https://www.polygon.com/2017/9/8/16274074/destiny-2-dlc-curse-of-osiris-expansion-leak-mercury

The first expansion for Destiny 2 is called Curse of Osiris and will focus on the titular Warlock who gave his name to Destiny’s most intense competitive multiplayer event, according to a product description leaked on the Xbox Store.

Curse of Osiris will introduce a new playable planet, Mercury, with a zone called the Infinite Forest. This will be the first time that players have been able to explore the closest planet to the sun in story missions or open-world activities. So far, Mercury has only been playable as the setting for the Lighthouse, a social space in the original Destiny, and for four Crucible maps across both games.