Writer-director James Gray’s first foray into science fiction has all the ponderousness of 2001: A Space Odyssey but none of its wonder. And I’m telling you this as a fan of Stanley Kubrick’s epic, and of space sagas generally — give me Inception, Gravity, Arrival, maybe The Martian, and I’m a happy astronaut.

But Ad Astra isn’t content with merely telling us a story on a system-wide canvas that stretches from Earth to Neptune. It also wants to constantly remind us of that fact, starting with the unnecessary opening credits that reveal that we’re in “the near future — a time of hope and conflict.” That pretty much sums up every SF story not set “a long time ago …”

Brad Pitt stars as Major Roy McBride, a second-generation spacefarer. His father, Clifford (Tommy Lee Jones), went to space decades earlier on something called the Lima Project,

which lost contact with Earth in the outer solar system. No one has ventured beyond Mars since.

Now a recent electrical storm (dubbed “the surge”) from that neck of the woods seems to be of human origin. Space Command wants Roy to send a message to his dad, telling him to knock it off. Roy thinks a personal visit would do the trick.

Roy’s hopscotch journey to the eighth planet from the sun requires a trip to Mars, which in this near future is only about three weeks away by spaceship, and home to about 1,000 hardy colonistsn.

Before that, he stops off at the moon, where competing claims from mining companies and pirates (space pirates!) have created a frontier atmosphere. But the car-chase-with-laser-guns scene there lacks both drama and excitement. I’d estimate it has only about one-sixth the gravity the director is going for.

Roy’s episodic journey also includes a rescue mission to a Norwegian science ship, where the movie almost turns into Alien.

Pitt brings a very different side of himself to the screen than as the happy-go-lucky stunt double in Quentin Tarantino’s Once Upon a Time … in Hollywood, but he does a good job creating what tension there is in the tale. And he’s really the film’s only star, what with his character’s father missing in action, his space chaperon (Donald Sutherland, ironically Jones’ buddy in the 2000 astro-comedy Space Cowboys) sidelined by an injury and his exwife (Liv Tyler) glimpsed only in the briefest of flashbacks.

With no one to talk to, Roy takes to narrating the action in voice-over, and occasionally sending soliloquies — part prayer, part meditation — to Space Command to prove his psychological well-being. Much is made of the fact that his pulse has never risen above 80, a reallife astronaut obsession since the dawn of the Space Age.

Gray shovels a lot of ideas into the mix, including the fatherson dynamic, the human need to tease out whether life exists somewhere off-world, and our sometimes incompatible desire to know the mind of God.

Jones’ character, in one of his last transmissions, suggests he may be grappling with both issues on the edge of the solar system.

But the film swings between being too specific — conversations that start, “Now, as you already know …” — and too vague, especially as to the exact nature of what befell Roy’s father. Is he really to blame for a storm that threatens to wipe out all life on Earth? And if so, how did he get his hands on that kind of power? And why — aside from narrative convenience — does Roy only find out bits and pieces of information as he goes along?

Ad Astra is a bold attempt to do something new with the genre, and that alone deserves applause. But its muddy storyline and limp plotting only prove how difficult it can be to weld big ideas to a rocket-science framework. A minor miscalculation is all it takes for your film to fail to reach orbit.