I would say Ad Astra is filled to the brim with fantastic and implausible elements. The visual design is very realistic, and this contrast adds to the movie's sense of disconnect (which is great it you like it, and a movie killer if you don't).
If we are talking at implausibility, Gravity is filled to the brim with it. It does a very lousy presentation of orbital mechanic: you don't point at a general direction of space station which is 70km away, give an impulse away from it and slowly drift to it. It is not how it works!
On top of this implausibility, the criteria in the parent post was ‘there’s no “supernatural” element whatsoever,’ which given the heroic ghost of Kowalski‘s role in saving the protagonist (as a “hallucination”), should also rule it out. Never mind that the film was essentially disorienting scenes and
Sandra Bullock repeatedly shouting into the cameras
Hallucinations aren’t supernatural. Kowalski wasn’t a ghost. This was evident in the movie.
The Martian’s bad physics and chemistry should also rule it out from the list based on your criteria. Which would be sad, because despite that, it’s a great movie and book.
Book chemistry and physics (other than dust storm) looks rather plausible, what didn't you like there? Movie added some ridiculous stuff when flying with punctured space suit, that was pathetic.
Objects in space in adjacent orbits around aren't floating in space, they are falling on Earth at a great speed. If you apply an impulse in the way as shown in the movie, you'll expand or shrink the orbit excentricity and you will likely start moving up or down rapidly relative to your target, instead of closing in. This way to get to your target you'll need to burn an insane amount of fuel and do orbit corrections every second. The right way is to make one impulse to change your orbit in such a way that your new orbit will intersect the orbit of your target (and that you both will be there at the same time), and the direction of such impulse might be far from obvious. More likely one impulse will result in a very long transit orbit, so a better course would be two or more orbital corrections.
So is The Martian. The physics in the movie and book are absolutely magical: windstorms powerful enough to impale people but not enough air pressure to require a top to the spacecraft. Toxic, perchlorate soil growing potatoes… Both the book and movie are wonderful, but have huge gaps of implausibility.
Ad Astra is "story" wrapped around visual effects to allow Brad Pitt be used as lead actor. And there could be so much to it: The emotional controls, done by I assume AI? Great plot for a dystopian society. A rogue scientist at the edge of explored space posing a big threat? The Heart of Darkness is great, regardless of version. Various powers battling of the few rocks in what is otherwise an empty solar system? The Expense shows us how great that can be.
All of that in one film? Not so much. And then there a the logic holes bigger than a smaller galaxy. Earth is facing severe energy issues, up to the point a habdfull of dudes are fighting over three luna rovers? Could be fun, ubtil one realizes that there is apparebtly enough energy to be had to kill civilisation by energy waves created somewhere around Saturn... Then Brad is sent on a secret missions, and instead of flying on a military vessel to the lunar station, he takes acivilian flight wearing uniform. Only to land travle across the moon. The inly reason for that seems to be show some fancy lunar battle scene... I could go on...
Space Cowboys so, that would fit. As would Alien and Aliens, everything after Prometeus... If I want Eric Daenicken, I go read one of his books.
