Tracking down lost ghost locations in Destiny 2's The Final Shape expansion might not seem like the highest priority when the Witness is set to rewrite all of creation, but doing so will complete the Spirit Guide seasonal triumph, plus get you some coveted red-border destination weapons for the trouble.
You won't unlock these mini-quests until you finish the main campaign and start the Ergo Sum exotic quest that appears immediately after. You can also only recover one ghost at a time, so you won't be able to do that seasonal challenge straight away. Still, these quests do give out a lot of red border destination weapons, and doing the initial missions will unlock the exotic weapon quest Convalescence: Budding, which gets you the kinetic heavy trace rifle, Microcosm.
