Missions can be accessed through the NPC traders scattered around the map. Open your map by pressing "M" and look for these markers to indicate where there is a trader nearby. Access the trader and click on "talk" to see a list of activities possible through that trader.
Equals a Protected Trader.
Equals a Trader that has lived at least one restart. "Not Safe"
Equals a Trader that was killed and respawned.
Equals a Dead Trader or another targets (minerals,ferris,containers...).