Look again at this dot. That’s not here. That’s not home. That’s certainly not us. The quest for water on planet Mars has become one of the most well known goals in space exploration, but it seems that perhaps we’re looking in the wrong place – not in space, but in time. A couple of billion years ago, Mars may have been a lot more similar to Earth.
After all, Earth and Mars formed from the same stuff. While the two worlds have different histories which have led to they way they are today, they would have had a very similar start in life. The latest hint at a watery history on Mars has come from a rather unassuming source. A small rock found in Morocco. This rock, NWA 7034 (nicknamed “black beauty”), is actually a meteorite – one which originated not on Earth but on Mars. Finding a 320g stone which was once blasted off the surface of another planet is remarkable enough, but this one is particularly unusual. While it bears some similarity to the other 100 or so Mars rocks found here on Earth, in many ways it’s very different. Both in appearance and in elemental composition, this rock is a very different beast.
The most remarkable thing about black beauty is its high water content. It contains almost 6000 parts per million of water. While that may not sound like an awful lot, it’s ten times as much as found in any similar martian stones. Simply, there was much more water around when this rock was formed, and the reason could be its age. At around 2 billion years old, it’s at least 4 times older than any of the other known meteorites. The implication is that Mars was once a much wetter world than it is today.
Excitingly, this means there could well have been a chance that Mars was once a home to life. Here on Earth, the most ancient known fossils are 3.49 billion years old, and it’s likely that life may have existed prior to even that. While it’s been less than a billion years since multicellular life evolved here on Earth, evidence has been found of complex life on Earth up to 2.7 billion years old. If life on Earth is that old, there may have been ample time for some form of complex life to have evolved on Mars too. That is, before our planetary neighbour became a barren desert world.
But what happened? What killed Mars? How did it turn into the parched and dusty little world we see today? To be honest, no one really knows for sure. There are a few hints of ancient catastrophes. Secrets hidden in the crust of our planet’s butterscotchy brother. But that’s a story for another day…
The research paper on meteorite NWA 7034 has been published in Science, if you have access and would like to read the deliciously technical details!