By Joseph King and Natalia Papitashvili
For many years NSSDC has provided space physics data by each of several pathways. Most data sets were only supported by a subset of the pathways, providing a challenge to NSSDC's users (and to NSSDC) to ensure that users would know of all relevant and available data sets for any given user need.
Primary pathways to spacecraft data have been:
via ftp at nssdc.gsfc.nasa.gov/spacecraft_data;
via SPyCAT to the data held on the NDADS optical disk jukebox;
via CDAWeb, OMNIWeb, and COHOWeb to data held in CDF;
via ATMOweb and Ftphelper to selected ftp-accessible ASCII data.
Note that the first two of these provide file level access while the latter two provide graphical browsing and subsetting by parameters within data records.
NSSDC is now migrating much data from NDADS through DIOnAS software to a UNIX environment with a Sun Enterprise 3000 server and attached 1 TB of RAID disk. With the NSSDC intent to make this environment the primary server for ftp-accessible data and services (whether DIOnAS-involved or not), this computer has been designated nssdcftp.
The directory nssdcftp.gsfc.nasa.gov/spacecraft_data will host an increasing amount of data moved from both NDADS and nssdc.gsfc.nasa.gov/spacecraft_data. All IMP 8 data from both sources have already been moved to nssdcftp. These data include five data sets from NDADS (including one with data from four IMP experiments) and four data sets from nssdc/spacecraft_data for a total of nine data sets from eight experiments. The data sets from these two sources are indistinguishible from an ftp-user perspective, except that the DIOnAS-involved data sets have subdirectories for the attribute files discussed elsewhere. Additional integrations of data sets by spacecraft (currently in transition: ISIS) from NDADS and from nssdc/spacecraft_data will be realized as the data migration efforts proceed over the coming months.
Because ATMOWeb and Ftphelper are alternate pathways to ASCII and gzipped ASCII data that were ftp-accessible from nssdc/spacecraft_data, and those data were being moved from nssdc to nssdcftp, it was necessary to move the ATMOWeb and Ftphelper software to a new machine (a Sun Enterprise 250 server named lewes) which is tightly linked (NFS-mounted) to nssdcftp. This has been done.
Further, because OMNIWeb software accesses either CDF-formatted data or ASCII data according to the user's run-time specification of time resolution of interest (CDF for hourly, ASCII for daily or 27-day averages) and because those ASCII files were moving to the nssdcftp machine, the OMNIWeb software and the CDF files were moved to lewes from the machine rumba which mainly hosts CDAWeb and SSCWeb data and software. (It should be noted here that the CDF-formatted data underlying CDAWeb are ftp-accessible from rumba.) Finally, because COHOWeb is managed similarly to OMNIWeb, the COHOWeb software and CDF-formatted data were moved to lewes from rumba.
Also moved to nssdcftp/spacecraft_data from nssdc/spacecraft_data were selected data from spacecraft other than IMP 8 which were both ftp-accessible and accessible through the ATMOWeb and/or ftphelper interfaces moved to lewes, namely: Atmospheric Explorer and Dynamics Explorer UA data plus data from the Hinotori, ARCAD-3, Prognoz, and Magsat spacecraft. Finally, nssdcftp also holds selected data from IMAGE, ISIS and a series of Russian spacecraft with particle data from Moscow State University. Again, much more will be added in the future.
CDAWeb and SSCWeb are unaffected by the changes reported above. The URLs for the OMNIWeb, COHOWeb, ATMOWeb and Ftphelper top Web pages remain unchanged (http://nssdc.gsfc.nasa.gov/...)