Shiphand: The Steady Traveler is a Dominion shiphand mission. It is obtained in Deradune by speaking with Captain Milo in Endless Vigil.
You met Captain Milo on the outskirts of Endless Vigil in Deradune. The hapless captain is in a bind, for his asteroid mining settlement, M-13, has been infested by strange aliens.
What kind of aliens?
Strange, parasitical creatures. I haven't seen them myself, but if the distress calls are any indication, they're quite frightful.