A few days ago a new data library came into operation at the German Satellite Data Archive, D-SDA. The volume of earth observation data is increasing almost exponentially, requiring a 60 petabytes (60 billion megabytes) expansion of D-SDA storage capacity. D-SDA safeguards long-term the data from German and international earth observation missions and makes them available for research.
The Satellite Data Archive, D-SDA, is currently growing by 20-30 terabytes every day. Besides data from national missions like TerraSAR-X und TanDEM-X, the additional enormous volume of data flowing from the Sentinel satellites of Europe’s Copernicus programme is the main reason for this rapid growth. On behalf of the European Space Agency ESA, D-SDA has assumed responsibility for the long-term storage of the output from several Sentinel satellites. In order to safely preserve and make available these irreplaceable data for current and future users, every satellite image is stored in two physically separated libraries.
The almost exponential increase of earth observation data will continue also into the future. The new library now offers additional space for some 10,000 magnetic tapes, each with a storage capacity of 6 terabytes. The now-available 60 petabytes would be sufficient to safeguard about 120,000 years’ worth of music in MP3 format. For the back-up copies of data from Sentinel-1, -2, and -3 this space is expected to last only seven years. In addition to considerable hard disk space, D-SDA currently has a total of some 185 petabytes of storage space for primary and back-up copies. About two-thirds of this capacity is now at DLR in Oberpfaffenhofen, and one third at DLR in Neustrelitz.
The time series in the archives of D-SDA are an irreplaceable treasure for geoscientists as they carry out research on important contemporary issues like climate change and its effects. Many postulated trends and research results can only be identified and confidently verified statistically with data covering long periods of time. Elaborate safety concepts are required to safeguard this unique data resource for decades and thus make such analyses possible. Consequently, internationally recognized guidelines are being systematically implemented at D-SDA to safeguard earth observation data long-term. They were developed by an ESA-coordinated task force with important DLR contributions. For example, the guidelines specify on principle storage of two copies in separate buildings on data media from different producers. As part of the expansion of the archive, additional security was provided in these buildings through new structural, electronic, cooling and fire prevention measures.
In order to safeguard the data also from major disasters, the primary and back-up copies are not only to be stored in different buildings in the future, but also at different locations, in Oberpfaffenhofen and Neustrelitz. This could not be tackled previously because there was not yet enough network bandwidth. In addition to improved safety, this expansion would be a competitive advantage in the case of large international tenders.