Full Of Stars

How a mechanical limitation forced “2001: A Space Odyssey” to slow down.

The following is an excerpt from Space Odyssey: Stanley Kubrick, Arthur C. Clarke, and the Making of a Masterpiece by Michael Benson.

Much has been written about 2001’s stately pace, with its spacecraft waltzing across the screen in dignified, measured orbital cadences and Discovery’s solemn progress to Jupiter unfolding with the unhurried regal tempo of an 18th-century monarchal procession leading inevitably to that Louis XIV hotel suite. It turns out, however, that the film’s internal speedometer was limited by an oddly prosaic factor: the flicker factor of stars when filmed at twenty-four frames per second.

Read The Book

Space Odyssey: Stanley Kubrick, Arthur C. Clarke, and the Making of a Masterpiece


Attempts to represent 2001’s starry backgrounds went through several phases, with initial tests involving drilling hundreds of holes into black metal sheeting and positioning lights behind them. This technique was soon judged wanting because as the lens tracked by, the stars either became elliptical due to camera motion, or their brilliance changed, or they twinkled—the latter a big no‑no in the airless environment of space.

With drilled starscapes judged inadequate, another method was tried in which dots of paint were speckled across glass, with the glass then angled and lit from below. But glass being two-sided, each star ended up with a reflected double—another no‑no. Finally, a decision was made to film all the stars on the animation stand, and Trumbull was recruited to airbrush random white specks of paint onto black backgrounds. These were then lit from above. While this produced perfect star fields, it’s also when the speed limit of 2001’s filmic universe became apparent. Most of the shots looked best with those stars moving in one direction and velocity, while the foregrounded spacecraft, filmed separately, moved in another, usually contrary direction and speed. Having grasped this, Con Pederson worked to optimize the best stellar drift directions and speeds, and the same for the spacecraft. He determined, for example, that if Discovery was moving from the left to the right of the frame, and the stars were drifting from the top to the bottom, the result was a kind of floating sensation. After much trial and error, a kind of vocabulary of eight optimal drift directions and speed combinations was established.

Related Segment

50 Years Ago: The Odyssey To Craft ‘2001’

It was at this stage that the realization sank in among 2001’s effects crew that at the standard rate of twenty-four frames per second—which they couldn’t evade, since all film projectors functioned at that speed—fast camera moves were going to be a problem. The issue was that in analog film projectors, each frame actually flickers twice, producing forty-eight flashes of light per twenty-four frames of image. And because of the inherent persistence of human vision, bright white objects such as stars seem to double. At still-faster star motion rates, they triple—an even worse strobing effect. “And so very early in the production, we hit a speed limit that we introduced,” Trumbull recalled. “And that was the law of the movie, to never move faster than that speed so you didn’t ever get double stars.” The stately pulse of 2001’s space sequences, then, was governed by the substrobe rate of their moving star fields.

Asked if this meant that 2001’s waltz rhythm—its courtly choreography of machinery wheeling in approximation of three-quarters time—came in response to their self-imposed stellar speed limit, rather than the film’s pace being edited to match such tracks as “The Blue Danube,” Trumbull said, “Exactly. That’s the story. The waltz rhythm followed the star speed.” (This is not to suggest the tempo of Strauss’s composition was altered—only that Kubrick’s music choices sometimes came in response to a visual rhythm that he’d already determined.)

With this having been established, there remained the question of how to combine those slow-moving star fields with 2001’s spacecraft miniatures. Kubrick and Veevers had improvised a screening room technique in which two projectors were used to ascertain which speeds and directions worked best together: one to project the star fields, the other the spacecraft. But with this kind of live mix, stars flowed visibly across Discovery’s exterior. Obviously, this couldn’t be used in the final film, where it would instantly obliterate the audience’s willing suspension of disbelief, and so an animation technique was devised to mask the stars. It required the production of rotoscope mattes, permitting the frame-by-frame removal of background stars wherever the spacecraft was present in the frame.

[Just how close are we to building Blade Runner 2049‘s replicants, anyway?]

This was all hugely labor intensive, however, and a team of young people was soon brought in to what became known as the “blobbing room.” There they spent innumerable hours meticulously tracing spacecraft outlines onto animation cels (the transparent sheets on which shapes or objects are drawn in analog animation), then blacking them in with paint. Their laborious outlining, and equally monotonous removal of individual stars, took the tedium of traditional handmade animation to a new level. Colin Cantwell used to drop by and check up on the “blobbers,” who, he noticed, had “gotten pretty strange” under the relentless pressure of their star-killing duties.

“The rotoscopers were in there in the dark all the time—just them and some work benches and rows of still projectors—and the most exciting thing they ever got to do was paint blobs of black paint. This was an effort of months and years, and so they were gradually going kind of bananas. Anytime the rest of us got bored or started to think our jobs were mundane, a perfect cure was to go and talk to the blobbers. They were always so glad to see somebody—anybody. All of them became great friends during the production—I’m sure as a means of survival . . . Most of them went from the finish of 2001 over to working on Yellow Submarine—and they were so happy not only to work in the light and look out the window but also to paint in colors. It was a reward for all they’d been through.” 

Benson, Michael. Space Odyssey: Stanley Kubrick, Arthur C. Clarke and the Making of a Masterpiece. Copyright 2018 by Michael Benson. Reprinted with permission.

Meet the Writer

About Michael Benson

Michael Benson is an artist and filmmaker. He’s also the author of Cosmigraphics: Picturing Space Through Time (Harry N. Abrams, October, 2014)

Explore More

The Paleobiologist Who Inspired the Science in ‘Jurassic Park’

George Poinar, Jr.’s lifelong obsession with amber has led to remarkable discoveries of ancient specimens.

Read More