"The travelers went to the space station."
Translation:tengchaH lujaH lengwI'pu'.
When a verb includes a locative notion in itself, the way jaH does (its object is a location), using -Daq on the object is considered redundant, but not wrong. If you did it a lot Klingons would probably find it annoying. Hence tengchaH lujaH instead of tengchaHDaq lujaH.
The English sentence The travelers went to the space station sounds to my ear like it's describing a completed action: the trip is over; the travelers have arrived. The correct Klingon translation of this should be tengchaH lujaHpu' lengwI'pu' or tengchaH lujaHta' lengwI'pu' depending on whether you want to express the notion that the going was an action undertaken purposely. However, this course incorrectly assumes that Klingon perfective (-pu', -ta') equals English perfect tenses (have done, will have done, had done), and usually requires one to translate the other and vice versa. This is not correct Klingon.
Why not lujaHlI'? Because the action is not ongoing: -lI' means that the action is ongoing and has a known stopping point. That's not what's being described in this sentence.
No. Klingon does not mark past, present, or future tense with verb suffixes or other markers on verbs.
The suffix -lI' means in progress. lujaHlI' They were/are/will be going to it. -lI' implies there is an endpoint which the subject is making progress toward. This sentence can be interpreted as happening in the past, present, or future, depending on context.
The tricky part is that English requires progressive tenses, which look like but aren't the same as Klingon continuous aspects, when talking about actions that are "current" to the time context of the sentence. You can't say They went to the space station if you're trying to express their ongoing travel to that destination; you have to say They were going to the space station.
Klingon works differently: you don't have to use any kind of aspect marker at all to describe a current-in-the-context action. tengchaH lujaH is perfectly good for They are/were/will be going to the space station. It doesn't imply the ongoing state that the English MIGHT suggest; it's strictly a fact that at the time in question, the action of the subject is GO. Whether or not that action continues through time is not mentioned.
But Klingon lets you talk about ONGOING actions separately from bounded actions and states. tengchaH lujaHtaH They continue/continued/will continue going to the space station. tengchaH lujaHlI' They make/made/will make progress in going to the space station. Unlike the version with jaH, these talk about the action being ongoing.
Strictly speaking, The travelers went to the space station describes a completed action, and really should be translated with one of the Klingon forms of perfective. tengchaH lujaHpu' lengwI'pu' The travelers went to the space station. -pu' marks a verb that is completed, and as I say above you don't say went in English unless you mean it's completed (or if you mean something habitual or generic like The travelers went to the space station every month). Unfortunately, this course ignores this type of perfective English sentence and usually won't let you use -pu' where appropriate, so you usually won't be able to use -pu' here.
As David has pointed out, the -Daq is not incorrect, but perhaps not standard. We had not added it to the accepted translations, so I have now added it in.
Also, as pointed out by David, in this course we require some correspondence of the Klingon aspect markers to English complex tenses. Thus, in this course, lujaHlI' would be matched to "They were going to it."