Mars had oxygen before Earth
Oxygen existed on Mars 4 billion years ago, 1.5 billion years earlier than on Earth, American scientists have confirmed.
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Oxygen existed in the Martian atmosphere about 4 billion years ago. |
Scientists from the US National Aeronautics and Space Administration (NASA) compared meteorites that had fallen to Earth from Mars with data from rocks collected by the Spirit Mars rover on Mars. They found major differences in the chemical composition of the two groups of rocks. These differences were caused by the presence of oxygen in the Martian atmosphere.
The Martian rocks analyzed by Spirit Mars are 3.7 billion years old. Analysis shows that they were exposed to oxygen before they sank into the Earth. In contrast, Martian meteorites on Earth were buried in the Earth before being ejected by volcanic eruptions and then crashed into the Earth. Because they were buried in the Earth, they were not exposed to oxygen.
The new discovery is welcome news for those who believe that life once existed on Mars. On Earth, oxygen gradually appeared in the atmosphere thanks to bacteria capable of photosynthesis (using light to create nutrients and releasing oxygen). However, researchers are not sure if a similar mechanism was at work on Mars. They speculate that oxygen may have been created by photosynthetic bacteria or by some chemical reaction in the atmosphere.
"Mars had an oxygen-rich atmosphere about 4 billion years ago, long before oxygen appeared on Earth about 2.5 billion years ago. It is very likely that Mars was a wet, warm planet before oxygen made up a large proportion of the Earth's atmosphere," said Professor Bernard Wood, a researcher at the University of Oxford in the UK. He is the leader of the Martian atmosphere research team.
The study by Wood and colleagues is published in the journal Nature.
According to VnExpress - VT
