Jon Hamm joins Natalie Portman in 'Pale Blue Dot'

"Mad Men" star Jon Hamm is in negotiations to join Natalie Portman in the astronaut drama "Pale Blue Dot".

If finalised, the 47-year-old actor will play the role of Portman's fellow astronaut in the film, which will be directed by Noah Hawley, reported Variety. The script has been penned by Brian C Brown and Elliott DiGuiseppi.

The story follows a married astronaut (Portman) who returns to Earth after a mission and begins an affair with a fellow astronaut (Hamm).

The film will explore the theory that astronauts who spend long periods of time in space begin to lose their sense of reality when they return home.

Portman recently joined the project after Reese Witherspoon left it due to scheduling conflicts. Witherspoon, however, is still on board the project as a producer along with Bruna Papandrea.