diagram of Mars Exploration Rover

This diagram shows all of the gizmos and gadgets that Spirit and Opportunity came equipped with.

Image courtesy NASA

What Goes Into and Onto the Rover

Just saying that Spirit and Opportunity have cameras and some fancy radio equipment really doesn't cut it. At 384 pounds (170 kilograms) each -- and a total of $850 million to build -- you better believe the equipment is not just your trusty MacBook, superglued to an AM/FM radio.

First of all, a panoramic camera is mounted on each rover to provide a larger geologic context. Located on the mast about 5 feet (1.5 meters) off the ground, the camera doesn't just snap color images but carries 14 different filters that can identify rock and soil targets for closer looks.

A miniature thermal emission spectrometer identifies minerals at the site with a little help from infrared wavelengths. It's used to find distinctive patterns that could show water movement. On the rover arm is a Moessbauer Spectrometer, which is placed directly on samples to find iron-bearing minerals, another tool to help determine how water has affected the soil and rock.

To determine the composition of rocks, an Alpha Particle X-ray Spectrometer is used -- the same kind found in geology labs, which helps scientists determine origins and changes in the samples. The microscopic imaging tool can carefully investigate rock formation and variations.