine various lightweight construction materials and steels with each other. The Fraunhofer Institute for Laser Technology ILT in Aachen is presenting a range of such solutions at the LASER World of Photonics trade fair from June 22 to 25, 2015 in Munich, Germany, (Hall A3, Stand 121).
Lightweight construction materials are popular: aluminum is used in the bodywork of cars, for example, and aircraft fuselages already consist in large part of...
Using ultrashort laser pulses, scientists in Max Planck Institute of Quantum Optics have demonstrated the emission of extreme ultraviolet radiation from thin dielectric films and have investigated the underlying mechanisms.
In 1961, only shortly after the invention of the first laser, scientists exposed silicon dioxide crystals (also known as quartz) to an intense ruby laser to...
The only professorship in Germany to date, one master's programme, one laboratory with worldwide unique equipment and the corresponding research results: The University of Würzburg is leading in the field of biofabrication.
Paul Dalton is presently the only professor of biofabrication in Germany. About a year ago, the Australian researcher relocated to the Würzburg department for...
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
29.05.2015 | Life Sciences
29.05.2015 | Earth Sciences
29.05.2015 | Physics and Astronomy