Howabout Gundam? Angsty teen/preteen protagonist trope can get annoying, but I'd classify a lot of UC Gundam as pretty "hard" SF. Granted there are some deus ex machina type elements to it (psychic newtypes, Minovsky particles, etc.).
Planetes, on the other hand, isn't much like either of these. Its subject matter is intensely personal, and even when the characters occasionally get involved in high-stakes situations, it's less to do with changes in society (which occur much more slowly) and more to do with someone turning their small-scale private difficulties into everybody else's problem. The political elements intrude for a while and disappear again, and I don't remember them nearly as well as the bits about a lost watch, or a marriage proposal.
In a nutshell, if Gundam and The Expanse need magic because they're larger-than-life, Planetes has no use for it, because it's exactly-the-same-size-as-life.
But Planetes is on a different level, with accurate depictions of orbital dynamics and spacer life.