A coin-sized glass disc holding the human genome now sits in an Austrian salt mine
In 2024 researchers laser-etched all three billion characters of the human genome onto a glass disc the size of a coin, added a picture key inspired by the Pioneer spacecraft plaques, and stored it in the Memory of Mankind archive inside the world's oldest salt mine, at Hallstatt in Austria.
The disc uses so-called 5D optical storage, nicknamed Superman memory crystal after the Kryptonian crystals of the comics. Ultrafast femtosecond laser pulses write tiny nanostructures throughout a block of fused quartz, a chemically stable glass. Nothing exotic is going on with extra dimensions: the five refer to each structure's size, its orientation and its three-dimensional position. Reading it back takes an optical microscope combined with a polarizer.
Ambitions are huge. At the largest 12-centimetre size, a disc could in principle hold up to 360 terabytes for billions of years. Writing data inside glass with such lasers was first proposed and shown in 1996. Swinburne University of Technology demonstrated the technique in 2009 and Kazuyuki Hirao's lab at Kyoto University in 2010, and Peter Kazansky's group at the University of Southampton proved the full concept in 2013. Early discs were tested for 3,100 hours at 100 degrees Celsius and still worked perfectly a decade later.
Headline projects followed. In 2016 Microsoft Research Cambridge teamed up with Southampton on Project Silica, aimed at long-term cloud archiving, and in 2019 it stored and recovered the 1978 film Superman on glass. Kazansky had already sent a copy of Isaac Asimov's Foundation trilogy into space in 2018 aboard Elon Musk's Tesla Roadster, working with the Arch Mission Foundation.
The technology is now sold by SPhotonix as 5D Memory Crystal, written with a process it calls FemtoEtch. In July 2025 it preserved its first video game, Heroes of Might and Magic III, in partnership with Good Old Games. Hitachi has explored related glass storage too.
Source: 5D optical data storage
