Commentary: Metric Mayhem | Flight Today | Air & Space Magazine

Commentary: Metric Mayhem

Practically the entire world uses the metric system. Is it time for the United States to follow suit?

Air & Space Magazine | Subscribe

Not long ago, I was writing a story for this very magazine about the delicate extraterrestrial dance of a U.S. spacecraft around a potato-shaped asteroid named Eros (see “Hang a Right at Jupiter,” Dec. 2000/Jan. 2001). The simplicity of the spacecraft’s course stood out in a universe that is rarely simple and convenient: The boxy craft would circle 100 kilometers from the asteroid’s cratered surface, then fire its engines to drop into an orbit 50 kilometers above the tumbling space rock.

Finally, I thought, I don’t have to worry about how to round off some impossibly large number such as the speed of light (299,792.458 kilometers per second) or the distance between Earth and the sun (149,597,870 kilometers).

At least that’s what I thought until the editors got hold of the story and reminded me that this magazine does not use metric units. Convert all kilometers to miles, they said, all meters to feet, and all kilograms to pounds.

Why not use metric, I asked. All the scientists working on the spacecraft use metric. All their written materials use metric. Every other country that operates in space uses metric. Their reply: Because we have always done it the other way. It’s what our readers understand. It’s the American Way.

Lengthy investigation suggests that this is about the only explanation for why the United States as a whole evades the metric system while most of the rest of the world embraces it—because we have always done it the other way. We’re like a crotchety old hermit. The rest of the international neighborhood works together and speaks the same language while we huddle in a dark, outdated house at the end of the street (which we share with Liberia and Burma, the only other two nations that have not gone metric), mumbling our own inscrutable tongue of inches, feet, yards, miles, links, rods, furlongs, pecks, bushels, bolts, barrels, fathoms, leagues, acres, ounces, pounds, tons, cups, bales, pints, tablespoons, gallons, hands, chains—most of which have no logical relationship to one another—and all the other aged terms of what is often called the Imperial, or English, system but which metric advocates derisively refer to as FFU (Fred Flintstone Units). So I could have probably said to my editor, “That’s typical FFU.”

But of course I didn’t.

Such lack of backbone may be why the U.S. portion of the International Space Station is built in Imperial Units while the rest of the super-expensive structure has been constructed in metric. About 10 years ago NASA gave serious thought to the idea of building the whole thing in metric, but decided that would drive the cost way up. All the NASA contractors were tooled to build parts in inches and pounds; converting to metric would have required revised designs and new machines. So instead they developed an elaborate and costly computer-modeling and cross-checking procedure to make sure that metric and Imperial parts fit together and work properly.

Of course, an all-out metric conversion would carry costs of its own. No one has ever solidly estimated it, just as no one has estimated the loss of U.S. trade dollars due to the unwillingness of other nations to take shipments in pounds and gallons. Certainly we would need to recalibrate scales, gas pumps, and the like. There’s always a cost to repairing a sinking ship, but the cost of not repairing it may be far greater.

Right now the Russians are controlling the space station, figuring propulsion exclusively in metric units. Once the onboard laboratory (expected to have launched January 18) is up and running, the U.S. will take over control exclusively in Imperial units. When I asked spokesman Kyle Herring of NASA’s Johnson Space Center in Texas what would happen if there were some confusion between the two, if a maneuver supposed to be carried out in pounds of thrust were actually done in kilograms or the other way around, he explained that the station’s propulsion system operates at such low thrust that even a major miscalculation couldn’t send it spiralling into the atmosphere. But it doesn’t always take a major miscalculation to reveal the cost of our old-fashioned tendencies. Remember NASA’s Mars Climate Orbiter? As it headed toward its rendezvous with the Red Planet in the summer of 1999, navigators calculated the effects of subtle maneuvers to adjust its trajectory, based on data from contractor Lockheed Martin. The data was supposed to be in metric units, but it wasn’t, so each maneuver ended up throwing the craft farther out of whack, putting it more than 100 miles off course by the time it arrived at Mars. The $125 million probe probably burned up in the Martian atmosphere.

