The Microscopic Imager on the Spirit and Opportunity Rovers of the Mars Exploration Rovers is also known as MI. The high-resolution camera gives magnifying glass-views of Martian rocks and soils. It scouts promising targets for detailed study and analysis by other instruments on the rover.
The Microscopic Imager (MI) instrument
MI Info

Tech Specs

  • MAIN JOB:To provide extreme close-up black-and-white views of rocks and soils, providing context for the interpretation of data about minerals and elements.

  • LOCATION:Mounted on the turret at the end of the robotic arm.

  • MASS:~7.5 ounces (210 grams); 10.2 ounces (290 grams) including the dust cover and contact sensor

  • POWER:2.5-4.3 Watts for camera; 0.5 Watt for dust cover open or close

  • SIZE:1.91 inches (48.6 millimeters high), 2 inches (51 millimeters) long and 1.61 inches (41 millimeters) wide.

  • COLOR QUALITY:Single broad-band filter, so imaging is monochromatic (black and white)

  • IMAGE SIZE:1024 x 1024 pixels

  • IMAGE RESOLUTION:31 microns per pixel (0.001 inch or 0.031 millimeter per pixel). Able to resolve 0.004-inch (0.1 millimeter) objects/features.

  • FOCAL LENGTH:0.8 inch (21 millimeters), with optimal focus distance of 2.67 inches (68 millimeters)

  • FOCAL RATIO AND FIELD OF VIEW:f/15, yielding an IFOV of 30 +/- 1.5 micrometers per pixel on-axis

Ken Herkenhoff
Microscopic Imager Payload Element Lead
United States Geological Survey
Flagstaff, Arizona

The Microscopic Imager

The Microscopic Imager is a combination of a microscope and a CCD camera that provides information on the small-scale features of martian rocks and soils. It complements the findings of other science instruments by producing close-up views of surface materials. Some of those materials are in their natural state, while others may be views of fresh surfaces exposed by the Rock Abrasion Tool.

Image taken by the Microscopic Imager
Image taken by the Microscopic Imager
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Microscopic imaging is used to analyze the size and shape of grains in sedimentary rocks, which is important for identifying whether water may have existed in the planet's past.

The Microscopic Imager is located on the arm of the rover. Its field of view is 1024 x 1024 pixels in size and it has a single, broad-band filter so imaging is in black and white.