As NASA prepares to launch a new Martian probe, a MagLab scientist has uncovered what may be the first recognized example of ancient Martian crust. Florida State University Professor Munir Humayun’s groundbreaking discoveries about the crust and what it reveals about the Red Planet’s origins were published this week in Nature.
Humayun’s work is based on an analysis of a 4.4 billion-year-old Martian meteorite that was unearthed by Bedouin tribesmen in the Sahara desert. The rock (NWA 7533) may be the first recognized sample of ancient Martian crust and holds a treasure chest of information about the origin and age of the Red Planet’s crust.
In order to detect minute amounts of chemicals in this meteorite, Humayun and his collaborators performed complex analysis on it using an array of highly sophisticated mass spectrometers in the MagLab’s geochemistry department. High concentrations of trace metals such as iridium, an element that indicates meteoritic bombardment, showed that this meteorite came from the elusive cratered area of Mars’ southern highlands.
“This cratered terrain has been long thought to hold the keys to Mars’ birth and early childhood,” said Humayun, a professor in FSU’s Department of Earth, Ocean and Atmospheric Science.
While craters cover more than half of Mars, this is the first meteoric sample to come from this area, bringing the first opportunity for researchers to understand Mars’ early crystal growth.
Using the chemical information found in pieces of soil contained in the meteorite, Humayun was able to calculate the thickness of Mars’ crust. His calculation aligned with estimates from independent spacecraft measurements and confirms that Mars did not experience a giant impact that melted the entire planet in its early history.
Using a powerful microprobe at Curtin Univ. in Perth, Australia, the team dated special crystals within the meteorite—called zircons—at an astounding 4.4 billion years old.
“This date is about 100 million years after the first dust condensed in the solar system,” Humayun said. “We now know that Mars had a crust within the first 100 million years of the start of planet building, and that Mars’ crust formed concurrently with the oldest crusts on Earth and the Moon.”
Humayun and his collaborators hypothesize that these trailblazing discoveries are just the tip of the iceberg of what continued research on this unique meteorite will uncover. Further studies may reveal more clues to the impact history of Mars, the nature of Martian zircons and the makeup of the earliest sediments on the Red Planet.
Humayun’s international team of collaborators include curator of meteorites Brigitte Zanda with the National Museum of Natural History (the Muséum National d’Histoire Naturelle) in Paris; A. Nemchin, M. Grange and A. Kennedy with Curtin University’s Department of Applied Geology in Perth, Australia; and scientists R. H. Hewins, J. -P. Lorand, C. Göpel, C. Fieni, S. Pont and D. Deldicque.
Origin and age of the earliest Martian crust from meteorite NWA7533
Source: MagLab, Florida State Univ.