The problem is that while Lockheed Martin’s space division operates entirely in metric, its manufacturing side and many of its contractors use Imperial Units because rebuilding sophisticated hardware in metric would be wildly expensive, says Edward Euler, the company’s program manager of the ill-fated Mars mission. For similar reasons, NASA requested proposals for its next generation of space shuttles in inches, feet, and pounds even while most of the agency’s own scientists use metric. “You really have two NASAs—one English and one metric,” says Euler, who adds that Lockheed Martin has the same problem. “We can’t buy our nuts and bolts to the metric standard—that’s the place, on the commercial and manufacturing side, where there’s really resistance.”

NASA and Lockheed Martin aren’t the only ones suffering. About 20 years ago a Canadian airliner nearly ran out of fuel when U.S. ground crews filled its tanks with 22,300 pounds of gas rather than 22,300 kilograms. Corporate pilot Michael Payne says that when flying in Russia or China, air traffic controllers give altitude instructions in meters, leaving U.S. pilots to convert them into feet.

Among the first advocates for metrication in the United States was Thomas Jefferson, who as secretary of state asked Congress in 1790 to adopt a decimal system of weights and measures “and thus bring the calculations of the principal affairs of life within the arithmetic of every man who can multiply and divide plain numbers.”  Congress waited 76 years before responding with the Metric Act of 1866, which legalized but did not require metrication. A century later, Congress passed the Metric Conversion Act of 1975 followed by a 1988 bill making metric the “preferred system of weights and measures” and beginning a voluntary conversion to metric, a forthright step everyone promptly forgot.

We’re now left with a strange metric-Imperial amalgam that actually includes more metric measurements than you might guess: We buy soda in liters, we measure film in millimeters, and our track stars run 100 or 1,000 meters. Curiously, illicit drug dealers have gone mostly metric, and it clearly hasn’t caused them any financial hardship.

But imagine cheering at the Indy 804.7 or reading 96561 Kilometers Under the Sea, says Matt Bartmann, who with his brother Dan created the website metricsucks.com as a joke to bring attention to their surplus-magnet business but then decided the metric system really does suck. There’s no reason to upend our culture simply to conform to the rest of the world, they concluded. It’s enough that liquor buyers already get ripped off by the metric system: For example, a “fifth” is actually 750 milliliters, slightly less than a true fifth of a gallon. “We never really liked it,” Bartmann says. “Now we have good reason not to like it.”

If it mixes up the nation’s top space engineers, though, how can we expect schoolchildren to grasp the outdated Imperial system? That’s the question raised by Lorelle Young, president of the U.S. Metric Association, who cites studies showing that our students could save a semester’s worth of school if they learned metric, where everything is based on multiples of 10. “I always like to compare it to when computers came in,” she says. “People said, ‘It’s too hard to learn.’ Now you couldn’t imagine life without computers.”

NASA, which was supposed to go all metric in 1996, adopted a new policy after the Mars Climate Orbiter “mishap” that requires “consideration of the metric system” for all new programs “unless such use can be demonstrated to be impractical or likely to cause significant inefficiencies or loss of markets to U.S. firms.”

Backbone, anyone?

A few years back, the late Brian Welch, head of NASA’s news operations, issued a directive saying the agency would use inches and pounds in news releases because that’s what the public and the press understand. He was deluged with critical e-mail from metricationists. “I did not think it was our job to unilaterally drag the American public into the metric system,” he recalled.

That may be, but doing nothing is almost always the easiest way to go. And as long as we can do nothing, we probably will. We’re so used to everyone else adapting to our ways, we may simply have forgotten how to adapt ourselves. Oh, that spacecraft orbiting the asteroid? Listen up, editors: It circled 62.1 miles from the rock and then descended to a 31.05-mile orbit.

At least I think that’s right…

 

Comment on this Story

comments powered by Disqus