From Halopedia, the Halo wiki
This is Not Your Grave... (capitalized This Is Not Your Grave in Halo: The Master Chief Collection) is an Achievement in Halo: Reach and Halo: The Master Chief Collection.
In Halo: Reach the achievement is unlocked by completing the Campaign mission The Package on Normal, Heroic or Legendary.[1]
In Halo: The Master Chief Collection the achievement is unlocked by completing The Package on any difficulty. The Xbox achievement artwork is a Halo: Reach concept art of the Sabre Program Launch/Research Range facility at Farkas Lake.
The full concept art used for this achievement's art in Halo: The Master Chief Collection.