Mars meteorite: contact with liquid water only 742 million years ago
A rock carved out of Mars 11 million years ago contains traces of liquid water. This has measurably changed its composition.
The Lafayette meteorite
(Image: Purdue Brand Studio)
A meteorite from Mars came into contact with liquid water on the Red Planet 742 million years ago. This was discovered by a research team led by planetologist Marissa Tremblay from Purdue University in the USA. The date is significantly later than previous estimates of the presence of liquid water on Mars. However, the research group believes that contact took place below the surface and with only temporarily melted permafrost ice. The process responsible is probably still taking place today.
Disappeared in a drawer after discovery
The traces were discovered in the so-called Lafayette meteorite, writes the group. It is so named because it was found in a drawer at the university in 1931, which is located in the city of West Lafayette in the US state of Indiana. It is not known when it was found. Its examination had already revealed that it was ejected from Mars 11 million years ago during an asteroid impact. Due to its unusual discovery history, it is not known exactly when it hit the Earth, but an analysis of organic contamination two years ago revealed 1919 as the most likely date.
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The research team determined when the rock on Mars came into contact with liquid water on the basis of minerals that were formed in the process. These do not indicate that there was plenty of liquid water there at the time, hence the hypothesis of contact below the surface. The group also writes that they were able to show that neither the 11 million years in space nor the decades on Earth had falsified the age determination. The method used could now also be applied to other meteorites in order to search for traces of liquid water. The research work has now been published in Geochemical Perspective Letters.
(mho)
