Christopher Nolan's quest for realistic-looking space travel in Interstellar was achieved partially through the amazing models of New Deal Studios, which used a lot of ingenuity to achieve Nolan's very specific requests. One solution included a lot of salt.
FX Guide has an in-depth article on the miniatures used in Interstellar and the film techniques used by New Deal Studios, which is full of interesting little details about the production of the film. For example, of the three vehicles New Deal Studios made — the Ranger, the Lander, and the Endurance — only the Endurance existed solely as a model. In the case of the Endurance, "miniature" is relative: the 1/15 scale model was 14 feet across. Special effects supervisor Ian Hunter explained how they realized in three dimensions the designs already made for the film:
"We took Nathan's basic shape and we worked also with concept artist Steve Burg on the details on the surface," outlines Hunter. "The movie takes place in the near future and Chris wanted it to feel familiar. He wanted the ships to be based on existing NASA details and textures, but applied to these different shapes."
Things were slightly different for the Ranger and the Lander, which had full-sized props that New Deal Studios had to match exactly in the miniatures. Which led to some last minute changes when the full-sized prop was changed on set:
"They built the prop here in the U.S. but had to cut it apart to get on the airplane," recalls Hunter. "Once they put it back together [in Iceland] there were seams left on some of the parts. Chris actually thought that the seams felt like details – that they looked like panel lines. And so he didn't have them fix the seams because he thought they added a little bit of detail. So Chris had Paul Franklin bring us photographs of these seams they had cut into the prop, and we basically incorporated those onto the models."
Another factor that had to be dealt with was that Nolan wanted all the filming to be as much as if real life was being filmed as possible, even for the filming of the miniatures. That meant that, instead of compositing many different shots with different kinds of lighting, everything was filmed in a single pass.
Matching the model shots with the ones Nolan had done with the full-sized props was a constant battle, with Nolan insisting that they attach a camera to the Endurance model as he had done earlier. New Deal Studios had filmed with a crane at a safe distance from the explosion tin the scene in order to protect the camera. Nolan's request had them scrambling to figure out how to both protect the camera and have it bolted to the Endurance model as it exploded:
"We came up with something we called the 'Pelicam'," says Hunter. "We took a Pelican case – a durable equipment case – and we cut a hole in it and mounted our VistaVision camera inside the case. We attached it to the nose of our exploding breakaway Ranger, and then we took a pyrotechnic 'Sweeney' trip and attached it to the nose of the Ranger. And that's what held the Pelicam in place. The Pelicam had a cable going off to the crane above like a tether. So it actually rode the exploding Ranger for several frames, and then at a specific point we could cut that cable and let the camera free to get it out of harm's way. In the end both takes are in the movie."
A final bit of innovation involved filming the Ranger traveling through the black hole, with salt filling in for space debris:
"We stood the model up outside vertically, and again using gravity as our friend, actually bombarded it with different materials as it entered the black hole," explains Hunter. "Chris wanted something organic to keep the shots grounded in reality. So we ended up doing something simple – well – it sounded simple, but it actually got complicated – we dropped salt on it from above. We would stand the model up, and shooting against the black sky we put a lift outside of the range of the key light so that it was in darkness, and then we would off a slant board we would drop salt and shoot it at high speed as it fell towards the ship."
"This weird veil of material would come down and hit the ship, and we shot that on its own separately for Cooper's POV," continues Hunter. "It was a very interesting-looking effect because it wasn't a particle system, it wasn't anything you'd expect to generate from an animation program. It was a strange physical phenomena we were catching. Of course the slightest wind would blow the shot! In order to get the height we shot outside, but it needed to be dead calm to do it."
This is only a small portion of the information contained in FX Guide's full article. Read the whole thing to learn about how they filmed docking sequences, how the shots of the models were matched to the CG shots, and the miniatures human figures that are present — even though you can't see them.