Researchers probed Martian meteorites to reconstruct Mars’ chaotic history. Their findings suggest that Mars might not have had a global magma ocean.
Barnes is an assistant professor of planetary sciences in the University of Arizona Lunar and Planetary Laboratory. She and her team chemically analyzed the Black Beauty meteorite and the infamous Allan Hills 84001 meteorite — controversial in the 1990s for allegedly containing Martian microbes — to reconstruct Mars’ water history and planetary origins.
Their analysis, published today in Nature Geoscience, showed that Mars likely received water from at least two vastly different sources early in its history. The variability the researchers found implies that Mars, unlike Earth and the moon, never had an ocean of magma completely encompassing the planet.
«These two different sources of water in Mars’ interior might be telling us something about the kinds of objects that were available to coalesce into the inner, rocky planets,» Barnes said. Two distinct planetesimals with vastly different water contents could have collided and never fully mixed. «This context is also important for understanding the past habitability and astrobiology of Mars.»
Reading the Water
«A lot of people have been trying to figure out Mars’ water history,» Barnes said. «Like, where did water come from? How long was it in the crust (surface) of Mars? Where did Mars’ interior water come from? What can water tell us about how Mars formed and evolved?»
Barnes and her team were able to piece together Mars’ water history by looking for clues in two types, or isotopes, of hydrogen. One hydrogen isotope contains one proton in its nucleus; this is sometimes called «light hydrogen.» The other isotope is called deuterium, which contains a proton and a neutron in the nucleus; this is sometimes referred to as «heavy hydrogen.» The ratio of these two hydrogen isotopes signals to a planetary scientist the processes and possible origins of water in the rocks, minerals and glasses in which they’re found.
Story Source: Materials provided by University of Arizona. Original written by Mikayla Mace. Note: Content may be edited for style and length.