However, the 'correct' parse would be: "(Missions to and Sample Returns from) Nearby Interstellar Objects", i.e. the two nouns 'missions' and 'returns' (with 'sample' as its specifier) are linked by conjunction because only words of the the same type (noun, verb etc.) can by linked by conjunctions (or disjunctions, for that matter).
Missions (Plural Noun) To (Preposition) And (Conjunction) Sample (Verb)
Where they should have
Sample Returns (Compound Plural Noun)
My grammatical terms are probably all wrong, but you get the gist. It reads fine to me, but it can be hard to see these hiccups once you've read it the "correct" way. Edit: Also I think the unusually-placed preposition is pushing them that way.
So in expanded form:
"Missions to Nearby Interstellar Objects and Sample Returns from Nearby Interstellar Objects"
So "Collecting Samples from Nearby Interstellar Objects" would have been enough to do the job.
"Missions and Sample Returns to and from Nearby Interstellar Objects" is probably what I would have made from that, but no idea if that is allowed or comprehensible.
English is not my native tongue and I noticed that I don't understand capitalization as well as I thought. Why do you do that now? Just because it is a title? And why not for to/and/from? Are prepositions exempt?