Life on Mars detection
The traditional approach to the life detection in Solar system emphasizes the chemical and microscopic markers. We suggest that it is macroscopic features of life that are the most promising markers. We further suggest that a particular stereo pair of images, obtained on Mars by MER Spirit on Sol 68, must be considered a proof of the life on Mars.
An effective technique is the key to the detection of life in Solar system and beyond. This must include an array of technologies, being applied in a proper combination, which fits the kind of access we have to the target environment, as well as the features of that environment. The traditional approach to the life detection in Solar system over emphasizes the chemical and microscopic markers .
CASE FOR MORPHOLOGICAL MACROSCOPIC BIOMARKERS
Life detection based solely on the microscopic and chemical biomarkers does not make much sense if life that is expected to be found, has any resemblance of life on Earth.
Consider the case of Mars. One can expect, that microbial life over there has sprung or was seeded possibly from Earth at the same roughly time as it has sprung on Earth.
An assumption that no macroscopic organisms has evolved from that life is quite ridiculous, considering what has happen on Earth, what abundance of creatures the natural selection have produced here.
There is only a slight chance even microscopic life was not ever present on Mars. It could also be true, that all life on Mars has become extinct due to changing conditions out there. Only under such hypotheses, taken with many more extra assumptions, it would make sense looking exclusively for the microscopic and chemical markers of life. In this case,
our intent would be to confirm absence of current life. So it would be then not a search for a life, but a search for the proof that no life is out there.
The problem here still is, that the life we are trying to disprove, is something unknown, and could be in unknown ways different from what we know as of now, about microscopic and chemical life markers.
The pure microscopic approach is destined to fail to prove negative at the end even if it is true, and is an awkward way to prove positive at the least. We can say, on other hand, that in most cases presence of mature microscopic life will be accompanied by the presence of macroscopic life. In case we are unable to detect macroscopic life on a planet, it is the most likely that no microscopic life is present either.
The conclusion is, that we must search for the macroscopic life when the goal is life detection on a planet.
This brings us to the question: what are the markers of macroscopic life?
Hooks, antennas, limbs, are some of the most prominent markers of the animal kingdom.
Hooks, leafs, branches, lianas, stems, flowers, berries are some of the most prominent markers of the plant kingdom.
The hooks, for example, never happen with the rocks and the rest of unanimated nature. One would expect them to be extremely reliable markers of life.
So, the Mars rover pictures must be looked at from the macroscopic biomarkers perspective. In this case, we actually were able to find pictures that fit the bill, the MER Spirit panoramic camera stereo pair, produced on Sol 68. The original JPG files 2P132402878EFF1800P2286R2M1.JPG and 2P132402878EFF1800P2286L2M1.JPG, can be can be found at .
The proper clips are presented as Fig.1 and Fig.2 below.
They focus on the special object, which has a hook at the closest to the camera end, with sharp point being directed away from the camera.
The shadow of hook on the ground is consistent with the light and the hook's shape.
Fig.1 Red-cyan color anaglyph.
Fig.2 Stereo pair clipped from the originals.
Obviously, if we are correct and the object in question proves presence of the macroscopic life on Mars, there must be other its products to discover. Many of them might be not as obvious cases as the ones with hooks represent, although.
1. Cady, S.L., Farmer, J.P., Grotzinger, J.P., Schopf, J.W., and Steele, A. (2003) Morphological biosignatures and the search for life on Mars. Astrobiology 3, 351–368.
2. NASA image gallery for Spirit, http://origin.mars5.jpl.nasa.gov/gallery/all/spirit.html