Analysis of a Martian meteorite shows evidence of water 4.4 billion years ago
IMAGE: MARTIAN METEORITE NWA 7533 is worth more than its weight in gold. See more CREDIT: © NASA / LUC LABENNE
In planetary research there has been a longstanding question about the origin of water on Earth, Mars and other large bodies such as the moon. One hypothesis is that it came from asteroids and comets after formation. However, some planetary researchers believe that water may be just one of many substances that naturally occur in the formation of planets. A new analysis of an old Martian meteorite supports this second hypothesis.
A few years ago, two dark meteorites were discovered in the Sahara. They were named NWA 7034 and NWA 7533, where NWA stands for North West Africa and the number is the order in which meteorites are officially approved by the Meteoritical Society, an international organization for planetary science. The analysis revealed that these meteorites are new types of Martian meteorites and are mixtures of different rock fragments.
The earliest fragments, which formed on Mars 4.4 billion years ago, make them the oldest known Martian meteorites. Stones like this one are rare and can fetch up to $ 10,000 per gram. Recently, 50 grams of NWA 7533 was purchased for analysis by the international team that included Professor Takashi Mikouchi from the University of Tokyo.
“I study minerals in Martian meteorites to understand how Mars formed and how its crust and mantle developed. This is the first time I have examined this particular meteorite, nicknamed Black Beauty, for its dark color, ”said Mikouchi. “Our samples from NWA 7533 were subjected to four different types of spectroscopic analysis to detect chemical fingerprints. The results have led our team to some exciting conclusions. "
Planetary scientists know that there has been water on Mars for at least 3.7 billion years. However, from the mineral composition of the meteorite, Mikouchi and his team concluded that water probably existed much earlier, about 4.4 billion years ago.
"Igneous clasts, or fragmented rocks, in meteorites are formed from magma and are often caused by impact and oxidation," said Mikouchi. “This oxidation could have occurred if water was present on or in the Martian crust 4.4 billion years ago during an impact that melted part of the crust. Our analysis also suggests that such an impact would have released a lot of hydrogen, which would have contributed to the warming of the planet at a time when Mars already had a thick insulating atmosphere of carbon dioxide. "
If water existed on Mars earlier than thought, it suggests that water may be a natural by-product of a process that occurs early in planet formation. This finding could help researchers answer the question of where water comes from, which in turn could have implications for theories about the origins of life and the exploration of life beyond Earth.
Zhengbin Deng, Frédéric Moynier, Johan Villeneuve, Ninna K. Jensen, Deze Liu, Pierre Cartigny, Takashi Mikouchi, Julien Siebert, Arnaud Agranier, Marc Chaussidon, Martin Bizzarro. Early oxidation of the Martian crust triggered by impacts. Advances in science. DOI: 10.1126 / sciadv.abc4941
F.M. recognizes ERC under H2020 Framework / ERC Grant Agreement # 637503 (spotless). M.C. and F.M. Thanks to financial support from the UnivEarthS Labex program at the Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), the ANR CRADLE project (ANR-15-CE31-0004-1 ), the IPGP platform PARI and the Île-de-France region Sesam grant No. 12015908. MB recognizes funding from the Carlsberg Foundation (CF18_1105), the Danish National Research Foundation (DNRF97) and the European Research Council (ERC Advanced Grant Agreement 833275-DEEPTIME).
The University Museum of Tokyo University – http://www.um.u-tokyo.ac.jp/index_en.html