Searching for the biological objects on Mars
A future rover, or an astronaut, charged among other tasks with search for life on Mars, must benefit from the today rover imagery .
The searcher, trained to visually recognize the candidate objects like those that can be observed and analyzed right now in the rover made pictures, will be much more efficient than if we were to pretend that life search has yet to be done totally from scratch.
Consequently, the detection of life candidate objects and images, development of methods of their analysis, of their concepts, and incorporation of results into the search for life program, should be a priority.
Let us consider some of the issues involved.
If in the process of object shape recognition, we were able to obtain at will the desired pictures and stereo pairs, we certainly could find out all that there is to know about that objectís shape.
However, in case of Martian imagery we have limited number of pictures of an object. How can we then be able to see what we see, namely the features that those images actually show?
One method geared towards that goal, is conversion of the stereo pairís information into 3D physical model, which then can be examined at will.
Computer program MARSOMETRY has been developed, which takes as input pixel coordinates of related to the object of interest identifiable points, and produces as output the orthogonal coordinates of those points, along with a map with those points shown. The algorithm used in the program, is consistent with PANCAM optical characteristics .
Before we take a look at actual model of the geometry of possible Martian plant, let us consider results for PANCAM calibration target .
Its geometry has been recovered from the stereo pair taken by the Spirit on Sol 16, 2P127783627EFF0327P2367L7M1/R1M1.
The precision obtained, apparently, should be sufficient for the shape recognition applications arising from MER PANCAM imagery.
Let us introduce now an interesting object photographed by Spirit on Sol 111, images 2P136234337EFF3600P2401L7M1/R1M1. Below are a red-cyan anaglyph made of the clipped from originals stereo pair , and a color rendition .
For the modeling we use 3 base plane points, 2 points for tracking stalk shadow, and 8 object surface points. Below are the map produced by MARSOMETRY, and a picture of the measurement model built. Modeling points located on the object surface, represented by the blue balls, stalk top and bottom by the red balls, and tip of stalk shadow by a green ball.
One has to conclude that general appearance of object, as seen in the anaglyph, is consistent with model.
It is possible to create concepts of this object, which would remain consistent with the model and object appearance. Here is one feasible example.
Although different, those concepts would have enough of features that are present both in the model and in the actual item - features that make this object a possible candidate for a Martian plant .
As always, deep gratitude goes to NASA for making this work and much more possible, by taking the magnificent pictures of Mars surface, and generously providing full public access to them.
1. NASA image gallery, http://origin.mars5.jpl.nasa.gov/gallery/all
2. Zeltsman, A. (2005) Visual Detection of life on Mars? Marsbugs, 12(20):2-3
3. Isenberg, H. (2004-2005) PanCam true color images from Spirit and Opportunity Mars Exploration Rovers,
4. Bell III J. F. et al.† (2003) The Mars Exploration Rover Athena Panoramic Camera (Pancam) Investigation, J. Geophys. Res., Special issue on the Mars Exploration Rover mission, 73,83