Frosty Piss writes: No data storage medium seems to last long before becoming obsolete. This has become an issue for the builders of nuclear waste repositories, who are trying to preserve records of what they've buried and where, not for a few years but for tens of thousands of years. The solution may be a sapphire disk inside which information is engraved using platinum. The prototype costs around $30,493 to make, but Patrick Charton of the French nuclear waste management agency ANDRA says it will survive for a million years. The aim, Charton says, is to provide 'information for future archaeologists.' But, he concedes: 'We have no idea what language to write it in.'