The Star Gate in 2001: A Space Odyssey: How Light Became a Corridor

How the Star Gate was made: Douglas Trumbull's slit-scan machine

Kubrick knew what he wanted before anyone knew how. Trumbull wrote it all up for American Cinematographer in 1969: “Kubrick had said that he wanted the camera to ‘go through something’, but nobody knew quite what or how.” Trumbull, one of the film's special effects supervisors and still in his twenties, had heard, vaguely, about something the animator John Whitney had tried, “a slit that moved across the frame while something moved behind it in a pattern that distorts in an odd way,” and he asked himself one question: “Why couldn't that pattern be made to move in depth, in space, so to speak?”

He tried it on an Oxberry animation stand at MGM in England with a Polaroid test camera, cranking a moiré pattern and a slit around by hand with the shutter open, and ended up with a stack of Polaroids. “One of the simplest applications of the technique resulted in flat walls of exposed light.” Kubrick saw them and said, “Do that. Go ahead with it!”

The real machine had panes of glass five and a half feet high and twelve feet long on huge tracks, and worm gears fifteen feet long, flown in from Detroit, to move the camera and drive the glass in sync. Trumbull called it “a great, huge, clumsy rig,” and then, “but it worked.” In his first article, in June 1968, he named the camera, a standard 65mm Mitchell, and the pace: about a minute to expose each frame.

What slit-scan is: a wall of light from a slit and a moving camera

Trumbull's name for the general idea was animated streak photography, the way scientists photograph flow by leaving the shutter open while something moves. He defines the slit-scan version: “An almost infinite plane may be created by moving an illuminated image behind a very narrow, long slit opening, while the entire mechanism moves toward the camera.” Then, “we call this the slit scan.”

Inside one frame, the camera moves in and the slit's image travels from the centre of the film out to the edge, while the artwork slides past behind it. “In this way the artwork is literally scanned onto the film, creating a receding plane of exposure.” Each pass is like shooting a wall fifteen feet long from about an inch away. The artwork only moves four or five inches in that time, so a small piece of it gets stretched down fifteen feet of wall, and the streaks are why “even a single frame of film (which is a very static thing) looks like it is going very fast.”

The motion comes between frames. After each exposure the machine advances the film, nudges the artwork along and runs again, and the size of that nudge sets how fast the walls rush past. Each wall was its own exposure. “It was not possible to shoot two walls at the same time because of the angle at which the camera has to shoot the artwork,” so every Star Gate shot was exposed twice, sometimes with two different pieces of art and sometimes with the same piece, “flopped, with the colors changed.”

On Expose one frame, watch the bright line, the slit's image: it crawls out from the centre and then races for the edge, because the outer half of each wall is exposed in the last inch and a half of a fifteen-foot move. Drop the speed to nothing and the corridor freezes; all the motion lives in the step between frames.

Paul Franklin, who used slit-scan for the tesseract in Interstellar decades later, explained it to Screen Daily: “Those photos record one point in space across many moments in time, where a typical photo is a moment in time across many points in space.”

What was behind the slit: op art, moiré and a printed circuit

The machine was the easy part. Trumbull says the main problem “had nothing to do with the machine we built, because that worked just fine; it had to do with the actual artwork.” Kubrick worried about what people would see in that sequence, and they experimented for a long time. One test was pure texture, and Kubrick's verdict was short: “That looks too much like carpets going by.” They junked it.

So they built a light board about six feet by eight and started collecting: high-contrast op art paintings, moiré science kits, curves and loops drawn from scratch, blown-up electron microscope photographs of molecules and crystals. The best trick was feeding the slit its own results. Shot through the slit onto Polaroid, a photograph of a printed circuit came out as an abstract pattern only vaguely like a circuit, and plain concentric circles turned into an op art design “that would be very difficult to draw or paint.” About a hundred Polaroids were pasted together and rephotographed onto one big negative, combined with others into a huge mosaic, and coloured last with sheets of plastic cut to the shapes of the design.

The op-art strip in the machine above is built the same way, a mosaic of rings, moiré and lattices under cut gels. The less art passes the slit, the further each scrap of it is stretched, and the more it turns into pure speed.

The Star Gate landscapes: Monument Valley and the Hebrides in the wrong colours

After the corridor come the clouds of exploding colour. Trumbull kept their method quiet in 1968, saying only that they “involved the interactions of certain chemicals within a camera field of a size no larger than a pack of cigarettes.” Then come the landscapes, real places filmed from the air, in colours that don't belong to them: “The final series of shots before Keir Dullea ends up in his unusual predicament were done by shooting some fairly unusual aerial scenes, and then juggling the color filters in the YCM duping process. It took months of experimentation to find the key to this technique.”

