Cluster II scientists review new data system
29 June 1999Well over 200 scientists around the world are looking forward to receivingthe vast flow of data that will start streaming back next year from ESA'sfour Cluster II spacecraft. Apart from the ESA member states, they includeCo-Investigators from the United States, Russia, Czech Republic, Hungary,India, Israel and Japan.Since 44 instruments on the four Cluster II spacecraft will return about330 Gigabytes (330,000,000,000 bytes) of data over two years - equivalentto 165 million pages of printed text - the efficient worldwide distributionof this vast amount of information is of major concern to the sciencecommunity.
In preparation for this monumental task, members of the science team met in Stockholm last week to review current progress in the installation of the Cluster II Science Data System (CSDS), and to check the state of readiness of the computer software and hardware which will distribute the data.
"Everything seems to be coming together nicely and we are confident that the new data distribution system will be in place and ready to go by the time we launch next summer," said Project Scientist Philippe Escoubet.
Eight national data centres - six in Europe, one in the United States and one in China - will be used to receive, process and distribute data to the scientists. As a general rule, the national data centres are located near the scientific Principal Investigators who provide the software for processing data from their particular instrument.
Although small amounts of near real-time data will be available to the scientific Principal Investigators, the main method of distributing the raw data returned from the spacecraft will be through the regular despatch of CD-ROMs. These will be sent from the European Operations Centre (ESOC) in Darmstadt, Germany, to the national data centres.
Enough data to fill between one and three CD-ROMs will be returned to ESOC each day. The set of CD-ROMs for any one day must then be delivered within three weeks of first being acquired.
The Cluster II instruments will return information on many different physical characteristics of near-Earth space, ranging from electron density through electric and magnetic fields to particle distribution. Although each CD-ROM contains a full data set from all instruments, the individual centres only process part of it, so generating their own unique set of data products.
Using software provided by the relevant Principal Scientific Investigator, this data portion is processed and validated before being placed on the internet for the use of the national science community.
Each centre's processed data is also sent via the internet to the seven other national centres in the CSDS network. In this way, the full primary data set can be made available to the 222 Cluster II science Co-Investigators and any other interested scientists. Each centre is equipped with powerful Sun and Dec-Alpha computers and work stations which allow all scientists to access Cluster II data simultaneously.