Started in Spring 1996, the ESA/PRODEX project for the archiving of the Ulysses/SWICS instrument data, involves the development of all software components needed for the setup and operation of the archive. Because the Ulysses mission is a joint ESA/NASA venture, the data archive will be located both at the European Space Research and Technology Center (ESTEC) in Noordwijk (NL) and at the National Space Science Data Center (NSSDC) near Washington (USA).
The following diagram gives an overview of the different steps required to establish the SWICS data archive and shows the different institutions involved:
The Level-0 or raw data are delivered once per month on CD-ROM directly from the NASA Jet Propulsion Laboratory (JPL) to the Physics Institute of the University of Bern. These data, approximately 60 MB per month, contain not only SWICS mass spectrometer data, but also Ulysses telemetry and housekeeping data, which are of no relevance for the archive. The first step in preparing the archive data therefore is to extract the relevant science data through the SWICS Archive Generator (SAGEN) application and to store them in Common Data Format (CDF) files. These CDF files do not only contain the instrument data but also the corresponding metadata, which are an essential part for long-term data archiving. These data files and the accompanying SWICS instrument calibration file make up the Level-1 data and are archived at ESTEC and NSSDC. Per month, approximately 15 MB of (uncompressed) Ulysses/SWICS data are archived. The data files on the archive DVD are stored in compressed CDF format and therefore require much less storage (approximately 15MB / year).
The advantage of archiving Level-1 instrument data is their calibration independence. Thereby whenever more accurate calibration data become available, there is no need to regenerate several thousand archived files, but only a single calibration data file needs to be updated.
Finally the SWICS Archive Processor (SAPRO) application is used to compute the actual science (Level-2) data from the archived CDF and calibration files. SAPRO has a simple Command-Line Interface, which allows the integration on a Web-Server at ESTEC/NSSDC, thereby making the Ulysses/SWICS archive on-line accessible.
The software documentation is divided into three parts:
The Archive Software User's Guide (HTML)(PDF) is intended for users only interested in using the SAPRO software for the extraction and calibration of the Ulysses/SWICS Archive data for scientific analysis and research projects.
The Archive Software Developer's Guide (HTML) is intended for users wishing to extend or integrate the accompanying software for their own purposes. This part of the documentation contains a detailed technical description of the CAPPA software framework used to implement the Ulysses/SWICS Archive applications.