Digital preservation and the digital archaeologist
We can read written materials from thousands of years ago. Their physical nature and careful preservation means they will be available to generations to come.
The rate at which digital technology is moving means that formats are created and either abandoned or superseded at an alarming rate. Without careful, and expensive digital preservation, we are in danger of entering a “digital dark age”. Digital preservation is required for analogue materials which have been digitised and materials that were created, or “born”, in digital format.
Our heritage has been presented on many different materials, including stone, vellum, bamboo, silk, paper etc. However, huge amounts of contemporary information exists in digital forms, including emails, blogs, social networking websites, web photo albums, and sites which change their content over time. Ironically, old media such as paper is far more persistent than CD or DVD. The former will last six decades before showing any signs of deterioration, whilst the life expectancy of optical discs (even if stored correctly) can be as little as twenty years. A greater problem comes when such materials only exist somewhere out there in the digital cloud.
The challenge comes in storing such materials in a way that allows us to easily find them again, and in a form which can still be read in the future. The former can be achieved by the use of meta tags. One system which has been suggested is METS ( Metadata Encoding and Transmission Standard). METS uses XML to describe the hierarchical structure of digital library objects, the names and locations of the files which constitute the objects and the associated metadata. We also have the Reference Model for an Open Archival Information System (OAIS) and the reference model (ISO 14721:2003).
The last significant threat is that of the obsolescence of the equipment required for the retrieval and playback of digital media. When a software or decoding technology is abandoned, or a hardware device is no longer in production, records created under the environment of such technologies are at great risk of loss, simply because they are not tangible any more. Those of us of a certain age will remember the pioneering Doomsday Project by the BBC in 1986. It created a digital version of the Doomsday Book (an 11th Century census of England), stored on laserdiscs in the LaserVision Read Only Memory (LV-ROM) format, read by a Philips VP415 “Domesday Player” and an Acorn BBC Master computer. The project represented the contributions of one million people. Even at the time the UK’s National Data Archive were informed that the technology used was short lived, but they failed to preserve the material effectively.
A famous example is with NASA, whose early space records were suffering from a “Digital Dark Age” challenge. For over a decade, magnetic tapes from the 1976 Viking landings on Mars were unprocessed. When later analyzed, the data were unreadable as they were in an unknown format and the original programmers had either died or left NASA. The images were eventually extracted through many months of puzzling through the data and examining how the recording machines functioned.
In essence, if you want media to still be there in a thousand years from now, you can not rely on electronics to achieve it for you.