I find it fascinating that this Martian meteorite issue won’t die. It is well-known that it is sheer will alone that assures that the creature we call the Lich will get up again tomorrow evening, but that doesn’t seem to be what is going on here.
Dr. Martin Fisk, a professor of marine geology in the College of Oceanic and Atmospheric Sciences at Oregon State University and his colleagues published a paper in the February 2006 issue of the journal Astrobiology.
Another summary of their findings can be read here.
From what I understand, they have studied the weathering patterns in iron-magnesium silicate minerals Olivine and Pyroxene in Earth mantle rocks. It is now well-known that Earth rocks are teaming with iron and magnesium consuming bacteria down to great depths on the order of miles. Fisk and colleagues found that bioweathering does occur in these minerals on Earth due to interactions between clay mineral by-products and nucleic acids. They have also examined meteorites that are known to have been blasted off the surface of Mars. In the meteorite called Nakhla (found in Egypt), they found some olivines and pyroxenes to possess weathering patterns similar in size and shape to those found in Earth rocks. This meteorite is believed to have exposed to water while on Mars which lead to the formation of the clay minerals. If bacteria existed in the water on Mars, they could have been responsible for the weathering patterns that are similar to those seen in Earth rocks. Note that this is NOT proof that bacteria have existed on Mars, but rather is yet another intriguing piece of a puzzle still under construction.
Now the Nakhla meteorite is not the same meteorite that you are likely to have heard of previously in connection with Martian microbes. The other meteorite is ALH84001, which was found in the Allen Hills of Antarctica in 1984. Here is a detailed description of the Science paper findings related to ALH84001.
Aside from the photos of bacteria-shaped fossils, there was additional evidence. First there was the presence of polycyclic aromatic hydrocarbons at the sites of the presumed fossils, and second there was the presence of magnetite, which on Earth are made only by bacteria: details, and more details. However, this paper (which I have not thoroughly read), claims that the magnetite is consistent with in situ growth via diffusion in special situations.
By this time the scientific community had pretty much written off the meteorite since what looked to be fossil bacteria were 10 times too small. The thinking was that they were too small to host the chemical machinery believed to be needed for life. However, recently nanobacteria have been discovered deep in Earth rocks (and fossilized too) by Dr. Philippa Uwins. The belief is that nanobacteria may actually be the dominant life form on Earth…and more here.
Do nanobacteria rule Earth and Mars?
Note that this is slightly different from the controversy surrounding the suggestion by Finnish scientists that nanobacteria are responsible for calcium deposits in our teeth, kidney stones, and arterial plaque.
Sometime in the near future I will blog about Panspermia, the transfer of life from world to world.