Unmanned space missions are able to explore the solar system in ways manned missions cannot. Equipped with scientific instruments such as telescopes, cameras, and spectrographs, robotic spacecraft are able to safely travel into space and radio back scientific data to researchers on Earth. In this interactive activity from NOVA, learn in greater detail how each of the Mars Exploration Rovers that arrived on the "Red Planet" in 2004 was equipped to determine, among other things, whether water ever existed there.
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