In the second half of the 1980s, NSSDC made its most widely desired data network-accessible from its magnetic disks. However, the vast majority of its data remained off line owing to magnetic disk costs.
As the 1990s dawned, NSSDC undertook to make a much larger fraction of its archived data network-accessible and to provide network-accessibility to newly inflowing data. This accessibility was enabled by the NASA Data Archive and distribution Service (NDADS), a VAX-hosted pair of Cygnet jukeboxes capable of holding about 1.6 TB of data on 12-inch Sony\WORM platters.
Initial NDADS data management software and user interface software were built at NSSDC by a team led by Michael Van Steenberg. The initial interface, the Automated Retrieval Mail System (ARMS), was E-mail-based. Subsequent WWW-based interfaces, the Web Interface for Searching Archival Research Data (WISARD) for astrophysics data and the Space Physics Catalog (SPyCAT) for space physics data, were built later and now are the primary pathways to NDADS data.
NDADS became operational in late 1991 and provided access to much International Ultraviolet Explorer (IUE) data at that time. The diversity of data on NDADS has grown continuously since then. NDADS was and continues to be a very popular data access pathway for NSSDC's scientific user community.
In October of 1998, the two millionth data file was retrieved and downloaded by a member of that community. Owing to NASA constraints NSSDC was not able to offer that user a trip to Hawaii in recognition of that milestone. Over the years the most popular data sources on NDADS have been IUE and the InfraRed Astronomical Satellite (IRAS) in astrophysics and the Interplanetary Monitoring Platform (IMP) 8 and the International Solar-Terrestrial Physics (ISTP) in space physics.