400 Days is a 2015 American science fiction film written and directed by Matt Osterman and starring Brandon Routh, Caity Lotz, Ben Feldman, and Dane Cook (also serving as executive producer) as astronauts sent on a 400-day-long simulated mission to a distant planet, to test the psychological effects of deep space travel.

Four astronauts – Captain Theo Cooper, Dr. Emily McTier, Bug Kieslowski, and Cole Dvorak – begin a 400-day-long simulation on Earth intended to study the long-term effects of space travel.

After his escape, the crew decides to exit and explore the surface world, which they discover is now dark, windy, desolate, forbidding, and covered with dust.

A man named Zell invites them into his diner and tells them the moon had been struck by something which created an enormous dust cloud now covering the Earth, blocking the sun.

Osterman, in his director's statement, explained that it was my intention to create a narrative that put the viewer in the seat of the experiment itself—one where the audience was never quite sure of whom to trust and unsure if it was all just an elaborate ruse.

"[12] Leslie Felperin of The Guardian rated it 2/5 stars and wrote that the stock characters and predictable backstories make it seem "like watching Solaris performed by sock puppets".