> tell me about the marathon crater

    I'd be happy to tell you about Marathon Crater. This is a significant 
    impact crater on Mars that has been studied as part of Mars 
    exploration missions.

    Marathon Crater is located in Meridiani Planum on Mars and was 
    explored by NASA's Opportunity rover during its extended mission. 
    The crater is named after Marathon, a town in Texas, following 
    the naming convention of using Earth locations for features in 
    Meridiani Planum.... etc etc