“He was a brother, he was an uncle, he was a father,” Kevin Costner, who plays NASA manager Al Harrison in the movie, told PEOPLE of Glenn on Saturday at a special screening of Hidden Figures in New York City.
“Then there’s the idea of how a man lived his life and I realized, that man, he lived his life. As a soldier, as an astronaut, as a senator. He was not only in control of the planes he flew. He was in control of his life.”
Glenn died on Thursday, surrounded by family at the Ohio State University Wexner Medical Center in Columbus, according to a hospital statement.
Glen Powell portrays the astronaut-turned-U.S. senator in the film about three African-American women who provided NASA with the key mathematical data used to get Glenn to space in the program’s first successful space mission.
He told PEOPLE that playing Glenn caused him to see the famed astronaut in a new light.
“I think the more you fall in love with him, the more you start to look at him like a grandfather that you’re really proud of,” he said at the screening.
“It really does feel like a loss. But at the end of the day, in 95 years, there’s not anybody I think has accomplished more in that amount of time,” Powell said.
He added: “[Glenn] affected so many people, inspired so many millions. It’s a loss. But at the same time, what a celebration of life.”
Jim Parsons, who plays Paul Stafford, said receiving the news of Glenn’s death while promoting such a movie was a “slap in the face.”
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“I would’ve been saddened and surprised no matter when the news came out,” Parsons told PEOPLE at the event. “But it’s a little ironic for him to pass away just within days of us doing all this stuff for this movie that’s introducing three new faces of the space movement that we’ve never known of before.”
He continued: “The beauty of it is that man, John Glenn, that man who just passed away, has, for our lifetime, been such the face — or at least a face — of NASA and the space movement. He was such an integral part of bringing someone like Katherine Johnson into the room.”
The movie is based on the novel of the same name by author Margot Lee Shetterly. The screenplay was co-written by Allison Schroeder and director Theodore Melfi.
Hidden Figures hits theaters Dec. 25.