Photo: Jim Spellman/WireImage

To this day, Bill Irwin isn’t quite sure why Christopher Nolan asked him to voice the helper-bot TARS in his latest epic, Interstellar. We can make an educated guess: Irwin is a veteran stage and film actor specializing in vaudeville — he’s been dubbed “the Clown Prince” — whose appearances range from Waiting for Godot to The Good Wife to Subway Stories and Sesame Street. If any character actor could conquer the mechanical demands of the mostly practical TARS (yes, they really built that shape-shifting monolith), a nimble thespian with a degree from Ringling Bros. Clown College would be a logical choice.

Vulture spoke with Irwin about the demands of bringing TARS to life, his intensive work with Interstellar’s special-effects and stunt teams, and finding a sardonic voice to fit TARS’s programmed personality.

Christopher Nolan opted to build a functional TARS instead of creating the robot with CGI. What was he hoping an actor could bring to it?

I’m not sure he entirely knew. The conversation was one of those pivotal life-changers. He talked about [how] the normal way to do this would be to engage an actor to come in during [post-production]. He didn’t want to do it that way. He wanted the actor to be part of the scene. Part of his storytelling genius is he has an engineer’s mind and eye. I saw it as he was describing it. Weeks later, I found myself in L.A. at the special-effects room, and someone had made a plastic model of what Chris and his collaborators had envisioned. From that, the special-effects guys built something out of sheet metal and rivets. Chris would peek in from time to time. In order for it to locomote, there [had to be] pieces of wood on the floor. Chris immediately saw how the pattern of pieces would have to go to make it locomote. But you couldn’t do that all the time, so it then had to have little feet that would extend, deploy, and the thing would have the clearance to walk.

We were pushing this thing around. A wonderful stunt-double, Mark Fichera, whom you see in the movie doubling people in spacesuits, he and I were assigned to this. We would push this thing around. At first it was a matter of gripping a cable that you’d have to grip hard. Then, as it looked more and more like what Chris, [visual-effects supervisor] Paul Franklin, and the designers wanted, it got heavier. At points, the shop guy would say, “I’m gonna have to give you just a minute …” There was a lot of “just a minute”s. Eventually, they transformed it to a compressed air system. It went from squeezing the breaks on an old bicycle to playing a video game.

This sounds a bit like puppeteering. Was the experience akin to any of your past roles?

Not comparable. As I look back now, it’s fascinating that the word puppeteering never came up in that first conversation with Chris Nolan. It didn’t come up for awhile, but it became good shorthand for what we found ourselves doing. It was very visceral, muscular puppeteering because it stood five feet high and was jointed in varying ways and could be reset. You operated it from behind, pushing it, meaning you were attached at the chest and each ankle, so you could push various parts of it, and your hands are on the controls in the back of the machine. Or, if they wanted to look at the machine straight on and have it walk away from camera, you were behind it, backing up.

At some point, there were bits of scratch videos that we’d send over to Chris and the stunt coordinator to show we were earning our per diem while wrestling with the machine. Chris would come to the shop: “What about going through a doorway?” So they quickly built a doorway, and we’d wrestle it through. Mark Fichera is younger and stronger than I am, so he got the tougher assignments where sheer musclepower was involved. But he’d hand it off to me when character movement was involved, as it gradually got to be. We did all this work in Burbank, then suddenly, we had to go to Alberta, Canada, they needed the machine to go through doors and do dialogue at the same time. That first day was trial by fire. The machine wasn’t acting like it had in Burbank. So we’re trying to get it to work while Chris and the AD are telling us that camera is ready. Then Chris keeps giving me dialogue that’s not on any page. It was a great storytelling adventure. I wouldn’t trade it for anything. But some days were easier than others.

This sounds like the most Henson non-Henson endeavor ever.

I’ve never heard Chris Nolan and Jim Henson’s names linked before, but that’s an interesting connection.

Many of the Henson movies use full-body “puppets” that are closer to costumes. That sounds like the case here.

