|How to Start:||Talk to SAM|
After you complete the quest Comes Now the Power by acquiring a power regulator, install it in the Unreliable and head into orbit. Once done, find the disabled automaton SAM in a maintenance closet and examine it to start this quest. You can't get SAM up and running yet, but you can make some good progress. Talk to ADA to learn about SAM and Hawthorne's intentions for the janitorial bot, then head back up to your quarters and check the terminal, which will now have the entry [Search Term: SAM]. Select it to turn up three entries you can read, the third of which will mention an Acid Sweeper, which can be found on Roseway.
To advance this quest you'll need to get to Roseway, which can be done during the quest Passage to Anywhere. Just talk to Gladys and peruse the Stellar Bay Navkey, only to find out she wants a whopping 10,000 Bits for it. Fortunately she'll offer you a job which will earn you most of the Bits you'll need: investigate a distress signal coming from the supposedly abandoned Roseway settlement on Terra 2. This starts the quest The Distress Signal, and after getting ADA to playback the distress signal you'll be able to travel to Roseway.
Once on Roseway, continue to the actual town itself if you wish and talk to a scientist named Orson Shaw, who will give you the quest Vulcan's Hammer. This isn't technically necessary, but the quest will take you to a storage facility southeast of town, which is where you'll find the Acid Sweeper you need to get SAM up and running. Just head to the storage facility, enter via the eastern entrance (this will almost certainly require you to fight some marauders, their pet canids and a scrap automechanical) and from there head west until you reach a locked door [Lockpick 45]. Pick the lock and search some shelves near the floor in the middle of the room to find the Acid Sweeper you're after.
Now that you've got the part you need, just return to SAM on the Unreliable and pick the option "Install the acid steeper." to get SAM up and running.
As a companion, SAM is a bit of an oddity. He's got his own selection of perks just like normal companions (although he's got one fewer tier 2 perk than normal), but he cannot be equipped with new weapons and armor. Fortunately SAM's gear upgrades as his level increases, and his Armor and HP will almost always be considerably higher than that of your other companions. He also deals corrosion damage, which is strong against armor, automechanicals and mantisaurs, and not particularly weak to anything. In addition SAM has access to the Intimidate, Hack and Science skills... making him a somewhat more sturdy, if less personable, version of Max. Weird.