Early Life on Mars Might Have Wiped Out Life on Mars

Even though Mars and Earth had similar early histories, including water, Mars still ended up with fewer minerals than Earth. Why? Image Credit: ESO/M. Kornmesser
Even though Mars and Earth had similar early histories, including water, Mars still ended up with fewer minerals than Earth. Why? Image Credit: ESO/M. Kornmesser

Life might have wiped itself out on early Mars. That’s not as absurd as it sounds; that’s sort of what happened on Earth.

But life on Earth evolved and persisted, while on Mars, it didn’t.

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Did Ancient Martian Life Eat Rocks For Food?

Some lucky astronomers get to work with some of the rarest material in the world.  Real Martian meteorites are extraordinarily rare, but are invaluable in terms of understanding Martian geology. Now, one of the most famous meteorites, nicknamed “Black Beauty”, is helping shed light on a much more speculative area of science: Martian biology.

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Since Perseverance is Searching for Life, What Will it Be Looking for?

The rocks seen here along the shoreline of Lake Salda in Turkey were formed over time by microbes that trap minerals and sediments in the water. These so-called microbialites were once a major form of life on Earth and provide some of the oldest known fossilized records of life on our planet. NASA's Mars 2020 Perseverance mission will search for signs of ancient life on the Martian surface. Studying these microbial fossils on Earth has helped scientists prepare for the mission. Image Credit: NASA/JPL-Caltech

You have to be careful what you say to people. When NASA or someone else says that the Perseverance rover will be looking for fossil evidence of ancient life, the uninformed may guffaw loudly. Or worse, they may think that scientists are looking for actual animal skeletons or something.

Of course, that’s not the case.

So what is Perseverance looking for?

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There’s Evidence That Mars Once Had an Atmosphere With Less Oxygen. A Possible Biosignature For Life?

Remote sensing is only useful if scientists have an idea of what they are looking at.  That knowledge is especially important for remote sensing applications on other planets, such as Mars, where it is extraordinarily difficult to collect information about an observed object in any other way.  To make up for the lack of ability to perform other tests in situ, scientists set up laboratory experiments with different environments and materials and compare the remote sensing data with the observed remote objects. 

That is exactly what Jiacheng Liu, a doctoral student at the University of Hong Kong, did with remote sensing data from the surface of Mars.  What he found gave new weight to a novel theory – that Mars didn’t used to have a significant amount of oxygen in its atmosphere.  The fact that it does now prompts the question of where all the oxygen that exists in the atmosphere today came from.  One possible answer is the same place it came from on Earth – photosynthetic life.

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