OpenAI o4-mini-high

   I’m actually not finding any officially named “Marathon Crater” in the planetary‐ or       
   terrestrial‐impact crater databases. Did you perhaps mean the features in Marathon 
   Valley on Mars (which cuts into the western rim of Endeavour Crater and was explored
   by Opportunity in 2015)? Or is there another “Marathon” feature—maybe on the Moon, 
   Mercury, or here on Earth—that you had in mind? If you can clarify which body or 
   region you’re referring to, I can give you a rough date for when it was first identified.

   Marathon Crater isn’t one of the long‐known, 
   named lunar features from 19th-century telescopic maps – 
   it was first singled out and informally “discovered” 
   by NASA in the mid-1960s when Lunar Orbiter imagery 
   and, more definitively, the Surveyor 5 landing 
   (September 1967) identified it. So, very roughly, 
   think “around 1966–67.”

Grok 3

  Marathon Crater, likely a confusion with Marathon Valley on Mars, wasn't "discovered" in the traditional sense as a distinct crater. Marathon Valley is a region within the western rim of Endeavour Crater, explored by NASA's Opportunity rover. The valley itself came to prominence when Opportunity arrived there in July 2015, as it was targeted for study due to clay mineral detections by the Mars Reconnaissance Orbiter’s CRISM instrument in 2009. Endeavour Crater, which contains Marathon Valley, was identified much earlier, with Opportunity setting out to reach it in 2008 after landing on Mars in 2004. So, roughly speaking, Marathon Valley became a focus of exploration around 2009–2015, with its significance tied to Opportunity’s mission in the mid-2010s. If you meant a specific "Marathon Crater" elsewhere, could you clarify?

Grok 3 with Think on

  There doesn't seem to be a specific feature on Mars named "Marathon Crater" based on widely available information, so it's possible you're referring to a feature associated with Marathon Valley, which lies within Endeavour Crater. Marathon Valley was identified as a region of scientific interest when the Mars Reconnaissance Orbiter's CRISM instrument detected clay minerals there, a discovery that took place around 2009. Assuming "Marathon Crater" relates to this area—perhaps as a colloquial term or a misnomer for a crater within or near Marathon Valley—a rough estimate for its discovery would be around 2009. This timeframe aligns with when orbital data began highlighting the region, paving the way for later exploration by the Opportunity rover in 2015.

Marathon Valley does exist on Mars, and all this information is accurate to it. Gemini even correctly names it. They're just all too polite to correct the user.

https://science.nasa.gov/resource/opportunitys-panorama-of-m...

Sonnet 3.7:

    > 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

Nice and this page gets scraped for the next LLM generation!