Back in March we told you that Robert Downey Jr. (Iron Man 2) signed on for Alfonso Cuaron‘s (Children of Men) new film, Gravity which was written by Cuaron and his son Jonas. RDJ is set to play the leader of a team posted at a space station. While he and a female colleague are traveling outside the space station, the other team members are decimated by debris from an exploded satellite. At one point, Angelina Jolie (Wanted) was to play that female colleague opposite RDJ but has since passed on the project.

Now, THR is reporting that Blake Lively (Green Lantern) and Scarlett Johansson (Iron Man 2) are both eyeing the female lead role in Warner Bros.‘ sci-fi thriller. Johansson and Lively have both tested for the role, and a decision is expected within the next week or two.

Gravity is slated to hit theaters in 2011.