Mars Yamato Meteorite: Odd 'Tunnels' & 'Spheres' and Ancient Martian Life

This scanning electron microscope image shows spheroidal features in a layer of iddingsite, a mineral formed by action of water, in the meteorite Yamato 000593 that came from Mars. 

An area with the spheres, circled in red, was found to have about twice as much carbon present as an area (circled in blue) without the spheres.

Credit: NASA

The discovery of tiny carbon-rich balls and tunnels inside a Martian meteorite has once again raised the possibility that the Red Planet was teeming with primitive life millions of years ago.

The meteorite, which fell to Earth during the Stone Age, contains microscopic burrows and spheres that resemble the marks microorganisms leave when they eat through rocks on Earth, scientists report in the journal Astrobiology this month.

What's more, these features seem to have been pressed into the Mars rock before it was hurled off the Red Planet by an impact event, the researchers add.

White Lauren M., Gibson Everett K., Thomas-Keprta Kathie L., Clemett Simon J., and McKay David S.; The authors of the new research are not claiming they've found evidence of ancient life on Mars.

In fact, nowhere in their paper do they use the word "life." (Their preferred term is "biotic activity.")

But their findings revive the debate about the possibility of microbes in Mars' past and highlight how much information scientists can actually glean from Martian meteorites that end up on Earth.

"It further strengthens the case for past life on Mars, but, of course, it is by no means proof," said astrobiologist Dirk Schulze-Makuch of Washington State University, who was not involved in the study.

Scientists haven't yet found any solid proof that life actually existed on ancient Mars — but they have found evidence that the planet could have been habitable.

Though Mars is barren today, scientists think water — a key ingredient for life — would have covered its surface in the form of oceans, rivers and streams.

And last year, NASA's newest Mars rover, Curiosity, discovered the first evidence that the Red Planet could have supported living microbes billions of years ago.

While Mars rovers, landers and satellites are hunting for life-friendly conditions on the Red Planet, scientists also can look for evidence of ancient life in Martian meteorites that have landed on Earth.

This scanning electron microscope image of a polished thin section of a meteorite from Mars shows tunnels and curved microtunnels. 

The clay mineral iddingsite is present in this meteorite, named Yamato 000593, which was found in Antarctica in 2000 and identified as originating from Mars. 

The scale bar at lower left is 2 microns. 

Credit: NASA