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, via The Playlist we have some new details on Gravity from the website of U.K.-based visual effects company Framestore (The Dark Knight, Avatar) that is seeking new employees to work on the film, revealed that over 60% of the film will be done in CGI and that the opening shot will be over 20 minutes long.

From Framestore:

Framestore is about to embark on one of its greatest challenges yet, Gravity is the next Avatar in terms of ambition. There are many innovative and visually stunning aims for this project.

The entire film will be made here at Framestore. In effect the film, as Avatar was, is 60% CG feature animation with the balance being hybrid CG and live action elements.

Starring Robert Downey Junior, the film is a contemporary survival thriller that follows a woman as she attempts to make her way back to earth after a satellite crash sets off a chain reaction of further crashes. Because it’s set in space, most shots require every element to float in zero-gravity.

But then factor in that this is a stylish Cuarón flick, directed with his trademark languid feel, and you begin to realise the full scale of our challenge. Cuarón’s long and fluid style (the opening shot alone is slated to last at least 20 minutes) leaves no cut points to hide behind. In short, this is a hybrid of a fully animated, photo-real feature film with a blockbusting visual effects movie.

Fortunately, having worked with Alfonso before on Harry Potter and Children of Men, we know one another extremely well. Now we are looking for the best talent in the world to help us realise this massive and beautiful film. Over the next few weeks we are interviewing and looking at reels of those in-house who want to join in as well as making trips to the US, Canada and Australia.

This is CG feature animation meets real world on a large and beautiful scale.

Gravity is slated to hit theaters in 2011.