Space Racer Takes Off

Revenge of the Doom Engine: Forbes.com (E-Gang '08-DIY)

The first time I saw Carmack's bubble suborbital, I chuckled. Not any longer. - JCR

A steady breeze blows across the runway of the tiny municipal airport in Caddo Mills,as id Software founder John Carmack (pictured above) prepares to test-fire a 2,200-pound thrust rocket engine of his own design. The 38-year-old programming genius, who practically invented 3-D computer games with his gory "Doom" and "Quake" in the mid-1990s, is a compulsive tinkerer who used to boost his Ferraris past 1,000 horsepower by bolting turbochargers to them. (Ferrari kicked him off the waiting list for new cars when it found out.)

Now Carmack is playing with rockets. Working out of a ramshackle former gliderport about 30 miles east of Dallas, Carmack has attacked the spaceship business the way a coder assembles software: by designing, building and testing rockets in rapid-fire succession to determine which ones work and which ones don't. (To see our pick of other technowizards, check out "In Pictures: Eight People Inventing the Future.")

It's an entirely different approach from that of Amazon founder Jeffrey Bezos or Paypal founder Elon Musk, who have lavished more than $100 million each on Blue Origin and SpaceX, their efforts to launch satellites and passengers into orbit.

Carmack has spent just $3.5 million on his Armadillo Aerospace so far, but he has more launches under his belt than Bezos and Musk combined. Of the 30 commercial launches reported to the Federal Aviation Administration since 2006, Armadillo has 12 and Bezos' Blue Origin has three. Elon Musk's SpaceX has pre-sold 11 launches, but its three attempts have so far failed, including an Aug. 2 launch where the rocket's second stage failed to separate. Carmack has made about 100 more flights with his rockets tethered to the ground by strong chains. (For a peek at Carmack's adventures, click here.)

"The reality is John has more operational experience with these things than anybody else," says John Gedmark, an aerospace engineer who runs the Personal Spaceflight Federation, which represents Armadillo, SpaceX and most of the other entrepreneurial space efforts.

On this hot June evening, Carmack is testing a modified engine he's developing for the Rocket Racing League, which plans a series of rocket-powered airplane races. The engine is, in large part, made up of a pair of aluminum spheres 4 feet in diameter. One is filled with liquid oxygen, the other with alcohol. They protrude from the back of the small plane like a malignant tumor.

"Pad 3, verify fire crew ready," Carmack says into a walkie-talkie as his fingers fly over a Panasonic laptop that communicates with the engine via a wireless link.

"Chill LOX plumbing," he says. "Begin firing sequence."

The engine lights up and a blue flame spews from the nozzle with an unearthly howl. The sound increases to a roaring scream as Carmack throttles the engine. Then it burps, the flame goes out, and an embarrassing shower of alcohol spews over the tarmac. It smells like a vodka truck has hit a tree.

"Just let the fuel run out," Carmack says, discouraged, as the ground crew hoses down the scene with water.

It's a failure but an instructive one. Several hours of furious coding later, Carmack has identified the cascade of events that caused a liquid oxygen valve to close (ironically, a fail-safe program malfunctioned) and has rewritten the software and prepared the engine for six subsequent test-firings.

This sort of rapid turnaround makes Carmack the wizard of low-cost rocketry. He came close to winning the $2 million X Prize Foundation's Northrop Grumman Lunar Landing Challenge last year by flying an alcohol-fueled rocket 150 feet in the air to a landing pad 300 feet away. He was forced to scrap the return trip--required to collect the prize--after a graphite engine nozzle disintegrated. He's since corrected the problem by switching to a more bombproof aluminum nozzle.

Dressed in shorts and sneakers, with thick glasses and unruly hair, Carmack looks like a forgotten character from the 1980s cartoon Beavis and Butthead. Speak with him for a few minutes, however, and it's obvious he has an off-the-charts IQ and an almost intuitive sense of the physics behind controlled rocket flight.

Carmack grew up playing with Apple II computers--he was sent to a juvenile home at 14 after breaking into a school to steal one--in various suburbs of Kansas City (both in Kansas and Missouri). He attended a couple of semesters of college before quitting to become a freelance game designer.

It was in the late 1980s that Carmack became known as a coding wizard, at one point modifying Nintendo's (other-otc: NTDOY.PK - news - people ) Mario Bros. game to play on a PC, which then was believed to be too slow to handle the graphics. Nintendo (like Ferrari later on) wasn't amused, so Carmack and several friends formed id Software in 1991. They went on to sell millions of copies of "Doom" and "Quake," the games that defined the "first-person shooter" genre.

Carmack still controls id and codes 40 hours a week, earning about $2 million a year. He considers the software business to be mature, however, with little room for the radical advances he helped spur in the early 1990s. Rocketry is more exciting, he says, because it has been stalled for the last 30 years with NASA's bureaucracy and technological dead-ends like the Space Shuttle. "When somebody makes a cheap, reusable launch vehicle that can get up to orbit, all sorts of things will change," Carmack says. "Big-deal things."

His approach is entirely different from Musk, who plans to begin launching commercial satellites into orbit at $8 million a pop by 2012. Musk has hundreds of aerospace engineers on the payroll but has only flown his 90-foot Falcon rocket twice. Both times it had to be destroyed in flight because of systems malfunctions.

Carmack, however, fires something off most Tuesdays and Saturdays, adjusting his designs in response to each failure. He can often be seen at the controls of a $58,000 Haas automated milling machine--a birthday gift from his wife, Anna--making rocket parts. True to form, he types in commands using machine code.

He writes almost all of the code himself, including the complex instructions that translate inputs from a laser gyroscope to actuators that steer the ship by moving the nozzle at the bottom. (At $12,000, the gyroscope is the single most expensive item on his rockets.) Carmack buys most of his components from McMaster-Carr, an industrial supplier with overnight delivery. The guidance computer is a homemade box with a 486-class Intel (nasdaq: INTC - news - people ) processor, chosen, Carmack says, after he learned that newer processors have plug-in memory chips that can wiggle loose under heavy vibration. The nozzle-steering actuators are identical to the ones that open miniature stop signs on a school bus.

While rocket science has a reputation for being tough, Carmack insists coding computer games is tougher. "Some of the things I do in software are really hard. You're saying, 'This is complex, this makes my brain hurt,'" Carmack says in his angular Midwestern accent. "This is simple, it's just not-easy."

It's difficult to see how any of Carmack's current rockets could make it into space, since most are naked structures containing a few spherical fuel tanks and a nozzle at the bottom. But Carmack insists that once he works out how to build and control an inexpensive rocket, he can rapidly scale the design into a working spaceship. He's already thinking about mounting a 6-foot diameter Lucite sphere on one to haul passengers into space.

Would anybody be reckless enough to get on board?

"There's a line," Carmack says.