The Means to an End quest is the second quest you will get during the early portion of Season of Arrivals. To access it, you will need to finish up the In The Face of Darkness quest that you initially do for the Drifter.
When you rescue Eris Morn after first logging in, you will need to visit the Drifter who will send you to Io to take part in the new Contact public event. Play through all the event then return to Drifter. All you need to do is follow the very easy quest steps. Drifter will tell you to use the Decoder that is located to the left of his plinth, then you will need to fire up the Prismatic Recaster on the wall to the left. It is all very easy, step by step stuff, so there should be no struggle here.
Once this quest is done, the game should automatically give you the Means to an End quest. Unfortunately, many people out there seem to be running into issues here, and the game is not populating the quest for them. Because the start of the Means to and End quest is supposed to be trigger by the end of In the Face of Darkness, there really isn’t much you can do here.
It sucks, but you will just need to wait until Bungie resolves whatever issues might be interfering in the quest populating for some of the player base. Means to an End is actually a pretty long quest, with multiple steps, and other players are reporting issues with the quest breaking at some of the steps as well, so keep that in mind as you play through it.