A new study of magma-formed Martian clay by French and US scientists suggests that Mars possibly never had free-flowing water. The new study contradicts previous studies that suggested the early environment of Mars had water believed essential for life.
Previous NASA surveys revealed ice at the Martian poles and evidence of valleys created by flowing water in the early geological era of Mars' history. NASA's surveys also revealed clay deposits that appear to have been formed by free-flowing water. According to Space.com, planetary geologists have for decades assumed that Martian clay deposits were formed from large bodies of waters that once existed on the planet. For long, scientists have associated clay deposits with water because on Earth, clays are frequently found in riverbeds, close to glaciers and oceans, Space.com reports. Clay material near water sources is formed over a long time from weathered rock. Thus, scientists have taken the presence of clay on Mars as evidence that its ancient environment had long-standing bodies of water. According to research scientist Alan Meunier of the Université de Poitiers in France, "Considering that clays witness the presence of liquid water, they implied that the physical conditions prevailing at the surface of the young planet were compatible with the liquid state."
Universe Today reports that a group of geologists led by Alan Meunier of the Université de Poitiers in France and Bethan Ehlman, planetary geologist at Caltech, discovered that iron and magnesium rich clay, similar to Martian clay found at the Moruroa atoll in French Polynesia, could form rapidly from cooling magma. The researchers, therefore, concluded that the types of clay found on Mars could have been formed from magma in a volcanic environment rather from weathered rock close to a water source.
Magmatic clay, as it is called, has also been found in the Parana Basin of Brazil. The Daily Mail reports the researchers say light signature of Earth clays formed from magma are similar to some of the Martian clays found on meteorites that originated from Mars. The samples of clay on Earth that originated from Mars were derived from rocks, such as the Lafayette Meteorite, propelled into space by meteor impacts.
Meunier explained to AFP: “To crystallise, clays need water but not necessarily liquid water. In other words, clays are not exclusively typical of soils or altered rocks; they may crystallise also directly from magmas." He continued: “Magmatic clays have no climatic significance. Consequently, they cannot be used to prove that the planet was habitable or not during its early history.”
According to the study published in Nature Geoscience, clay may have formed on Mars from lava at high temperatures of 1,500C. Universe Today reports that the researchers said that because the Martian clay deposits are often hundreds of meters thick, they were likely formed from magma.
Space.com reports Meunier, said: "It was the first time that clays were shown to originate from another process than aqueous alteration.The consequence was that, even if clays need water to be formed, this does not mean that they need liquid water."
Brian Hynek, of the Department of Geological Sciences at the University of Colorado, who was not involved in the study, but wrote a paper commenting on it, said: "The authors demonstrate pretty convincing evidence that some of the water that led to clay formation was derived from the magmatic gases" (Nature Geoscience).
NASA / JPL / MSSS
Lava swirls in a channel in Cerberus Palus, Mars
The Daily Mail notes that here on Earth, magmatic clay may carry life because of the generally favorable conditions on the planet, but on Mars, wide distribution of magmatic clay suggests that the ancient environment of the Red Planet was different from what scientists have thought. Space.com reports Meunier said: "The possibility of a magmatic origin for clays changes these considerations," that is, ancient Mars was probably hostile to life.
According to LA Times, planetary scientist Ralph Miliken, said the new study claim has "some merit." He said: "It's certainly a different take on trying to explain the origin of some clay minerals on Mars. It does have some merit, and alternative hypotheses need to be considered fully." However, Miliken said that there were other bodies of evidence that appear to contradict the suggestion. For instance, certain geological tracks and mineral deposits on the planet are believed to have been formed by moving water.
Space.com reports that Brian Hynek, of the Department of Geological Sciences at the University of Colorado, noted that not all meteorites from Mars appear to have formed from magma and that only a few samples of Martian meteorites that come from a limited era of Martian history are available for study. Scientists, therefore, still believe that even if the early Martian environment was dry, there appears to be evidence that water existed on the planet at a later period. AFP reports that recently, a study suggested that a huge sea probably covered more than a third of the Martian surface at a time single-cell life forms were evolving on Earth.
Image credit: NASA/JPL-Caltech/University of Arizona
Images like this from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter show portions of the Martian surface in unprecedented detail.
Although Universe Today reports Hyneck wrote: “[This] new hypothesis proposes that the minerals instead formed during brief periods of magmatic degassing, diminishing the prospects for signs of life in these settings,” Space.com reports he later qualified his statement, saying: "I don't think this new research changes our general picture of early Mars. It just provides an additional mechanism for forming clay minerals."
Scientists believe that NASA's rover Curiosity will bring more evidence to light as it investigates the planet.