First off, it must be noted that while Spirit hasn't transmitted any messages since 2010, Opportunity was still clocking in work hours from Mars and sending information back to Earth in 2011. In fact, like any earthling, Opportunity scouts places to hole up for the winter in order to get the most solar energy stored in its batteries.
Spirit and Opportunity
Spirit and Opportunity, it turns out, aren't just words we use to make ourselves feel better when we're depressed. In 2003, NASA launched the cheerfully named Spirit and Opportunity rovers, which embarked on a mission of far greater mobility and distance than Pathfinder.
Both the rovers share a few noteworthy features. They can both generate power from solar panels and store it in internal batteries. Just in case any little green men are nearby, the rovers can take high-resolution color images or bust out magnifying cameras for Earthbound scientists to scrutinize objects. Multiple spectrometers on the arm of the rovers employ all sorts of tricks to determine the composition of rocks, including tracking how much heat an object is giving off and firing alpha particles at it. Spirit and Opportunity also were equipped with an installed drill (Rock Abrasion Tool) to bore into the planet's surface.
The body of the rover is called the warm electronic box (WEB). An equipment deck sits on top of the rover, where the mast (or periscope eye) and cameras reside. The gold-painted walls of the rover's body are designed to withstand minus140 degrees F (minus 96 degrees C) temperatures. Inside the WEB of the rover are lithium ion batteries, radios and electronic things like spectrometers, all requiring warmth to function. The brain of the rover is a computer that's comparable to a high-end, powerful laptop but with special memory functions that won't destruct with radiation and shut-offs. The computers also continually check temperatures to ensure a "healthy" rover.
What Spirit and Opportunity found was a credit to the technology that allowed them to explore Mars. Within a couple months of landing, the Opportunity uncovered evidence of saltwater, which leaves open the possibility that life (and fossil indications) might at one time have existed on the planet. Spirit stumbled across rocks that pointed to an earlier, unrulier Mars that was marked by impacts, explosive volcanism and subsurface water [source: NASA Mars].
We're going to learn about some features and explorations of more recent rovers, but first let's slowly traverse to the next page and look at some of the equipment and science that Spirit and Opportunity have.