Brad Pitt’s latest project has him thinking about male vulnerability.

In the sci-fi drama "Ad Astra," – which debuted on Thursday at the Venice Film Festival -- Pitt plays an astronaut whose dad, played by Tommy Lee Jones, vanishes during a mission. Decades later, Pitt’s character follows in his father's footsteps and, while on his mission, learns that not only is his father still alive, but that his survival has world-changing implications.

The film was "one of the most challenging films I've ever worked on," Pitt told Variety. In addition to the physical discomfort of having to be strapped into uncomfortable harnesses to simulate being in space, Pitt says the role made him feel emotionally vulnerable.

Speaking of director James Grey, Pitt said: “We've both grown up in an era where we were asked to be strong…and there is a value in that, but [also a] barrier because you’re hiding some of those things you feel ashamed of."

"We were asking the questions -- is there a better definition [of masculinity] for us…a better relationship with loved ones, with your kids and with ourselves?"

2019 is to be a big year for Pitt, who's already generating Oscar buzz for his work in the Quentin Tarantino movie "Once Upon a Time in Hollywood.” He's taking it in stride, however.

"Every year, I see amazing talent getting acknowledged, and amazing talent not getting acknowledged," he said. "When your name comes up, it's great, and when it doesn't, it's usually a friend [nominated], so I'm happy, too."