A hard disk made of platinum-etched sapphire that lasts millions of years

Traditional Hard Disk Drives (HDD) last for a few years, but French researchers are working on some kind of completely different storage medium: a disk that’s made of sapphire and that will last for millions of years and hold information on the locations of nuclear waste sites.

Today, Patrick Charton of the French nuclear waste management agency ANDRA presented a sapphire disk, inside which information is engraved using platinum. The prototype shown costs €25,000 to make, but Charton says it will survive for a million years. The aim, Charton told the Euroscience Open Forum here, is to provide "information for future archaeologists." But, he concedes: "We have no idea what language to write it in."

The sapphire hard disk is one of the solutions ANDRA and other European organizations dealing with nuclear waste are trying to develop to answer a very difficult question: how to inform future generations about the proximity of a nuclear deposit and the right way to deal with the radioactive waste it contains?

The sapphire disk is made from two thin disks, about 20 centimeters across, of industrial sapphire. On one side, text or images are etched in platinum—Charton says a single disk can store 40,000 miniaturized pages—and then the two disks are molecularly fused together. All a future archaeologist would need to read them is a microscope. The disks have been immersed in acid to test their durability and to simulate ageing. Charton says they hope to demonstrate a lifetime of 10 million years.