NSSDC is aggressively exploiting the World Wide Web (WWW) in making its more popular data and services easily accessible to the research community as well as the general public. Through the NSSDC Home Page (http://nssdc.gsfc.nasa.gov/) and its subsidiary pages NSSDC provides access to a number of interactive data systems that provide enhanced access to scientific data, spacecraft ephemerides, geophysical models, and comprehensive directory-level information about data and to static documents and textual information further identified below.
Interactive systems providing access to heliospheric and magnetospheric data include OMNIWeb, COHOWeb, and CDAWeb. These interactive data systems, which are shown in the illustration below, provide capabilities of visualization, listing, subsetting, and data conversion through a WWW-based interface to the Interactive Data Language (IDL) and several generic data management applications. The dynamically generated data products (GIFs, PostScript files, subsetted Common Data Formats (CDFs), raw binary files, and ASCII files and listings) are displayed from an HTML page created from the Web server. Users make selections (e.g., time periods, data set, variables) from an on-line form and submit the selections to the NSSDC Web server; the requested data product is presented to the user. The generic framework is based on the CDF standard that provides machine-independent application and data where the data are self-describing. In addition to these systems, there are now generic WWW-based interfaces to the growing near-line data volumes of the NASA Data Archive and Distribution Service (NDADS) (the Space Physics Catalog [SPyCAT] mainly for space physics data and the Web Interface for Searching Archival Research Data [WISARD] mainly for astrophysics data).
Various WWW-based data systems offered by NSSDC.
Other interactive systems offer users the ability to specify their needs for ionospheric, atmospheric, or magnetospheric magnetic field model parameters in terms of time and place and to have those parameters computed on the fly and returned. Yet another key capability offered is the NASA Master Directory wherein the user may specify values for any subset of available selection parameters and have descriptions of and links to data sets satisfying the criteria returned.
Among the static items to which NSSDC's WWW pages provide access are software repositories (e.g., CDF toolkit, Coordinated Data Analysis Workshop [CDAW] data display software), documents (International Solar-Terrestrial Physics [ISTP]/Inter-Agency Consultative Group [IACG] Guidelines), newsletters (e.g., NSSDC News), journal articles (e.g., American Geophysical Union [AGU], Science Information Systems Interoperability Conference [SISIC], and WWW conference papers), Frequently Asked Questions (FAQs) (e.g., CD-ROM FAQ), and users' guides (e.g., CDF Users' Guide).
All of these services are accessible from the organization home page, which consists of a hierarchical menu structure to the various Disciplinary Services (Astrophysics, Space Physics, Solar Physics, Planetary Sciences, Earth Sciences and Life Sciences) and Multidisciplinary Services (NASA Master Directory, NSSDC On-Line Data and Information Service, and NSSDC Common Data Format). NSSDC has also indexed the entire Web server contents with a searchable WAIS interface that allows users to search for information that may be deeply nested within the many HTML documents. Searches range from a single keyword (e.g., Ulysses) to more complicated nested Boolean expressions such as "(volcano and image) or magellan not Viking."
NSSDC provides "What's New" pages from the NSSDC and discipline home pages as well as many other pages to help keep users informed as to what has been recently changed or added. As usual, contact information is provided at the bottom of nearly every page, but mechanisms have now been provided for feedback directly to the page developers in many cases. NSSDC is trying to serve the needs of its customers and evolve its services to meet these needs as well as use the latest technology.
Author:Miranda Beall (firstname.lastname@example.org)