Actually not, which is why I’m hoping some of these videos surface in a well-sanctioned, well-explained milieu where Chris is narrating. We were about 18 inches behind it. There are Henson rigs that work like that. Because I worked on Sesame Street […] I worked around it. There’s a guy named Marty Robinson who built some puppets for me for shows and, in his time, has operated the bigger Sesame Street puppets, where you’re looking at a video screen and giving it life from inside or behind. So I’ve been around it and absorbed some of it.

Scenes where TARS appears on the ocean planet were filmed at Icelandic locations. How did it work operating him there?

We’d be standing in ice-cold water up to our thighs in Iceland, with metal that hadn’t been tried out. We just wanted to do what we were supposed to do. There was the weight plus the water displacement. Aerodynamics were now hydrodynamics. It couldn’t go as fast as we wanted it to go. At one point, I was marking the scene and having fun doing the dialogue — this was actually CASE’s voice, not TARS, it wasn’t my voice heard, but for operating the machine and working with Chris, I’d lay down a guide track. So I’m acting with Wes Bentley and Anne Hathaway, and it’s their first moments on this new planet. They’re striding through the water, and I’m striding, too, but Chris wisely says, “Do you think you can make it go that fast, Bill?” No, I’m running through water, I couldn’t go that fast! We gave him what we could give him on camera and he artfully used that. Then Paul Franklin gave TARS the abilities beyond what we could do as puppeteers.

Chris first described those four plints, solids, and they’re infinitely articulate thanks to highly developed circuitry within the machine. Any time Chris could get something to work on camera, sometimes shoving the thing. “Make the finger come out!”

Through all the practical elements, how did you find time to develop a character?

One of the maddening things was they were always taking the machines apart and putting them back together, to chip them or cannibalize them for other things. There were four machines. One had an arm that folded out from the main body and even had some fingers. They were rarely around to be rehearsed with. We were pains to the special-effects guys. “Any chance we could get a hold of the eight-walker rig?!”

TARS isn’t spontaneous like a human, but he isn’t a droll operator like HAL 9000. Where did the robot’s personality have to land to fit with the technology and themes?

Chris said — and I think he’s prophetic with this — “Robots won’t look humanoid nor anthropomorphized.” That’s what movies have done up until now, but it doesn’t make much sense, engineering-wise. But quite conceivably, they’ll pattern artificial intelligence after human beings. One of my favorite lines is Wes Bentley explaining it to Matthew McConaughey: “They program him to have a personality. They think it makes a unit more cohesive.”

It all started with what was on the page. The script is brilliant. Befuddling, at times, but brilliant. There was personality in this machine. And a point of view. His first job was to apply electric shock and subdue and arrest Cooper. Then he comes to serve Cooper. The persona jumped right off the page, somewhere between a former Marine commander and a high-school gym teacher. We would shoot scenes and lean into it more. Chris took a specific contour of when he wanted to hear a little more of the John Wayne angle, or less. It was programmed to have personality, but it didn’t get overbearing.

You attended Ringling Bros. Clown College in the ‘70s. I’m imagining long days juggling followed by clown-filled frat parties. What is a day of clown college really like?

We went about work very seriously! I was only 24, but it was some of the toughest work I’ve ever done. My collaborator, David Shiner, whom I worked with on Full Moon and our current show Old Hats, he’s writing a film script about people who run a clown school because it’s an inspiring setting. We got up in the morning — this is 1974 — and they worked us. I think they wanted to keep us out of trouble. They didn’t want us on the streets of Venice, Florida. And there were men and women who had been practitioners all their lives showing us what they knew. I’d love to go back and do that again.

Old Hats played off-Broadway in 2013. Is the next step Broadway?

From your lips to the Schubert Organization’s ears. It’s so ready. We took it to San Francisco, and the show became finished. We know what it is so much more. We hope all the stars will align. And there are a lot of stars: scheduling, theater openings, financing, all that. The old codgers we are, we still think we have something to offer with Old Hats.