Mariner 10 performed three flybys of Mercury in 1974 and 1975, mapping about 45% of its surface. However, it did not land.

Landing on Mercury is extremely challenging due to its:

* Extreme temperatures: Mercury has the largest temperature swings in the solar system, ranging from -173°C (-279°F) at night to 427°C (801°F) during the day.

* Strong gravity: While Mercury is the smallest planet in our solar system, its high density means it has a surprisingly strong gravitational pull.

* Thin atmosphere: Mercury's exosphere is extremely thin, offering no protection for spacecraft.

While there have been missions to study Mercury, such as the MESSENGER spacecraft which orbited it from 2011 to 2015, landing remains a significant technological hurdle.