Liquid hydrogen is one of them. Four years after the disastrous crack-up of space shuttle Columbia, NASA's flying flatiron has suffered another self-inflicted wound,apparently for the same stone cold reason. Little wonder astronauts have been known to have a few stiff drinks, but here's a sober account of the present problem from one in training . And-- my Op-Ed account of what was supposed to be the last shuttle autopsy; click the image at the left to see the result of the current launch damage .
Too Strong is Never Wrong
The Wall Street Journal 28 August 2003
By Russell Seitz copyright 2003 the author & Dow Jones Inc.
Seeing is believing, but whether it's 9-11, or the Columbia disaster, it can take months to comprehend what takes seconds to witness .The more you replay the slow motion video of NASA's test gun shooting a hole in a space shuttle wing, the harder it is to accept what a chunk of glorified Styrofoam did to Columbia. It's as though one of the Titanics lifeboats rammed and sank the iceberg. But watch we must--to avoid future disasters it is vital to understand past ones.
The space shuttle may look like a flatiron clad in firebrick, but it's really a flying soufflé. Its wing tiles have the density of Balsa wood, and the insulation on its liquid hydrogen tank makes cork look heavy. What punched a hole in the wing weighed in at just two pounds per cubic foot- so light that the 1,600-mile an hour air stream screaming by stopped it almost cold. Whereupon the oncoming wing hit it at 500 miles an hour.
When physics happens, tragedy can unfold with the bizarre internal logic of a Road Runner cartoon.It is easy to forget that the weaker things are, the denser they can get.
Half the foam retained the innocent consistency of a meringue, but the other side ,struck by the wing, was squashed for an instant into a mass of compressed plastic stiff as a sculptor's mallet. Not just in Norse myth do things harmless as mistletoe transform and deliver killing blows.
Cold has been NASA's nemesis since 1986 when a giant'o-ring' rubber band turned rigid on a frosty morning. Its failure to seal a vital joint caused the Challenger explosion. Seeing what warm foam did, this may make such effects seem moot as the caliber of pistol in Russian Roulette. Yet foam spiked with ice or with solidified gas is a bullet worth dodging- liquid hydrogen can freeze the very air
NASA's hydrogen-fueled rockets rise skyward on expanding plumes of water vapor. It's a sight that antique railroad buffs may admire, but it's strange to find NASA, that avatar of the space age, using fire and water to raise steam to leave the Earth. Whatever became of physics?
The answer may be that 1986 saw a worse disaster than the Challenger crack-up: Chernobyl. It was a vintage year for Apocalypse fans for the end of the Soviet Union was indeed nigh and the large sick bear's antics were growing alarming. "Nuclear Winter" was riding on the coat-tails of "The China Syndrome" like an advertising banner behind a witch's broom, when some Ukrainian apparatchiks disabled the safety systems of a nuclear power plant. Their criminal mischief led to the demonizing of nuclear space research. So here we sit in the 21st century,wondering why we aren't on our way to Mars.
The space-shuttle bureaucracy is part of the problem. It would rather replace its backfiring warhorse than face a revolution in propulsion and design. Bridge builders use a safety factor of 400%, but for sheer lack of thrust, NASA's designers are still stuck with 40% and musthold their peace when good people go down in flames. With two shuttles gone, it takes more of the right stuff than ever to fly rockets built out of perilously close to no stuff at all.
This cockleshell construction is the antithesis of nuclear submarines. They're built like tanks yet tear around at flank speed for decades on what amounts to a single tank of gas, simply because nuclear forces are so strong. A million-fold increase in energy density enables a negligible mass of fuel to move a mighty tonnage. The reverse is true of the rockets of today. Care to buy a car that gets a ten-thousandth of a mile per gallon?
NASA has long worked wonders with wisps of carbon fiber and thin scantlings of other advanced materials, but the Holy Grail of designers, almighty strong and feather light Unobtanium, is simply a myth. It's sheer mass that continues to matter. Good as strong materials are, using more of them is better. The underpowered aircraft of yesteryear had wings of spruce and silk only because their engines could lift no more. Today's spacecraft are not much better. NASA needs more powerful propulsion and more formidible spacecraft to assure future astronauts a safe return.There are worse hazards than flying foam between here and Mars.
The changes in NASA's culture that the Columbia Accident Investigation Board counsels are vital to a safe return to space, but NASA's only real nemesis remains the force of gravity. There is plenty of physics to apply to the task of overcoming it, , ranging from ground-based lasers and energy stored in isotopes to the ion drive that will gently loft Europe's first mission to the moon .
Such new technologies may set the proverbial rocket scientists of Cape Canaveral free to listen to the wisdom of their colleagues, the shipwrights Cap Finisterre. On that unforgiving Breton shore, they still build even the smallest craft out of massive timbers. Ask why and they reply: "Trop fort c'est pas manqué." Too strong is never wrong when strong enough can break.