KNOXVILLE — A team of researchers led by a University of Tennessee geologist has found geologic evidence that water existed on Mars deep in the planet’s crust.
Dr. Harry McSween discovered indications of Martian water while examining the Shergotty Stone, a meteorite found in India in 1865. The research was published in the Jan. 24 issue of Nature magazine.
“People have accepted, mostly from the rock evidence, that Mars is dry,” said McSween. “Now we are seeing evidence that Mars is actually wet, that there may even be water seeping out now.”
The team analyzed grains of mineral from the meteorite using a special mass spectrometer at Oak Ridge National Laboratory, said Dr. Rachel Lentz, a co-author and research associate in the UT geological sciences department. The team discovered that the rare elements lithium and boron were present in the core of mineral grains in the sample but were depleted from the outer layer. Lithium and boron are soluble in water.
“We concluded that the soluble elements were removed from the magma by dissolved water,” Lentz said. “This water was then lost when the magma came to the planet’s surface in a volcanic eruption.”
Magma is the molten rock deep in a planet’s crust that erupts onto the surface as lava.
The meteorite the team studied was thrown into space much later when another meteor hit the surface of Mars, sending this rock on its eventual collision course with Earth, she said.
The finding also is one of the first pieces of evidence that the water evident in Viking and Surveyor images came from the Martian interior.
McSween has studied the Shergotty meteorite for 23 years.
“It’s kind of amazing that after more than two decades we are still finding out new things from this one rock, ” he said. “It’s an indication of the increasing sophistication of the techniques available to us.”
McSween’s hypothesis is supported by the work of fellow researchers at the Massachusetts Institute of Technology, who determine experimentally that only the presence of water in the magma could explain the particular composition of the basalt rock. Scientists at the University of South Florida also participated in the research.