"What is the goal of the research?" should be accepted, shouldn't it?
What is the intention of the research? should be acceptable
Purpose and intention are two different things.
DL's hints are deceptive. I think that proposito has to do with "de proposito" meaning "intentionally".
Besides that expression, "propósito" is perfect here.
Can following nouns: "motivo, objetivo, razão" be used instead of propósito here?
Surely objective and purpose is the same!?