Kubrick's archive at the University of the Arts London keeps the paperwork for one of those places: technical notes, dated 1 December 1967, on grading the masters of footage of Monument Valley, Utah, “filmed as part of the Stargate sequence.” The others came from the Hebrides and the mountains of northern Scotland.

YCM is how a colour film was split for safekeeping and duplication: the picture is copied onto three black-and-white films, one record for each colour of light, Y for blue, C for red, M for green. To get colour back you print all three onto new stock, each through its matching filter. Print a record through the wrong filter and the colours trade places while the detail stays exactly where it was, which is why the Star Gate's landscapes still read as real land.

Try Turn all three and Monument Valley's red rock goes violet under a green sky. A few taps get you somewhere strange, and Trumbull's team spent months there.

After 2001: slit-scan from Doctor Who to Interstellar

After 2001 Trumbull built a lighter slit-scan machine with a longer track and automatic follow-focus, and ran the ABC network's logo through it for TV spots “very much like the ‘Star-gate’ sequence.”

In 1973 Bernard Lodge redesigned the Doctor Who titles for the BBC, inspired by the Star Gate, filming light refracting in plastic through slots in black card on a rostrum camera, and for the 1974 version he cut his slits in the outline shapes of the Doctor and the TARDIS. In 1987 John Knoll at Industrial Light & Magic slit-scanned a model of the Enterprise-D to stretch it into warp for Star Trek: The Next Generation.

Trumbull's Jupiter: a painting turned on a lathe

Before any of that, the film needed a Jupiter, and several painters tried and failed to paint the way clouds change shape, colour and tone as they turn around the edge of a sphere. So Trumbull made one with a variation of the slit-scan, “based on the principle of the lathe.” If a line of light makes a plane when you move it through the frame, a half circle of light turning on a pivot makes a sphere.

His half circle was a strip of paper a sixteenth of an inch wide on the edge of a disc of black aluminium. A flat painting of Jupiter's surface, as a colour transparency, was projected onto that thin line, so only a sliver of the painting landed on it at any moment, and as the disc turned, the painting moved across the line at the same time, “just as the flat pane of glass traverses behind the slit in producing the ‘Star-gate’ effect.” He painted the Great Red Spot, “the Red Eye of Jupiter,” himself, as a perfect circle, knowing the sphere would stretch it into an oval. The machine turned a full 180 degrees while the painting moved only 90 to 100 degrees' worth, so the whole thing got pulled around the planet, and in his words it “became sweeping, as if there were terrific wind forces about the planet.”

He stopped at 180 degrees on purpose. Carry the line all the way round and you'd see the front and the back of the planet at once, and it would look transparent; he wanted Jupiter solid. A year after the film, the thing that pleased him most was that “nobody has ever questioned that it was anything but Jupiter,” and he added something that sounds strange now: “the very best actual photographs ever taken of Jupiter are very bad. They're extremely fuzzy and you can hardly see any distinguishing features.”

Jupiter before the film: Donato Creti's Astronomical Observations

Long before anyone could photograph Jupiter, a painter in Bologna put it in the sky. In 1711 Count Luigi Ferdinando Marsili asked Donato Creti for eight small canvases, the Sun, the Moon, five planets and a comet, each hanging in the night over a landscape where tiny figures look up through telescopes. The astronomer Eustachio Manfredi showed Creti what the planets looked like through one. Marsili gave the set to Pope Clement XI to convince him the Church needed an observatory, and it worked: Clement funded Bologna's Institute of Sciences and its observatory. The paintings are in the Vatican Museums today.

Creti painted Jupiter in bands, with a dark spot. In 1665 Giovanni Domenico Cassini had found a dark oval at the latitude where the Great Red Spot sits today, and astronomers watched it until 1713, two years after this painting. When the American Geophysical Union announced a 2024 study of where the Great Red Spot came from, it used Creti's Jupiter to show that old spot, “a red spot is shown prominently on Jupiter.” The study argues the spot seen now is a different storm, watched since 1831.

