CARLSBAD, N.M. — Roger Nelson has a simple and unequivocal message for the people of the year 12006: Don't dig here.
As chief scientist of the Waste Isolation Pilot Plant, Nelson oversees a cavernous salt mine that is the first geological lockbox for the "fiendishly toxic" detritus of nuclear weapons production: chemical sludge, lab gear and filters laced with tons of radioactive plutonium.
Nearly half a mile underground, workers push waste drums into crystalline labyrinths that seem as remote as the moon. A faint salty haze glows in powdery beams from miners' headlamps and settles on the lips like a desert kiss. Computer projections predict that within 1,000 years the ceilings and walls will collapse in a crushing embrace that seals the plutonium in place.
But plutonium remains deadly for 250 times that long -- an unsettling reminder that some of today's hazards will outlast the civilizations that created them. The "forever problem," unique to the modern technological age, has made crafting the user manual for this toxic tomb the final daunting task in an already monumental project. The result is a gargantuan system that borrows elements equally from Stonehenge and "Star Trek."
Communicating danger may seem relatively straightforward, but countless human efforts to bridge the ages have failed as societies fall, languages die and words once poetic or portentous become the indecipherable marks of a long-forgotten scribbler.
To future generations, warnings about Nelson's dump may seem as impenetrable as the 600-year-old "Canterbury Tales" are for all but a few scholars today.
"No culture has ever tried, self-consciously and scientifically, to design a symbol that would last 10,000 years and still be intelligible," said David B. Givens, an anthropologist who helped plan the nuclear-site warnings. "And even if we succeed, would the message be believed?"
The Energy Department predicted such a problem when it began planning for the $9-billion waste dump, dubbed WIPP, in 1974 and for a similar repository in Nevada at Yucca Mountain, near Las Vegas. That site has not yet been opened. Eventually it will store highly radioactive spent fuel from nuclear power plants as well as high-level waste from the weapons program.
Trying to communicate across 500 generations posed an unprecedented challenge of linguistics, semiotics and materials science, so the government first asked scientists, futurists and historians to envision what the far-distant future might be like.
Their report combines dry analysis and projections worthy of sci-fi disaster films, including massive climate change and feminist corporations that disbelieve WIPP warnings because they were written by men. Civilization is so interdependent and fragile, one panelist grimly noted, "that any massive global catastrophe might lead to reversion to at least a preindustrial era." Greed or desperation could give rise to legends that WIPP holds buried treasure -- apparently confirmed by surface warnings to keep out.
In a sense, they're right. Oil and gas deposits lie thousands of feet below the plant. In 100 or 5,000 years, an energy-poor government, company or gasoline-addicted tribe in a ruined society, like those depicted in the film "The Road Warrior," could adopt a "drill first, ask questions later" policy -- piercing the repository and pulling death to the surface.
Others predicted the invention of self-guided robotic "mole miners" that would penetrate the site from the side or below. In a scenario set in the year 11991, robotic slaves are infected with a computer virus that compels them to override their safety programming as they compulsively drill and construct mine shafts.
Opportunities for WIPP to fail, the experts agreed, are limited only by the imagination.
The government formed a separate panel of scientists, linguists and artists to create a warning scheme to counter the pessimistic projections. That group immediately rejected digital or paper records -- only a solution cast in stone could hope to solve a problem for the ages.
If Egyptian pyramids have lasted more than 5,000 years, today's monuments should fare better -- if built from prosaic materials, such as ultra-hard concrete. Scavengers stripped the pyramids bare for their once-shimmering marble skins.
The trefoil symbol for radioactive material might seem a natural alternative to text, but experts doubt that it will be understood by future societies any better than today's English. Consider the swastika, first used on pottery by European tribes in 4000 BC. It was adopted by ancient Troy and later became a holy icon of Hinduism. When the Nazis claimed it, the symbol became widely reviled.