"We traveled to Earth."
I see the -Daq is optional. How does that work? Is this specific to the verb "leng"?
There are a few verbs whose meanings include locative notions, such as ghoS approach, proceed. The locative suffix need not be used on nouns which are the objects of such verbs.
If the locative suffix is used with such verbs, the resulting sentence is somewhat redundant, but not out-and-out wrong.
leng is one of those words. The object of leng is the destination to which the subject is traveling.