Mars Had an Oxygen-Rich Atmosphere Four Billion Years Ago
Mars had an oxygen-rich atmosphere more than a billion years before the Earth, say scientists. An examination of meteorites and rocks on the planet suggests that oxygen was affecting the Martian surface four billion years ago.
On Earth, oxygen did not build up to appreciable quantities in the atmosphere for at least another 1.5bn years.
The researchers compared Martian meteorites that have crashed onto the Earth with data from rocks examined by Nasa’s Spirit Mars rover. Differences in their composition can best be explained by an abundance of oxygen early in Martian history.