The Astronaut ending explained: Was Sam always an alien?

The Astronaut is a sci-fi film that follows an astronaut, Sam, a NASA astronaut who returns to Earth after a failed mission and begins to experience strange physical and psychological changes that challenge her sense of identity.

Disclaimer: This article contains major spoilers for The Astronaut.

The main question driving The Astronaut is whether Sam Walker, the returning astronaut, was infected by an alien presence during her mission or if she was never human at all. By the final act, it becomes clear that Sam herself was an alien living in disguise since childhood.

Her hallucinations, spreading bruises, and telekinetic abilities signal the gradual breakdown of her human form. When she finally learns the truth, Sam leaves Earth and reunites with her alien family, concluding the story by restoring her true identity.

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The Astronaut: Sam Walker’s return to Earth

A still from The Astronaut (Image via YouTube/Vertical)

The film starts with Sam crash-landing in the Atlantic Ocean when wreckage from her spacecraft impacts her while re-entering. She is rescued by the Coast Guard and taken to a safe medical facility for treatment. When she wakes up, she is unable to remember what happened during her mission.

Officials, including General William Harris, intervene and quarantine her. Soon afterward, Sam is moved to a secluded countryside house, where she is told to remain until the inquiry is complete. As she settles in, Sam starts to develop strange symptoms. She develops a dark blotch on her arm and gets flashes of disorientation and shooting visions of dark shapes in the woods on her property.

She also discovers that she can move small objects around telepathically. When she goes out to explore her location, she discovers that the property is equipped with hidden cameras, and it appears that her isolation is part of some larger observation experiment.

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The Astronaut: The hidden purpose of Sam’s mission

A still from The Astronaut (Image via YouTube/Vertical)

Sam's illness improves as her memory begins to return. While having a conversation with her husband, Mark, she remembers that her initial assignment was to transmit a deep-space message intended for unknown living things. She starts to believe that her message was intercepted and that something has returned home with her.

Her doubts escalate when an infestation of insects envelops the home, covering all the windows before suddenly dying off. The event unsettles Sam and makes her believe her case is linked to forces outside Earth. General Harris immediately comes with a delegation of scientists to perform additional tests. After they visit, Sam starts developing disjointed flashbacks that start opening up the truth of what had happened to her in the past.

Through these recovered recollections, Sam discovers an alien vehicle that crashed in the Mojave Desert years ago. Crash survivors were pursued by government officials, and one of the creatures, a young alien who could adopt a human form, was saved by Harris and brought up as Sam Walker. Her present visions are not illusions but glimpses of these repressed events returning to her consciousness.

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The Astronaut: Revelation and transformation

Sam takes refuge in an underground bunker when another power outage triggers the home’s alarm system. She observes through surveillance monitors that three dark figures have entered the property.

Escaping through an air vent and into the surrounding forest, she encounters the figures, who communicate telepathically that they are her biological family. As they approach, her human disguise begins to fail, revealing her original alien form beneath the surface.

Mark and their daughter Izzy arrive at the scene as General Harris tries to capture Sam. He admits that her mission was designed to attract the remaining extraterrestrials so they could be contained. Mark intervenes, stopping him.

Recognizing that her transformation cannot be reversed, Sam says goodbye to her family and boards a waiting spacecraft with the alien beings. The ship ascends into the night sky while Mark and Izzy watch from the ground.

The Astronaut's conclusion clarifies that Sam’s physical changes were not caused by an external infection but by the collapse of her human disguise. By leaving with her true family, Sam ends the containment and observation cycle, defining her existence on Earth. The film closes with her departure, bringing resolution to her hidden past.

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