Scientists analyzed a meteorite found in the Sahara Desert in 2012. The meteorite comes from Mars and is called NWA 7533. Scientists have been studying the meteorite to see its composition and what Mars might have looked like 4.4 billion years ago. The mineral composition of meteorites reveals chemical signals of oxidation that occur as water forms. The meteorite, which is very small and weighs only 84 grams, was found in northwest Africa, and NWA 7533 is the remains of a larger meteorite that broke apart as it entered the Earth’s atmosphere.
The meteorite was previously measured to be 4.4 billion years old, so researchers can now overturn the previous theory that Mars had water for at least 3.7 billion years. Meteorites show that water appeared on the Red Planet 700,000 years ago, meaning it appeared on Mars much earlier than previously thought. There are indications that water is a natural by-product of a process in the early days of planetary formation. Scientists hope the discovery will help answer the lingering question of where water comes from. NWA 7533 is the oldest surviving Martian meteorite.
The researchers performed four different spectral analyses of meteorite samples. Each is a method of detecting chemical fingerprints, and there is strong evidence that magma is oxidized. Oxidation could have occurred if water had been in the Martian crust 4.4 billion years ago, melting part of the crust in an impact. The analysis also showed that impacts that produced meteorites released large amounts of hydrogen, which helped the planets warm up when Mars already had a thick atmosphere. Now, the Martian atmosphere has disappeared.