Brad Pitt Focused and 'Low-Key' While Filming 'Ad Astra,' Kids Haven’t Visited Him On Set, Source Says
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Brad Pitt is in full work mode.

The 53-year-old actor continues to be low-key despite his A-list status as he films his latest movie, Ad Astra.

"When he’s not on set filming, he hangs out in his trailer,” a source tells ET. "He’s never late and he always arrives to set ready to work."

Despite his split from estranged wife Angelina Jolie, Pitt is looking better than ever and focused as production wraps in the next few weeks, the source adds. However, his six children -- Maddox, 16, Pax, 13, Zahara, 12, Shiloh, 11, and 9-year-old twins Knox and Vivienne -- have yet to visit him on set.

"Physically, he looks fantastic," the source says. "Brad is very friendly and genuine with everyone on set."

Directed by James Gray, Ad Astra follows Roy McBride (Pitt), an Army Corps engineer who goes on a journey across the galaxy in search of his father, a renegade scientist who went missing in space 20 years ago.

While Pitt has been keeping out of the public eye, Jolie has been busy promoting her Netflix filmFirst They Killed My Father. The Oscar winner has been traveling with her kids and taking them on red carpets for the movie's premieres. 

ET caught up with Jolie last month, where she gushed about her eldest son Maddox's work ethic. Hear what she had to say in the video below.