Researchers studying meteorites which have reached the Earth’s surface from Mars have surveyed the water content of the Martian rocks, and concluded that the surface of Mars likely has more water than was previously estimated.
On Mars, this water is largely not found on the surface, as it is on Earth, but is locked up in the rocks beneath the ground. Mars is the fourth planet from the Sun in the solar sytem, and orbits between the Earth and far distant Jupiter.
The study was performed by Francis McCubbin, of the University of New Mexico, and Erik Hauri of the Carnegie Institution. The researchers analyzed the water content of a particular kind of meteorite, called shergottite. These meteors are believed to have been blasted from the surface of Mars in the ancient past when the planet was struck by a large impact. The debris from that impact was ejected into space and eventually found its way to the surface of the Earth.
“It’s been puzzling why previous estimates for the planet’s interior have been so dry,” co-author Erik Hauri, of the Carnegie Institution of Washington, said in a statement. “This new research makes sense and suggests that volcanoes may have been the primary vehicle for getting water to the surface.”
The Martian meteorites are believed to have formed in the planet’s mantle, the layer of the planet just under the crust. By analyzing the chemical content of the rocks, geologists can deduce the processes that formed them, and gain knowledge about Mars’ geological past. From their analysis, the team concluded that the mantle from which the meteorites was derived contained between 70 and 300 parts per million of water. The upper mantle of Earth, in comparison, contains 50 to 300 ppm of water.
The new findings, Mr. Hauri added, suggest that volcanoes may have been the primary vehicle for getting water to the Martian surface.
Moreover, the researchers are also able to measure the water content of the rocks, revealing a sample of just how wet the planet’s interior might be.
Using a technique called secondary ion mass spectrometry, the researchers estimated that the mantle material from which the rocks were blasted contained between 70 and 300 parts per million of water, which is very close to the Earth’s own content of 50 to 300 million parts per million of water. This measurement shows that, despite its dry surface, Mars’ interior appears to have a similar water content to the Earth.
Despite this watery interior, Mars has lost most of its surface water over time due to the planet’s thin atmosphere. Frozen water can be found on the planet’s surface, however, in its polar ice caps and in permafrost layers just below the surface.
Mr. McCubbin claims that these results reveal a picture of the formation of planets, “Not only does this study explain how Mars got its water, it provides a mechanism for hydrogen storage in all the terrestrial planets at the time of their formation.”
The study comes just two months before NASA is slated to land on the Red Planet. The U.S. space agency earlier this year launched its most ambitious mission to Mars, launching a massive rover capable of searching for signs of life. Curiosity is scheduled to land at approximately 10:31 p.m. PDT Aug. 5 (1:31 a.m. EDT, Aug. 6). Following checkout operations, Curiosity will begin a two-year study of whether the landing vicinity ever offered an environment favorable for microbial life.
The work was funded by NASA, the New Mexico Space Grant Consortium, and the Carnegie Institution.