“Who do you die for, question?”

The biggest themes in the sci-fi comedy Project Hail Mary are love and sacrifice. Cheesy? Not really. These, in fact, form the very heart of this human-alien buddy comedy from The Martian author Andy Weir.

From E.T. to Flight of the Navigator to Lilo & Stitch, Hollywood has long leaned on the alien-human friendship trope. In Phil Lord and Christopher Miller’s direction of Drew Goddard’s adapted screenplay, Project Hail Mary taps into that same emotional current, though with a more openly sentimental pull.

Also a survival tale, the film follows middle-school teacher Dr. Ryland Grace, a man who masks deep-seated loneliness and isolation, who is thrust into a spaceship and tasked with saving Earth. Head scientist-slash-government agent Eva Stratt (Sandra Hüller) turns to Grace’s expertise as a radical, exiled microbiologist and sends him on a suicide mission to a distant star to figure out what, exactly, is going wrong there.

The sun is dimming, slowly consumed by the fictional microorganism astrophage, which could plunge Earth into a catastrophic ice age within 30 years. Grace, a single and friendless man, is deemed the only one qualified for the interstellar journey.

It is in space, in the Tau Ceti star system, where Grace meets an alien that resembles a rock spider, whom he names Rocky. Together, the two race against time to save both their planets.

While far from the exhilarating, pitch-perfect The Martian (2015), Project Hail Mary is nevertheless an emotionally engaging watch. Perhaps its most tearful message is, again, “Who do you die for?” What matters to you so deeply that you would be willing to sacrifice your life for it, or for them?

At 2.36 hours, the film’s first half can feel plodding, opening with slapstick as Gosling stumbles, disoriented, through a spacecraft. The narrative frequently doubles back into flashbacks to fill in the backstory, but the tale and its dramatic stakes remain largely linear. As a result, the film sometimes lacks buildup and excitement, stretched thin by too much self-aware physical comedy and soundtrack, and dense scientific jargon.

Science and microbiology serve as instruments of survival here, which makes parts of the film fun, even if it also spends a lot of time on microscope work. Gosling, meanwhile, is fashioned into a nerdy but attractive savior figure, charming the audience with clumsiness even as he tries to save Earth and helps Rocky save his own world.

It is only when Grace meets Rocky that the film truly locks in. At first, the alien sounds emanating from this faceless spider-rock can feel generic, as though lifted from the same stock of alien noises heard in countless Hollywood films, but that quickly fades once the bond between the two takes hold. What follows is the connection between an emotionally traumatized, walled-up Grace and the bossy, boundary-less, easily attached Rocky.