Completely uninformed speculation: * Provide more information to the search for habitable planets/extra-solar life * Better understand how the Earth's atmosph

Completely uninformed speculation: * Provide more information to the search for habitable planets/extra-solar life * Better understand how the Earth's atmosphere and overall ecosystem evolves over time, which may inform our understanding of long-term risks of climate change (and perhaps contribute to our ideas of how to manage terraforming on Earth, if we need to mitigate climate change).