https://www.polygon.com/2019/2/28/18244778/destiny-2-season-drifter-release-date-quest-thorn-gambit-prime-reckoning

Bungie just revealed Destiny 2: Season of the Drifter and released a development roadmap alongside it. The roadmap details the next 90 days of planned content for Destiny 2.

Starting on March 5, Annual Pass owners can try out the new modes: Gambit Prime — a more focused, class-based version of Gambit — and The Reckoning — a four player matchmade event like Court of Oryx or Blind Well. Three days later, The Reckoning’s second difficulty tier becomes available. Gambit Prime will only launch with one map — New Arcadia on Mars. A week later on March 12, Gambit Prime will get its second map — Deep Six on Titan.