The painting and the film are doing the same thing. Neither Creti nor Trumbull could see Jupiter properly: Creti had a telescope, Manfredi's eye and a pope to persuade, Trumbull had fuzzy photographs and a turning disc of paper. Both painted a spot on Jupiter before anyone had a sharp photograph of the planet, and when Voyager 1 photographed the Great Red Spot close up in 1979, the “terrific wind forces” Trumbull had invented were there, swirling around the oval. Both put you in front of the planet at night, small, looking up, which is where Kubrick wanted his audience. He called the film “basically a visual, nonverbal experience” that “hits the viewer at an inner level of consciousness, just as music does, or painting.”

The print to hang beside the Star Gate is This New State. Seen from below, a figure of molten red rock rises out of a forest clearing into a blue sky full of planets and a falling star, its body turning to fire as it climbs: a man going through the light and coming out the other side as something else, which is what the corridor does to Bowman.

Frequently asked questions

How was the Star Gate sequence in 2001 made?

With slit-scan photography, on a machine Douglas Trumbull built: a 65mm camera with its shutter open moved toward a narrow slit while backlit artwork slid behind it, leaving a receding wall of light on the film. Each wall was its own exposure, and a frame took about a minute.

What is slit-scan?

A form of what Trumbull called animated streak photography: a long exposure in which an image moves behind a narrow slit while the camera moves relative to it, so one frame records many moments. On a moving camera it turns flat artwork into a plane that seems to recede to infinity.

Where were the Star Gate landscapes filmed, and why are the colours strange?

They are aerial shots of real places, including Monument Valley, the Hebrides and the mountains of northern Scotland. Trumbull says the colours came from “juggling the color filters in the YCM duping process”, printing the picture's separate colour records back through the wrong filters.

What music plays during Jupiter and Beyond the Infinite?

György Ligeti. The Kyrie from his Requiem plays as Bowman nears the monolith at Jupiter and runs straight into Atmosphères as he enters the Star Gate. The 1996 soundtrack CD joins them, with an electronically altered Aventures, in one track, “Jupiter and Beyond.”

Read next

• Kubrick's lighting, HAL's red lamp, the f/0.7 lens and the candles in Barry Lyndon.
• Is Gargantua Real? The black hole in Interstellar, next to the real ones.
• Paintings of space, from Elsheimer's Milky Way to Webb, with Creti's Saturn and its telescope.

References

• Douglas Trumbull, “The Slit-Scan Process as Used in 2001: A Space Odyssey, and Beyond,” American Cinematographer 50, no. 10 (October 1969): 998–1026: theasc.com
• Douglas Trumbull, “Creating Special Effects for 2001: A Space Odyssey,” American Cinematographer 49, no. 6 (June 1968), reprinted at Cinetropolis
• Hillary Brady, “The Making of 2001's Star Gate Sequence,” National Air and Space Museum, 19 May 2018: airandspace.si.edu
• Stanley Kubrick Archive, University of the Arts London, “Monument Valley Masters Grading,” SK/12/8/1/40, 1 December 1967: archives.arts.ac.uk
• Jerome Agel, ed., The Making of Kubrick's 2001 (Signet, 1970), on the landscape locations, via Wikipedia
• Giovanna Fossati, From Grain to Pixel: The Archival Life of Film in Transition (Amsterdam University Press, 2009), on separation masters
• Vatican Museums, “Donato Creti, Astronomical observations”: museivaticani.va
• William B. Ashworth Jr., “Eustachio Manfredi,” Scientist of the Day, Linda Hall Library, 20 September 2019: lindahall.org
• American Geophysical Union, “Jupiter's Great Red Spot is not the same one Cassini observed in 1600s,” 17 June 2024, on Sánchez-Lavega et al., Geophysical Research Letters 51 (2024) e2024GL108993: news.agu.org
• NASA/JPL Photojournal, PIA00014, “Jupiter Great Red Spot” (Voyager 1, 1979): photojournal.jpl.nasa.gov
• Marcus Bernard, “Doctor Who: 50 Years of Main Title Design,” Art of the Title, 26 November 2013: artofthetitle.com; “Bernard Lodge,” BBC Motion Graphics Archive, Ravensbourne University London: ravensbourne.ac.uk
• Jay Stobie, “ILM Celebrates 60 Years of Star Trek, Part 2: From Next Generation to Alternate Realities,” Industrial Light & Magic, 10 September 2026: ilm.com
• Ian Sandwell, “The VFX of Interstellar,” Screen Daily, 23 January 2015: screendaily.com
• David Parkinson, “Douglas Trumbull, visual effects visionary behind 2001 and Blade Runner, 1942 to 2022,” BFI, 9 February 2022: bfi.org.uk
• Joseph Gelmis, The Film Director as Superstar (Doubleday, 1970), interview with Stanley Kubrick