Compact Disc Media Evaluation--What We Now Know about Disc Quality.

The research described in this article was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory, California Institute of Technology.—MM When NASA's Planetary Data System (PDS) adopted CD-ROM as the primary media for archival data products, it did so with the expectation that CD-ROM would be both standardized (i.e., readable on any platform, unlike other optical media) and permanent (i.e., capable of maintaining all data errorfree for several decades). At some point, the availability of hardware becomes questionable, but is assuaged by the proliferation of drives and the ability to `archive' a drive system cheaply I have a `fantasy-plan' to celebrate the completion of the first stage of planetary data restoration in 1995 by producing a time capsule. It would consist of a complete set of CDs (by then 500 to 1,000 discs), stored in ten hermeticallysealed coffee cans along with a solarpowered PC and CD-ROM drive. I would bet that such a time capsule could be opened up in 1,000 years and the discs played back error-free. This fantasy has been questioned recently. Articles in the Wall Street Journal and other periodicals have questioned the longevity of CD media. One explicitly predicted d five-year maximum life due to oxidation of the metal reflective layer on CD-ROM discs. Such assertions have spurred both CD-ROM manufacturers and users to provide proof of longevity expectations. These efforts include a media life study by 3M Corporation; the formation of a longevity evaluation group of SIGCAT (Federal Special Interest Group for CD-ROM Applications and Technology); and the development of a strict quality control specification for CD-ROM production by government and industry representatives. PDS and the Data Distribution Lab have actively participated in these efforts. PLAIN TALK: CD-ROM LIFETIME