CDPP archive

New developments for oldest CDPP archive data


ESA's GEOS missions (GEOS-1 and GEOS-2) aimed to study particles, fields and plasmas of the Earth's magnetosphere from a geostationary orbit. GEOS-1 was launched on April 20, 1977 by a Thor Delta vehicle from Cape Canaveral, and GEOS-2 was launched on July 14, 1978 under the same conditions.

Of the six experiments on board, only two to date have been saved, as well as, and fortunately, the auxiliary data, and in particular the positions.

These datasets were kept at the original laboratory, the CRPE, which later became CETP then LPP, and archived at CNES in the form of magnetic tapes, then as files in the original format of 60-bit CDC words ( the computers of the CNES at this time, on which the data was processed). These datasets were unusable because of their format, but they could sleep to be kept for more than 30 years in the CNES archives.

The documentation of the telemetry format having been preserved, it was possible to re-read these data 40 years later on modern computers .... Thanks to the financial support of CNES, a reading program could be developed, and all the data were thus re-read and could be reconverted recently in ASCII format, then in CDF, and archived at the CDPP. The processing of the STAFF-SC data from CLUSTER having made it possible to develop a program of continuous calibration of the waveforms, it was possible to make a version of it for the equivalent data of GEOS, and thus to obtain data waves calibrated in nT.

The wave data from experiment S300 (UBF, telemetry data and data calibrated in nT), from experiment S331 (Magnetometer, in nT), and position data ( km) are now available on the CDPP website in this uptodate formats.