NOW YOU SEE IT – NOW YOU DON'T: COMPARING TEXTURAL DETAILS VISIBLE WITH THE HAND LENS IMAGERS OF THE MER ROVERS AND MARS SCIENCE LAB

The microscopic imagers (MI) on the current Mars rovers (MER) are an extremely useful tool for the characterization of Mars surface rocks. A number of scientific insights that came out of the MER mission would have been much more tenuous, or even impossible to attain without the ability to examine grains and pore spaces of rocks and soils at high resolution. At a nominal resolution of 30 microns per pixel these devices allow the recognition of particles as small as fine sand. This level of resolution can be met or exceeded by today's consumer grade digital cameras.

Material from the gypsum dunes and playa of White Sands National Monument, New Mexico, was photographed with a 4 megapixel consumer camera, a photo binocular scope, and by scanning electron microscope. At the consumer camera level, 30 micron per pixel resolution shows and resolves details such as microbial mat laminae, binding of grains in desert crust, grain type differences, mm-scale laminae, and moisture induced grain clumping. Details of mm-size grains, however, are lost due to heavy pixelation. Grain surface details and pore space objects are not resolvable, and grain margins are quite fuzzy. Simulating the 12.5 microns per pixel resolution of the hand lens imager (MAHLI) on Mars Science Lab (MSL) with the help of a binocular microscope shows that this undramatic (30 to 12.5 microns per pixel) increase in resolution should allow us to see aforementioned details, as well as features due to grain corrosion/dissolution and meniscal cement formation. The latter are critical observations regarding the past presence of liquid water.

Nonetheless, a lens system attached to a digital sensor chip (CCD) still falls far short of the resolving power of the union between human eye and a standard hand lens. For example, even at the improved resolution level (12.5 microns per pixel) of the MSL MAHLI imager, one can not resolve the filaments in a microbial mat. It is possible to see these, however, if the same lens system is placed in front of a human eye.