Scientists have confirmed that a meteorite seen to fall in Morocco, July 2011 came from Mars! The meteorite has been called Tissint after the village near where it was found.
Most meteorites are “finds” rather than “falls” (seen falling) and very few come from Mars so this is exciting news. The last Martian “fall” was in 1962. Tissint will hopefully provide new clues about the geology and chemical conditions on the Red Planet.
As Tissint was not on the ground for long before it was collected (less than 6 months) it won’t have been exposed to much terrestrial contamination and any organic matter it contains will have been preserved and could help answer the big questions we have such as “was there life on Mars?” or “is Mars habitable?”. However, the chances of finding organic matter in Tissint are thought to be very small (and biological matter even more unlikely) as it is an igneous rock and signs of life are more likely to be found in sedimentary rocks but these would not survive the journey to Earth. So to really learn more about the Red Planet and answer these “big questions” we need to bring samples back from Mars ourselves in a sample-return mission!
Thousands of meteorites have been found on Earth but the majority come from asteroids and fewer than 40 are believed to be from Mars. We are quite confident that these meteorites came from Mars because:
- they are younger than asteroidal meteorites suggesting they formed on a large, geologically active planet.
- they contain mineral compositions that point towards formation on a large planet.
- they are unlikely to come from Venus as it has a thick atmosphere which would prevent most material being ejected into space.
- they are unlikely to come from Jupiter’s moons as they wouldn’t be able to escape the gravity of Jupiter.
- the composition of gases found trapped inside some of them is identical within error to the composition of the Martian atmosphere measured by the Viking landers.
Tissint has been confirmed as Martian by matching its oxygen isotope signature to meteorites already known to be Martian.
More details about Tissint are available at the Meteoritical Society Database here.