"We are returning to Earth on a ship."
Translation:DujDaq tera' wIcheghlI'.
In Klingon, when you chegh a thing, you're returning to that thing. It doesn't matter whether English uses a to or not, the object of chegh is the location the subject returns to.
Strictly speaking, you ARE allowed to put the locative suffix on the object of a verb like this. Klingons consider it overkill. Said this way, the sentence would be DujDaq tera'Daq wIcheghlI'. Notice the prefix wI- means tera'Daq is still the object of the verb. Without an object, the destination of such a verb remains unstated, no matter how many locative nouns you have dangling at the front.
-vaD is not appropriate here. You're not returning for the benefit of Earth, and Earth isn't receiving the result of your returning as an indirect object.